Casting Forming Welding Pune University MCQs

 This set of Tough Casting Questions and Answers focuses on “Difference between Pattern and Casting”.

1. Which of the following statement is true?

a) Casting is the replica of the object to be cast

b) Pattern is the replica of the casting object

c) Casting and the pattern are same things

d) Molten material is casted into the casting cavity

Answer: b

Explanation: Pattern is the replica of the object. Except for the core prints and allowances, the pattern exactly resembles the casting.

2. Which of the following carries the mould cavity where the metal is to be poured?

a) Casting

b) Pattern

c) Sand

d) Core

Answer: b

Explanation: For casting to be made, the pattern is filled with the molten material and then it is allowed to be solidified, using proper cooling rates before it is extracted out.

3. Which of the following is ‘not’ an allowance given to the pattern for casting?

a) Shrinkage

b) Draft

c) Hole

d) Machining

Answer: c

Explanation: A hole is made during the machining or finishing of the casting and is not a type of allowance given to the pattern.

4. The following diagram shows the application of which of the allowances given to a pattern?

tough-casting-questions-answers-q4

a) Shrinkage allowance

b) Draft allowance

c) Shake allowance

d) Distortion allowance

Answer: b

Explanation: Draft allowance is given so as to ease the removal of casting from the pattern without damaging the pattern. Hence, tapering the vertical faces with some draft allowance is provided which is machined later.

5. What will be the machining allowance for a bore of a 405mm cast iron object to be casted?

a) 1.0mm

b) 2.0mm

c) 3.0mm

d) 5.0mm

Answer: d

Explanation: The machining allowance for cast iron of various dimensions is shown in the table below.

DIMENSIONS ALLOWANCE

BORE SURFACE COPE SIDE

upto 300 3.0 3.0 5.5

301-500 5.0 4.0 6.0

501-900 6.0 5.0 6.0

6. The quality of the final product is not dependent on _______________

a) Method of withdrawal of pattern

b) Allowance provided to the pattern

c) The complexity of the casting

d) The metal used in Casting

Answer: d

Explanation: Metal used in casting is a concern till its viscosity affect the flow or occupation to the cavity. This does not affect the final product physically, once the metal has solidified.

7. The life of a pattern is most likely to depend upon which of the following term?

a) Number of castings produced

b) Type of cooling rate of the casting

c) Size of the casting

d) Size of the pattern

Answer: a

Explanation: Obviously, the more casting produced means more exposure of the pattern to the elevated temperature of molten metals and hence, slowly causing distortion to the sand grains as well as the pattern material.

8. What is the function of cores in the casting process?

a) To support the pattern

b) To provide differential cooling rates at specific portions

c) To make holes and cavities

d) For ease of flow of the molten material

Answer: c

Explanation: Cores are the elements used to provide hollow cavities and holes in the pattern which are difficult or non profitable to be given after the casting is done by machining.

9. Which of the following is ‘not’ an advantage of the usage of pattern in a casting of metals?

a) Using patterns to cast objects, less time is consumed for mass production

b) It is cost efficient and profitable for mass production

c) Production of the pattern requires extra effort to cast the object

d) Cores in the pattern could be used to decrease the amount of machining done for making cavities

Answer: c

Explanation: Production of patterns requires additional efforts but is justified for mass production only, where more products are formed in less time and overcomes the effort and cost of making patterns.

10. A draft allowance is provided to ___________

a) All linear faces

b) Only the interior dimensions

c) Only the exterior dimensions

d) Only the dimensions that are perpendicular to the parting plane

Answer: d

Explanation: The draft allowance is used for those dimensions which are perpendicular to the parting plane, to give out a tapered face which is machined later.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Functions of a Pattern”.

1. Which of the following is not a part of the pattern at most times?

a) Mould cavity

b) Cope

c) Molten metal

d) Core

Answer: c

Explanation: Molten material is poured into the mould cavity to make a casting, after solidification and hence, it does not constitute the pattern.

2. Which of the following does not serve the purpose of using patterns in sand casting?

a) Contain core prints if the casting requires a core and need to be made hollow

b) To give the exact shape and size  to the casting as that of the final object

c) Reduces the cost of production while used in mass production

d) Sometimes used to carry the mechanism to melt the metal/material which is to be poured into the cavity

Answer: d

Explanation: The pattern never carries or includes the mechanism to melt the metal, which needs to be poured into the cavity. This job needs to be done externally.

3. Name the missing part of the pattern in the diagram labelled as ?

casting-questions-answers-functions-pattern-q3

a) Core

b) Riser

c) Sprue

d) Mould cavity

Answer: a

Explanation: The illustrated part in the diagram is core. The core in a pattern is used to create holes or hollow cavities.

4. The function of a gated pattern is ___________

a) To produce small castings in mass production

b) To create castings of a very heavy mass

c) To create castings containing complex design

d) To create symmetrical castings

Answer: a

Explanation: Gated pattern manufactures huge no. of products using single time casting using a common gating inlet system. Hence, the casting needs to be small and simple and is only justified for mass production, as the pattern is used for 1-2 times only.

5. Which of the following factors affect the choice of a pattern at most times?

a) Size and complexity of the casting

b) Characteristics of castings

c) Type of molding and castings method to be used

d) Type of cooling rates to be provided

Answer: d

Explanation: The type of cooling rates depends upon the required strength in the casting, which cannot be controlled by the type of any pattern. Proper chills are to be used for that purpose.

6. Which of the following sequence is in the correct order to prepare a cast using the sand casting method?

[1] Mould making [2] Clamping [3] Pouring [4] Cooling [5] Trimming [6] Removal

a) 1,3,2,4,6,5

b) 2,1,3,4,5,6

c) 1,2,3,4,5,6

d) 1,2,3,4,6,5

Answer: d

Explanation: For a proper casting to be carried out, the correct order in which processes are to be executed out starts with mould making then clamping it then pouring the metal then cooling then removing it and at last trimming it or providing machining.

7. What is a function of a riser in a sand casting?

a) Provide good mobility to the molten metal

b) Prevent cavities due to shrinkage

c) To develop holes or hollow cavities in the casting

d) To provide differential cooling rates in specific areas of the casting

Answer: b

Explanation: The risers also known as feeders are used to decrease the phenomena of shrinkage during solidification of the molten metal.

8. Runners, gates and risers are attached to the pattern to __________

a) Provide ease of cooling

b) Provide feed to the molten material

c) Provide design to the casting

d) Enhance the finishing of the casting

Answer: b

Explanation: These external elements are added to the pattern or mould cavity to enhance the flow of molten metal, hence, to enhance the casting process.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Pattern Materials”.

1. Pattern cannot be constructed out of which of the following materials?

a) Wood

b) Wax

c) Oil

d) Metal

Answer: c

Explanation: Oil is used as fuels for melting metals in various furnaces. It cannot be used for constructing a pattern, while all other materials are used for making patterns.

2. Which of the following is not a criteria for selecting pattern materials?

a) Method of moulding

b) Establishment of parting line

c) Chances of repeat orders

d) Complexity of the casting

Answer: b

Explanation: While selecting a pattern, pattern establishing a part line is counted under functions of the pattern, and not under the criteria for selecting it. Whereas all the other remaining are factors used for choosing the right pattern materials.

3. Which among the following wood is most widely used for making patterns?

a) White Pine

b) Mahogany

c) Teak

d) Maple

Answer: a

Explanation: White Pine is used most widely for making patterns because, white pine wood is soft and it is also observed that, it is comparatively easy to work on this wood. Also, this wood is comparatively cheap.

4. Which of the following is considered to be light wood?

a) Mahogany

b) Maple

c) Birch

d) White Pine

Answer: d

Explanation: Among these four woods, White Pine is considered to be the lightest wood. White Pine is used most widely for making patterns because, white pine wood is soft and it is also observed that, it is comparatively easy to work on this wood.

5. Steel is an alloy of which two elements?

a) Iron and Brass

b) Brass and aluminium

c) Iron and carbon

d) Carbon and aluminium

Answer: c

Explanation: Steel is an alloy of carbon and iron. Carbon is present in the alloy up to 2% by weight and it takes up interstitial sites of the microstructure of iron. There are three types of alloys classified in this, high alloy steel, low alloy steel and medium alloy steel.

6. Which of the following is not a limitation of wooden patterns?

a) Get abraded easily

b) Absorb moisture

c) Difficult machining

d) Poor wear resistance

Answer: c

Explanation: Wooden patterns are the easiest to get machined than all the other materials which are used for making patterns, and hence is counted as one of its advantage and not limitation.

7. Metal patterns have a longer life than wooden pattern.

a) True

b) False

Answer: a

Explanation: It is true that, metal patterns have a longer life than wooden patterns, as metal patterns are stronger and accurate as compared to wooden patterns.

8. Which of the following is not a limitation of metal patterns?

a) Get rusted

b) Obtain rough surface finish

c) Expensive

d) Heavy

Answer: b

Explanation: In metal patterns, it is extremely easy to obtain a smooth surface finish. To achieve a smooth surface finish, it is counted as an advantage in metal patterns over wooden patterns.

9. Which of the following patterns do not withstand rough handling?

a) Aluminium

b) Cast iron

c) Brass

d) Steel

Answer: a

Explanation: It is one of the limitation of aluminium pattern that, it cannot withstand rough handling, while all other metal and alloy patterns can withstand it. Aluminium is the lightest metal known.

10. Which of the following has the lowest melting point?

a) Cast Iron

b) Steel

c) White Metal

d) Brass

Answer: c

Explanation: Among the given metals and metal alloys, white metal  has the lowest melting point which is approximately 260 degrees Celsius.

11. Which of the following is the heaviest?

a) White

b) Brass

c) Cast Iron

d) Aluminium

Answer: b

Explanation: Aluminium and White metal are considered to be one of the lightest metals and alloys, whereas brass and cast irons are considered to be heavy materials. But, even among the two, brass is heavier than cast iron.

12. In Solid casting method, the resin mixture is kept for how much time for hardening and curing?

a) 1-2 hours

b) 2-3 hours

c) 3-4 hours

d) 4-5 hours

Answer: b

Explanation: A mould of Plaster of Paris is made, into which the resin mixture is poured, in solid casting. This mixture takes up 2-3 hours to harden and get cured.

13. Core boxes are made out of which pattern?

a) Plaster pattern

b) Wax pattern

c) Metal patterns

d) Polystyrene patterns

Answer: a

Explanation: A pattern is basically a duplicate of the object that has to be casted. It is one of the applications of plaster pattern to make core boxes and other small and intricate patterns.

14. What should the sulphur level in foam plastic be?

a) More than 1%

b) Between 0.5% to 1%

c) Less than 0.1%

d) Between 0.1% to 0.5%

Answer: c

Explanation: In foam plastic, for making pattern, the sulphur level must be below 0.1%. If the levels are higher than mentioned, it can be deleterious in manufacturing.

15. Which of the following patterns has high compressive strength?

a) Plastic pattern

b) Wax pattern

c) Polystyrene pattern

d) Plaster pattern

Answer: d

Explanation: Among plastic patterns, wax patterns and polystyrene pattern, it is plaster pattern which has the highest compressive strength. The calculated compressive strength is as high as up to 285kg/cm 2 .

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Types of Pattern”.

1. Which of the following factor is not considered while selecting a kind of pattern?

a) Quantity of casting

b) Types of moulding method

c) Shape of the casting

d) Nature of moulding process

Answer: d

Explanation: Nature of moulding process is a factor used selecting pattern materials, whereas the quantity of casting, types of moulding method and shape of the casting are used for selecting a type of pattern.

2. Which type of pattern should be used for making stuffing box of the steam engine?

a) One piece pattern

b) Split Pattern

c) Sweep pattern

d) Gated pattern

Answer: a

Explanation: One piece pattern operations for moulding are used for manufacturing a small number of casting only. Hence, a stuffing box can be casted with this type of pattern.

3. The following figure represents which type of pattern?

casting-questions-answers-types-pattern-q3

a) One piece pattern

b) Split Pattern

c) Sweep pattern

d) Gated pattern

Answer: a

Explanation: The given figure here is depicting a one piece pattern. Here, as we see, there are no loose pieces available or any joints that bring it together. As there are no components or loose pieces attached to it, it is a one piece pattern.

4. The following figure represents which pattern?

casting-questions-answers-types-pattern-q4

a) Follow board pattern

b) Gated pattern

c) Match plate pattern

d) Segmental pattern

Answer: d

Explanation: The following figure we see there is a pivot. This pivot rotates in two directions namely, clockwise and anti-clockwise directions. A pattern with such an apparatus is called as Segmental pattern.

5. In a three piece pattern moulding arrangement, what keeps the alignment between the two parts of the pattern?

a) Cope

b) Drag

c) Dowel pins

d) Cheek

Answer: c

Explanation: Cope and drag are the portions of upper and lower part of the split and cheek form the middle one. Dowel pins are used for the alignment work in the pattern.

6. Piston rings are produced using which pattern?

a) Sweep pattern

b) Gated pattern

c) Match plate pattern

d) Loose piece pattern

Answer: c

Explanation: Match plate pattern are usually used for manufacturing small castings on a big scale. Hence, piston rings of the engine are made using this pattern.

7. Match Plate pattern consumes more time in moulding operations than loose piece pattern.

a) True

b) False

Answer: b

Explanation: In loose piece pattern, the pattern is drawn out first and then the loose pieces, which consumes more time. On the other hand, match plate casting is used for small casting only, hence operates in less time.

8. Which of the following pattern operation is cheapest?

a) Sweep pattern

b) Gated pattern

c) Match plate pattern

d) Skeleton pattern

Answer: d

Explanation: Skeleton pattern uses the least amount of material for the operations on pattern and therefore, it does not need a lot of investment on its materials, making it inexpensive.

9. Which pattern operation is used for manufacturing wheel rims?

a) Follow board pattern

b) Segmental pattern

c) Sweep pattern

d) Gated pattern

Answer: b

Explanation: In segmental pattern, it does not revolve continuously to make the mould, but completes one part of the mould and then goes to make the next portion. Hence, such type of pattern is used for making wheel rims and big gears.

10. The skeleton pattern is filled with sand.

a) True

b) False

Answer: a

Explanation: In skeleton pattern, the skeleton is made up of wood and then sand is added to the pattern. After putting the sand, then the pattern is rammed.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Pattern Design”.

1. The designing of a pattern does not include which of the following feature?

a) To locate the direction of the parting line and adjust the component accordingly

b) To determine regions and measurement of draft angles and radii of the sharp edges where allowances are to be given

c) To recognize and abolish the region of or where the defects could take place during casting

d) To 3D print the design for making the pattern

Answer: d

Explanation: The printing of a design is executional operation of that casting design. The design is meant for study the casting structure and modify it accordingly if needed.

2. Calculate the size of cylindrical riser  to feed a steel slab casting 25x25x5 cm.

casting-questions-answers-pattern-design-q2

a) 10cm

b) 12.5cm

c) 14cm

d) Data insufficient

Answer: b

Explanation: a = 25cm b = 5cm c = 25cm

Modulus Mc = /2 = Mc = /2 = 125/60 = 2.0833cm

The riser diameter D = 6 x Mc = 6×2.0833 = 12.5cm.

3. Calculate the riser diameter for an annular cylinder of 30 cm outer diameter, 10 cm inner diameter and 30cm height. 

a) 22cm

b) 20cm

c) 22.6cm

d) 20.6cm

Answer: c

Explanation: Core dia = 10cm Plate thickness = 10cm Correction factor = 1.14

casting-questions-answers-pattern-design-q3

Riser Volume = 0.48 x 18849 = 907.52 cm 3

∴ Riser diameter = 22.585cm = 22.6cm.

4. The relation between modulus of riser and modulus extension factor is __________

a) casting-questions-answers-pattern-design-q4a

b) casting-questions-answers-pattern-design-q4b

c) casting-questions-answers-pattern-design-q4c

d) casting-questions-answers-pattern-design-q4d

Answer: a

Explanation: Mr` = 1.2 ⁄ f Mc represents the correct relation between modulus of riser and modulus extension factor  where Mc is the modulus, f is the introduction factor or MEF and Mr` is the reduction in modulus. The MEF is required where the riser is required for longer times.

5. The preferred shape of a runner in a sand casting is ___________

a) Cylindrical

b) Spherical

c) Rectangular

d) Trapezoidal

Answer: d

Explanation: Trapezoidal runner is most preferable in sound sand casting as it provides good flow with less distortion or splattering of molten metal.

6. Find out the error in the following design of a casting.

casting-questions-answers-pattern-design-q6

a) The vertical faces must be tapered  only

b) The cavity must be created using some additional elements  only

c) The vertical faces must be tapered as well as the cavity must be created using loose piece

d) Nothing needs to be done 

Answer: c

Explanation: Draft allowances well as loose piece needs to be provided to the pattern in order to maintain the quality of the casting. The corrected design is drawn below: casting-questions-answers-pattern-design-q6a

7. Riser for a sand casting can be designed using ___________

a) Modulus method

b) Cained method

c) Naval research laboratory method

d) All of the mentioned

Answer: d

Explanation: The three of these methods- modulus, Cained and NRLM are used to calculate and design Riser for a sand casting.

8. Rat tails and buckles in sand casting are caused by __________

a) Lower strength of the solidified metal

b) Lower refractoriness of the moulding sand

c) Lower strength of the moulding sand

d) Lower hardness of the moulding sand

Answer: c

Explanation: Lower strength of the moulding sand causes rat tails and buckles type of defect in manufacturing of casting.

9. Which of the following diagram is best suitable for least stress generation at the bent?

a) casting-questions-answers-pattern-design-q9a

b) casting-questions-answers-pattern-design-q9b

c) casting-questions-answers-pattern-design-q9c

d) casting-questions-answers-pattern-design-q9d

Answer: c

Explanation: The diagram which has round filets around the inner as well as the outer corners, the tress generation will be least as compared to the other diagrams.

10. Parting line in the sand casting should be ___________

a) Simple and curved

b) Simple and straight

c) Irregular

d) Any type will not make a difference

Answer: b

Explanation: The parting line needs to be simple and straight to create a difference between upper part and lower part.

This set of Casting Interview Questions and Answers focuses on “Pattern Making”.

1. Which of the following is not measuring, marking or layout tools?

a) Caliper

b) Trisquare

c) T-bevel

d) Compass Saw

Answer: d

Explanation: A caliper, a trisquare and a T-bevel are few of the tools used for measuring, marking and layout tools used by a pattern maker for making pattern. A compass saw is not a part of it.

2. Which of the following tool is not used for clamping purpose?

a) C-clamp

b) Trammels

c) Bar clamp

d) Hand Vice

Answer: b

Explanation: A trammel is a measuring, marking and layout tool. While C-clamp, bar clamp, and hand vice are tools which are used for clamping process.

3. Which of the following is not a sawing tool?

a) Coping saw

b) Pinch dog

c) Panel saw

d) Bow saw

Answer: b

Explanation: Pinch dog is one of the tools used for clamping processes. While coping saw, panel saw and bow saw are the different types of sawing tools.

4. Gimlet is which of the following tool?

a) Clamping tools

b) Drilling tool

c) Sawing tool

d) Wood planing tool

Answer: b

Explanation: Gimlet is one of the drilling and boring tools. Gimlet is used for making patterns but is not counted under clamping, sawing or wood planing tool.

5. Which of the following is not a drilling or boring tool?

a) Brace

b) Counter sink bit

c) Auger bit

d) Hand vice

Answer: d

Explanation: Hand vice is one of the tools used for clamping processes. While, brace, counter sink bit and ager bit are counted among drilling tools or boring tools.

6. Which of the following is not a wood planing tool?

a) Block plane

b) Scrub plane

c) Spokeshave

d) Centre bit

Answer: d

Explanation: Centre bit is counted among drilling and boring tool, whereas, bock plane, scrub plane and spokeshave are different types of wood planing tools.

7. A mallet comes under which type of tool?

a) Drilling tool

b) Clamping tool

c) Other pattern maker’s tool

d) Sawing tool

Answer: c

Explanation: A mallet comes under other pattern maker’s tool, as this tool cannot be used for drilling, clamping or sawing or any other classified purpose.

8. Which of the following pattern making machine works on two pulleys?

a) Circular saw

b) Band saw

c) Wood turning lathe

d) Jig saw

Answer: b

Explanation: A band saw utilises an endless metal saw band which has movement of two pulleys located one above the other in a vertical plane.

9. Which of the following pattern making machine makes wooden board?

a) Jointer

b) Drill press

c) Mortiser

d) Scroll saw

Answer: a

Explanation: A jointer or hand planer has its use in producing wooden boards and planks. Basically, a plane of uniform thickness.

10. Disc Sander is an abrasive type of machine.

a) True

b) False

Answer: a

Explanation: Abrasive type of machines has three types, belt sander, spindle sander and disc sander. Hence, disc sander is a type of abrasive type of machine.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Pattern Fillets”.

1. In pattern making, the term used for rounding out of external edges of the pattern is called as a fillet.

a) True

b) False

Answer: b

Explanation: The term used for rounding-out of external edges of the pattern is basically known as radii, and the rounding-out of internal corners of the pattern is known as the fillets on the pattern. Fillets are mainly provided to make uniform heating and cooling of the casting material and also for the less stress concentration.

2. Draft is generally provided to make a clearance between the pattern and the mould during pattern extraction.

a) True

b) False

Answer: a

Explanation: Draft angles are normally included into the pattern design to make easy extraction of a pattern from the mould cavity. Draft angles are used in most of the pro¬cesses in which a pattern is withdrawn from the mould prior to pouring. Draft is very necessary to provide a clearance between the pattern and the mould during pattern extraction.

3. It is not necessary to avoid any sharp internal corners from casting design, as it causes very negligible problems.

a) True

b) False

Answer: b

Explanation: Sharp internal corners on a casting design must be avoided whenever pos¬sible. The small volume of melt located in a casting’s internal corner quickly becomes superheated and transfer of heat becomes very difficult at this location, this further results in the formation of defects in the casting.

4. Lack of filleting of sharp corners in the casting design can cause hot spots in the casting.

a) True

b) False

Answer: a

Explanation: When filleting of sharp corners is not done properly, then it causes an interruption in cooling of casting that basically creates localized areas that solidify very slowly than the rest of the part, this result into the formation of hot spots in the casting, which causes various defects in the casting.

5. Sharp corners in casting design may cause defects in the casting but it helps in strengthening of pattern material.

a) True

b) False

Answer: b

Explanation: Sharp corners in casting design produce various defects in the castings and instead of strengthening, it makes the breaking of pattern material. Proper filleting reduces hot spots in the casting and eliminates defect from the casting. Fillets aid in the removal of the pattern from the mould and also strengthen the pattern.

6. Sharp corners in the casting design also produce the problem of sand inclusion in the castings.

a) True

b) False

Answer: a

Explanation: Sharp corners in the casting design causes hot spots which produce many casting defects, such as hot tears, metal penetration, shrinkage, cracking and gas-related defects. And the sharp edges on the metal are also prone to breaking off and may cause sand inclu¬sions in the casting.

7. In horizontally parted moulds, a draft is required for vertical as well as for horizontal surfaces of a pattern.

a) True

b) False

Answer: b

Explanation: The draft angle required on the pat¬tern mainly depends on the moulding process and the depth of pattern in the mould. Especially in horizontally parted moulds, only the vertical surfaces require a draft. Horizontal surfaces separate the pattern from the mould automatically during pattern removal.

8. In casting design, concave junctions are generally added to avoid the effect of sharp corners in the casting.

a) True

b) False

Answer: a

Explanation: To avoid the problem of sharp corners, usually concave junction or fillet is added, where the two casting surfaces meet. This fillet mixes the two intersecting surfaces and modifies internal corner into a rounded corner. This ef¬fectively avoids the small volume of sand in the corner that reduces hot spots in the casting.

9. In pattern fillets, the size of a fillet is usually determined by its width.

a) True

b) False

Answer: b

Explanation: In pattern fillets, the size of a fillet is generally determined by its radius, it is not measured by its width. Fillet sizes may vary, but it can be possible for a fillet to be too large. Proper filleting in the pattern makes the casting strong and more reliable that reduces the further cost of machining.

10. A very large fillet in casting design also may cause shrinkage defects in the casting.

a) True

b) False

Answer: a

Explanation: In pattern fillets, a large fillet adds extra metal to the junction, which also may cause shrinkage problems due to the variations in the volume of casting. So the best design is to main¬tain uniform section thickness whenever possible in the casting design to keep the casting stable and strong.

11. Sharp internal corner of the casting also causes the misrun defect in the casting.

a) True

b) False

Answer: b

Explanation: Sharp external corners can also produce casting defects. A misrun defect is basically caused by sharp external corners of the casting. External corners abruptly lose heat to the surrounding mould material and as a result, the corner might not fill completely that result into a misrun defect.

12. To avoid sharp external corners in casting design, rounding of external edges is done in pattern making that termed as radii.

a) True

b) False

Answer: a

Explanation: A radius is provided that termed as radii for rounding of external edges of a pattern to aid in removing the pattern from the mould and eliminating the sharp external edges from the casting. It also makes the casting more aesthetically pleasing than casting with sharper corners.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Finishing Patterns & Storing of Patterns”.

1. Finishing allowance to a pattern is generally provided to avoid various defects in the casting.

a) True

b) False

Answer: b

Explanation: Finishing allowance is generally provided for a machining process, the finish and accuracy achieved in sand casting are usually poor and therefore when the casting is functionally required to be of better surface finish, so the machining is required that is accomplished by providing finishing or machining allowance.

2. Finishing also includes removal of scales from the surface of the casting.

a) True

b) False

Answer: a

Explanation: When the casting is made in the mould cavity, some of the oxides layers called as scales adhere tightly to the surface of metal casting, which should be removed for making casting strong and durable. So to achieve this, proper finishing and cleaning are done with the help of tools to make casting free from scales.

3. Subsequent machining for products finishing does not require extra material to the metal casting, as it removes negligible amount of material from the casting.

a) True

b) False

Answer: b

Explanation: It is very necessary to include extra material to the metal casting to compensate it for subsequent machining which removes very fine particles to vanish roughness and to make casting smooth and aesthetically pleasant. Then the casting becomes ready for industrial application.

4. Which of the following ranges show the approx range of finishing depth  required for finished casting?

a) 2 to 20

b) 20 to 30

c) 30 to 35

d) 35 to 40

Answer: a

Explanation: The range of finishing depth basically depends on dimensions, the type of casting material and the surface finish required, but for the approximation, it comes in the range of 2 to 20 mm. In this range, casting can achieve greater surface smoothness and shiny surface with good appearance.

5. For finishing allowance, great care is taken while adding extra material to the molten metal.

a) True

b) False

Answer: a

Explanation: After extraction of casting from the mould cavity, the finishing allowance provided would ultimately have to be removed by machining. Hence, great care is taken while adding extra material as to maintain the cost of material. So it is always examined before finalizing for the production of casting.

6. Which of the following parts is used to keep the casting in for reducing the finishing allowance?

a) Centrifuge

b) Burette

c) Drag flask

d) Conical flask

Answer: c

Explanation: In finishing allowance, the entire casting is put in the drag flask to reduce the finishing allowance such that the dimensional variation and other defects due to the parting plane are reduced to a minimum. This part is widely used in the casting process to make the casting economical and sustainable.

7. Which of the following technologies is used in metal casting for reducing the product development time?

a) Radiography

b) UV radiation

c) Eddy current coiling

d) Rapid prototyping

Answer: d

Explanation: Rapid prototyping is used for decreasing the product development time in metal casting, in which parallel horizontal layers of material are formed with the help of equidistant layers in a computer through CAD software. This all is achieved by rapid prototyping without application of any finished pattern.

8. After providing the finishing allowance to the metal casting, it is not necessary to include shake allowance as it can be covered by finishing allowance.

a) True

b) False

Answer: b

Explanation: The purpose of shake allowance is totally different and opposite from finishing allowance. Shake allowance includes reducing of pattern dimensions, before implementing this, the casting made is generally large that is caused by the pattern removal which enlarges the mould cavity. So, shake allowance is provided, it is also called a negative allowance.

9. A Fillet is provided in the finishing of a pattern which is very small for shallow castings.

a) True

b) False

Answer: a

Explanation: Intersecting surfaces forming junctions of metal thickness are usually joined with fillets in order to avoid high stress concentrations in the metal casting. Shallow castings commonly have much smaller fillets, while the deep pockets and other interior complex corners may have larger fillets.

10. In finishing of a pattern, fillets are provided to eliminate the stresses completely from the metal casting.

a) True

b) False

Answer: b

Explanation: Stresses cannot be eliminated completely, only it can be reduced or distributed to the more part of the material. Fillet Radius makes the casting stronger because it redirects stresses from being concentrated at a sharp internal corner and distributes them over the broader volume of the fillet material.

11. Why is it important to take careful measurements/steps while storing the pattern?

a) They loose their shape and size

b) They get rusted

c) They get warped

d) All of the mentioned

Answer: d

Explanation: On long storage, if careful measurements are not taken then pattern materials tends to alter their dimension and the physical condition gets worse.

12. Temperature and humidity should be _________

a) Very low

b) Very high

c) Be controlled accordingly

d) Is not a matter of concern

Answer: c

Explanation: Neither too high nor too low temp is required but it is a factor to be controlled as to avoid pattern rusting or warping.

13. Time to time cleaning of stored pattern should be done by ___________

a) Distilled water

b) Dry cleaning

c) Treated with proper chemical fluids

d) Vegetable oils

Answer: b

Explanation: No dust or chemical or moisture should be left over the surface of the pattern for longer periods hence time to time dry cleaning is a must.

14. To ease the storing and assembly which of the following method is used by industries?

a) Colour pattern

b) Scanned copy/Photo

c) Coding and numbered

d) No measurements are taken

Answer: c

Explanation: Coding with numbers are the easier ways to distinguish the assemblies of patterns and ease its storing.

15. Which of the following method is obsolete for storing fragile patterns?

a) They must be stored in kerosene

b) They must be stored in wax plated shelves

c) They must be stored in a wood wardrobe

d) They must be stored in foam

Answer: d

Explanation: Foam has the ability to absorb shocks and sudden impacts to a very higher extent. Hence, Fragile patterns are stored while wrapped in foam.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Pattern Colour”.

1. While imparting colours to the patterns, which colour scheme is followed?

a) Indian

b) American

c) Australian

d) Britain

Answer: b

Explanation: Colours are imparted to the patterns for recognising different parts and has many other advantages. During impartation certain colours and shades to the pattern, it is the American colour scheme that is followed.

2. Which of the following reason is not valid for pattern colouring?

a) Identification of main body

b) Visualising the to be machined surface

c) Indication of the type of metal

d) Locating parting surface

Answer: d

Explanation: Locating pattern surface is one of the steps of pattern construction, whereas the identification of the main body, visualising the, to be machined surface and indication of the type of metal are the reasons as to why a pattern is imparted colour.

3. Green colour is used for machined cast surface.

a) True

b) False

Answer: b

Explanation: Green colour is not given to any of the casting surfaces. Cast surfaces which are yet to be machined are imparted with red colour. Green colour, as a matter of fact, is not provided to any pattern.

4. Which colour is given to the cast surfaces which are to be left not-machined?

a) Red

b) Blue

c) Black

d) Yellow

Answer: c

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, black colour is to be given for cast surface left to be not-machined.

5. Which colour is given to loose pieces and seatings?

a) Red strip on yellow base

b) Yellow strip on red base

c) Black strip on yellow base

d) Yellow strip on black base

Answer: a

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, red strip on yellow base is to be given for loose pieces and seatings.

6. Which colour is given to core prints seats?

a) Red

b) Blue

c) Yellow

d) Black

Answer: c

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, yellow colour is to be given for core print seats.

7. Which colour is given to stop-offs or supports?

a) Yellow strip on black background

b) Red strip on yellow background

c) Black strip on yellow background

d) Yellow strip on red background

Answer: c

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, black strip on a yellow background is to be given for Stop-offs or the supports.

8. Which colour is given to parting surfaces?

a) Red

b) Black

c) Yellow

d) No colour

Answer: d

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, no colour is to be given for parting surfaces, that is, it has to be kept clear.

9. Which colour is provided on core prints for machined openings?

a) Black strips on yellow background

b) Yellow strips on black background

c) Red strips on yellow background

d) Yellow strips on black background

Answer: b

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, yellow strips on the black background is to be given for machined openings of core prints.

10. Which colour is given for surfaces, yet to be machined in cast surface?

a) Red

b) Black

c) Yellow

d) No colour

Answer: a

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, red colour is to be given for casting surfaces yet to be machined.

11. Pattern surfaces have black colour.

a) True

b) False

Answer: b

Explanation: Provision of colour scheme makes it easy for one to detect the part and the operation to be performed on it. According to the American pattern colour scheme, pattern surfaces do not have any colour at all.

This set of Casting Questions and Answers for Entrance exams focuses on “Jointing Materials”.

1. To join pieces of timber in width and thickness is called?

a) Pattern filling

b) Mortising

c) Building-up

d) Brazing

Answer: c

Explanation: The process of joining pieces of timber in width and thickness is called as building-up. A mortise is a wood working machine, used for mortising tenon joints and brazing is used in welding.

2. Building-up process is used for making what?

a) Shields and boards

b) Dowels

c) Round pins

d) Belts

Answer: a

Explanation: None.

3. Which method is used for locking planks and bars?

a) Mortising

b) Building-up

c) Soldering

d) Brazing

Answer: a

Explanation: The process of locking planks and bars together at a given angle is called as mortising. A mortise is a wood working machine, used for mortising tenon joints. A mortise can also be used for cutting square holes in wood.

4. Wooden workpieces of a pattern set come in which of the following type?

a) Triangular

b) Circular

c) Hexagonal

d) Pentagonal

Answer: b

Explanation: Wooden workpieces of a pattern set to come in circular type which are used for making annular parts and elements having a trough shape.

5. Rectangular wooden workpiece of a pattern set is not used for making?

a) Shields

b) Boards

c) Boxes

d) Drum type elements

Answer: d

Explanation: Drum type elements are made using circular wooden workpiece of a pattern set, while the remaining ones are made out of the rectangular wooden workpiece.

6. Design of pattern elements and method of jointing depend on?

a) Strength

b) Hardness

c) Ductility

d) Brittleness

Answer: a

Explanation: The design of the elements of pattern and its method of joining depends on the strength and the accuracy to which the pattern has to be made.

7. What shape does fillet pieces have?

a) Convex

b) Concave

c) Convex and concave

d) Plane

Answer: b

Explanation: Fillets have different construction for the straight and the corners which are not split. They are made up of milled concave pieces stuck in their position.

8. The following wooden workpiece is which type of pattern set?

casting-questions-questions-answers-entrance-exams-q8

a) Cylindrical

b) Trough shaped

c) Drum-type

d) Rectangular

Answer: d

Explanation: The given figure represents a rectangular wooden workpiece, while the other remaining three are types of cylindrical pattern set.

9. What should the radius of fillet be to allow fillet sharp angles?

a) More than 15mm

b) Less than 10mm

c) Between 10mm and 15mm

d) More than 20mm

Answer: b

Explanation: Radius of the fillet in order to allow filleting sharp angles, must be less than 10mm, in all classes of pattern. If the radius exceeds this value or goes below it, there would be defects in the cast.

10. Mortising does locking at given angles.

a) True

b) False

Answer: a

Explanation: A mortise is a wood working machine, used for mortising tenon joints and the process of locking planks and bars together at a given angle is called as mortising. A mortise can also be used for cutting square holes in wood.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Mold Materials”.

1. Which of the following properties must a material possess to be used in mold making?

a) High refractoriness

b) Chemical and thermal stability

c) High permeability

d) All of the mentioned

Answer: d

Explanation: A material must have all of the above properties so as to be a good mold making material.

2. Which of the following group of material type is used in mold making?

a) Metallic only

b) Non-Metallic only

c) Both metallic as well as non-metallic

d) Neither metallic nor non-metallic

Answer: c

Explanation: Both metallic as well as non-metallic materials are used for making molds.

3. Which of the following non-metallic material is not used in the synthesis of molds?

a) Magnesite

b) Silimanite

c) Zircon

d) Valcanised rubber

Answer: d

Explanation: Valcanised rubber has a very low refractoriness, hence, using valcanised rubber for making molds can cause damage to the mold cavity or metallic structure so formed.

4. High refractoriness of a material refers to its __________

a) Slipperyness of the material

b) Chemical strength towards other material

c) Strength to withstand at high temperature

d) Ability to get dissolved in molten metal

Answer: c

Explanation: Refractoriness is the resistance to self deformation at high working temperatures. A material must possess such property in order to withstand the temperature of molten metal during casting.

5. Which of the following is a perfect composition of clay  used in moulding sand?

a) Al 2 O 3

b) Al 2 O 3 .2SiO 2

c) Al 2 O 3 .2H 2 O

d) Al 2 O 3 .2SiO 2 .2H 2 O

Answer: d

Explanation: Bentonite is one type of clay used in moulding sand as a binder. Its chemical formula is represented as Al 2 O 3 .2SiO 2 .2H 2 O.

6. Which of the following material is not used for mold making?

a) Iron

b) Zinc

c) Mild steel

d) Alloy steel

Answer: b

Explanation: Zinc  has a very low melting point, making it non-dependable material to be used as the material for mold making.

7. Phosphorus is added to steel mold for which of the following reason?

a) It increases strength and hardness of steel

b) It increases refractoriness of steel

c) It increases porosity of steel

d) It increases finishing of steel

Answer: a

Explanation: Phosphorus has the ability to increase strength and hardness of steel material when added to it in the right compostion .

8. Which of the following is a perfect composition for medium carbon steel?

a) Upto 0.3%

b) 0.3-0.6%

c) 0.6-1.7%

d) 1.7-3%

Answer: b

Explanation: The sequence of composition is in order from low carbon steel to high carbon steel till 1.7% carbon. Medium carbon steel belongs to a region of 0.3-0.6% carbon.

9. A form of cast iron in which free carbon is present in the form of nodules in the matrix of cementite and ferrite. This form of cast iron is ____________

a) Malleable iron

b) Pig iron

c) Wrought iron

d) None of these

Answer: a

Explanation: Malleable iron is one type of cast iron in which free carbon is present in the form of nodules in the matrix of cementite and ferrite.

10. Which of the following percent of carbon is correct for Eutectoid steel (at 723 o C in Fe 3 -C diag)?

a) 0.05%

b) 0.5%

c) 0.6%

d) 0.8%

Answer: d

Explanation: At 723 o C in Fe 3 C diagram the transformation change takes place. The carbon content at this point is 0.8% and is called as eutectoid steel.

11. Which of the following is not used as binders for mould materials?

a) Bentonite

b) Kaolinite

c) Backelite

d) Illite

Answer: c

Explanation: Backelite is a material which increases hardness beyond a limit which is acceptable for mold materials as well as its deformation takes place too early as plastic deformation. Hence, it is not used as a binder.

12. Which of the following is not used as an additive?

a) Dextrin

b) Coal dust

c) Pitch

d) Zinc

Answer: d

Explanation: Zinc is an alloying element and is not considered as additive.

13. Which of the following curve is absolute for effect of % of hardness on martensite produced?

a) casting-questions-answers-mold-materials-q13a

b) casting-questions-answers-mold-materials-q13b

c) casting-questions-answers-mold-materials-q13c

d) casting-questions-answers-mold-materials-q13d

Answer: a

Explanation: From the starting of martensite produced the hardness increases with % of carbon present in it but after a certain point this curve tends to remain constant for hardness value with increase in carbon content.

14. Nitriding process is used to increase surface hardness for which of the following materials?

a) Alloy steels

b) Low carbon steels

c) Medium carbon steels

d) High carbon steels

Answer: a

Explanation: Alloy steels  can easily undergo nitriding process.

15. The famous iron pillar located near Qutab Minar in New Delhi is made up of which material?

a) Stainless steel

b) Malleable iron

c) Mild steel

d) Wrought iron

Answer: b

Explanation: Malleable iron is a raw kind of type of iron which was used in the making of Iron pillar.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Molding Sands”.

1. Which of the following is not a source of moulding sand?

a) Sea

b) Lakes

c) Desert

d) Forests

Answer: d

Explanation: There are a variety of soils which can be found in forests. But the soils found there cannot be used for casting purposes. Hence forests are not a source for finding moulding sand, whereas sea, lakes and deserts are a source of finding them.

2. Which of the following is not a type of moulding sand?

a) Red sand

b) Natural sand

c) Synthetic sand

d) Loam sand

Answer: a

Explanation: Red sand is not counted among the moulding sands, whereas natural sand, synthetic sand and loam sand are various other types of moulding sand, which can be effectively used for casting processes.

3. What is the percentage composition of clay in natural sand?

a) 22-31%

b) 3-10%

c) 5-20%

d) 18-29%

Answer: c

Explanation: In natural sands, the percentage composition of clay is approximately 5-20% as the binding material. If the percentage composition is less than that like 3 to 10%, then the binding action will not take place effectively.

4. What is the percentage composition of water in natural sands?

a) 2-4%

b) 5-8%

c) 6-9%

d) 10-13%

Answer: b

Explanation: Water is an important agent used in sands, but its composition should be inside the desired range. The percentage composition of water in natural sands is around 5-8% for mixing before making a mould.

5. What is mixed with natural sand to make it semisynthetic sand?

a) Bentonite

b) Barelelne

c) Cubane

d) Prismane

Answer: a

Explanation: The addition of a material like bentonite in its sand form, is because of the need to enhance the sand properties. Bentonite is mixed with natural sand to make it semisynthetic sand and thus improving its properties.

6. Which sand is used for casting cast irons and non-ferrous metals?

a) Loam Sand

b) Natural Sand

c) Synthetic Sand

d) Refractory sand grain

Answer: b

Explanation: For casting iron and non-ferrous metals, natural sand is used. The loam sand, the synthetic sand and the refractory grain sand do not play any role in casting them.

7. Natural sands are economical than synthetic sands.

a) True

b) False

Answer: a

Explanation: In natural sands, the amount of availability of it is quite abundant, also, there need not be much of further operations on the natural sands unlike synthetic sands. Natural sands involve a much lesser cost as compared to synthetic sands, as lesser control is needed there.

8. What is the amount of clay content in Loam sand?

a) 30%

b) 40%

c) 50%

d) 60%

Answer: c

Explanation: Clay content in loam sand is relatively more than that of in natural sand. Also, the amount of humid content or the levels of water too in loam sand would be differing similarly. The clay content in loam sand is around 50%.

9. Which sand is used for making ferrous and non-ferrous alloys?

a) Natural sand

b) Synthetic sand

c) Loam sand

d) Refractory sand grain

Answer: b

Explanation: Natural sands are used for casting ferrous and non-ferrous metals while synthetic sands are used for casting ferrous and non-ferrous alloys.

10. A general loam sand mixture contains how many volumes of silica?

a) 10

b) 20

c) 30

d) 40

Answer: b

Explanation: In general loam sand, the moisture is found to contain a decently good amount of clay content in it. A general loam sand mixture contains 20 volumes of silica, the moisture of 20% and manure 1 volume.

11. The figure below shows which foundry sand grain shape?

casting-questions-answers-molding-sands-q11

a) Round

b) Sub angular

c) Angular

d) Compound

Answer: c

Explanation: Foundry sand grain is categorised into four types which are, round type, sub-angular type, angular type and compound type. This figure here, depicts angular sand grain.

12. The figure below shows which foundry sand grain shape?

casting-questions-answers-molding-sands-q12

a) Round

b) Sub angular

c) Angular

d) Compound

Answer: a

Explanation: None.

13. Round grain has higher permeability than angular grains.

a) True

b) False

Answer: a

Explanation: Round grains do not have a better bond and possess lesser strength. Round grain has higher permeability than angular strength.

14. The figure below shows which foundry sand grain shape?

casting-questions-answers-molding-sands-q14

a) Round

b) Sub angular

c) Angular

d) Compound

Answer: d

Explanation: None.

This set of Casting Questions and Answers for Freshers focuses on “Molding Sands Binders”.

1. On increasing the binder content, what in the moulding sand gets reduced?

a) Hardenability

b) Strength

c) Permeability

d) Brittleness

Answer: c

Explanation: On increasing the binder content, the hardenability does not get affected. The strength and the brittleness to do not change, but on addition of too much of binder in the moulding sand, the permeability of the moulding sand gets reduced.

2. Which of the following is bentonite?

a) Kaolinite

b) Sodium Montmorillonite

c) Illite

d) Limonite

Answer: b

Explanation: Bentonite sands are one of the most useful additive in casting sands, as it helps in enhancing its properties. Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite.

3. Which of the following is not a clay binder?

a) Limonite

b) Illite

c) Limonite

d) Carsil

Answer: d

Explanation: Carsil is a type of patented binder. Carsil is known to be a product of foseco and is therefore called as foseco-product, while the other three types mentioned above are all different types of clay binders.

4. Clays are what type of binders?

a) Organic

b) Patented

c) Inorganic

d) Other binders

Answer: c

Explanation: Clay binders come under the category of inorganic binders. Clay binders are basically known to provide the casts with some good amount of binding properties and optimum moisture contents.

5. At what temperature does the clay dead burning take place?

a) 400°C – 500°C

b) 500°C – 600°C

c) 600°C – 700°C

d) 700°C – 800°C

Answer: b

Explanation: Clay dead burning is a process that needs to be taken place at a comparatively higher temperature. The temperature at which the clay dead burning takes place is somewhere in between 500°C and 600°C.

6. What is the breadth size range of a clay particle?

a) 0.01-1 micrometres

b) 0.02-2 micrometres

c) 0.03-3 micrometres

d) 0.04-4 micrometres

Answer: a

Explanation: The particles of clay are very small and need high precision microscopes to determine its size. Clay particles in their breadth have a particle size range in between 0.01 micrometres to 1 micrometres.

7. Which of the following clay binders are most commonly used?

a) Bentonite

b) Illite

c) Limonite

d) Kaolinite

Answer: a

Explanation: Bentonite is the most commonly used clay binder because of its ability to produce strong bonds inside the moulding sands. Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite.

8. What is the percentage composition of quartz in Western bentonite?

a) 5%

b) 10%

c) 15%

d) 20%

Answer: b

Explanation: Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite. Western bentonite also called Sodium montmorillonite is known to have a percentage composition 10% of quartz.

9. What is the percentage composition of quartz in Southern bentonite?

a) 5%

b) 10%

c) 15%

d) 20%

Answer: c

Explanation: Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite. Southern bentonite also called as Calcium montmorillonite is known to have a percentage composition 15% of quartz.

10. What is the softening point of western montmorillonite?

a) 800°F – 1150°F

b) 1200°F – 1650°F

c) 1750°F – 2100°F

d) 2100°F – 2450°F

Answer: d

Explanation: Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite. Western bentonite also called as Sodium montmorillonite is known to have its softening point in the range of 2100°F – 2450°F.

11. What is the softening point of western montmorillonite?

a) Above 1800°F

b) Above 2000°F

c) Above 2200°F

d) Above 2400°F

Answer: a

Explanation: Bentonite is classified into 2 types, namely, Sodium montmorillonite and Calcium montmorillonite. Southern bentonite also called as Calcium montmorillonite is known to have its softening point above 1800°F

12. Illite has a softening point of about 4500°F.

a) True

b) False

Answer: b

Explanation: Illite is a decomposition product due to weathering, and is found in natural moulding sands. It has its softening temperature at about 2500°F.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Properties of Moulding Sand”.

1. Which of the following is not a characteristic property of any moulding sand?

a) Flowability

b) Hardenability

c) Green strength

d) Dry strength

Answer: b

Explanation: Flowability, green strength and dry strength are few of the characteristic properties of moulding sand, but not hardenability.

2. What does a mould having adequate green strength, does not have?

a) Ability to retain its shape

b) Ability not to get distorted

c) Ability not to collapse

d) Ability to retain hardness

Answer: d

Explanation: For a mould to be having an adequate amount of green strength, it must have retaining ability or the ability to get distorted or to collapse. A mould having adequate green strength does not have the ability to retain hardness.

3. Dry sand does not have the strength for what functions?

a) To withstand corrosion forces

b) To withstand pressure of molten metal

c) To be able to retain its shape

d) To be able to retain the hardenability

Answer: d

Explanation: Dry sand has its strength for various purposes like, to withstand a pressure of molten metal, to withstand corrosion forces and to be able to retain its shape. But it does not have it for being able to retain the hardenability.

4. Hot strength is seen at what temperature?

a) Above 212°F

b) Above 312°F

c) Above 412°F

d) Above 512°F

Answer: a

Explanation: Hot strength basically is the strength of the sand which is present inside the mould cavity. It is observed that, the hot strength of any material is at 212°F or above it.

5. Which of the following would not happen if hot strength is not enough?

a) The mould may get hardened

b) The mould may get enlarged

c) The mould may get eroded

d) The mould may crack

Answer: a

Explanation: If there is not an adequate amount of hot strength provided, then the mould may get enlarged, the mould may get eroded and the mould may crack, but the mould will not get hardened.

6. Why should the moulding sand be porous?

a) For gases to enter

b) For gases to escape

c) For water to enter

d) For water to escape

Answer: b

Explanation: A moulding sand is the one in which, the sand is known to have holes in it and also it is known for holding some amount of moisture content. A moulding should be having pores and should be permeable so that the gases have a free path for escaping.

7. Which of the following is not a defect if permeability is not enough?

a) Brittleness

b) Gas holes

c) Mould blast

d) Surface blows

Answer: a

Explanation: If the permeability or the porosity is less or the permeability is found to be inadequate or the porosity is found to be absent, then brittleness is not the defect it has, but it may have, gas holes or mould blasts or surface blows.

8. In green sand what is the amount of water used?

a) 5%

b) 10%

c) 15%

d) 20%

Answer: a

Explanation: In green sand, the amount of clay that is needed in percentage composition is around 15% to 30%. The amount of water in terms of percentage composition is about 5%.

9. What is the amount of clay needed in green sand?

a) 5% – 10%

b) 5% – 15%

c) 15% – 30%

d) 25% – 40%

Answer: c

Explanation: In green sand, the amount of clay needed in terms of percentage composition is approximately in between 15% to 30% and the amount of water needed in terms of percentage composition is somewhere around 5%.

10. Parting sand is a type of moulding sand.

a) True

b) False

Answer: a

Explanation: Parting sand is one of the many types of moulding sand which contains silica, sand and burnt sand.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Refractory Sands”.

1. Which of the following is not refractory sand?

a) Olivine

b) Silica Sand

c) Dolomite

d) Barium Chloride

Answer: d

Explanation: Among the following, Barium Chloride is not refractory sand, as it is counted under foundry fluxes, whereas all remaining sands are refractory sands.

2. Which refractory sand has the best moulding material?

a) Silica sand

b) Magnesite

c) Zircon

d) Olivine

Answer: a

Explanation: Silica sands are considered to be having the best moulding material. It has its occurrence in a variety of crystalline modifications.

3. Ganister is another name for which sand?

a) Magnesite

b) Zircon

c) Silica sand

d) Dolomite

Answer: c

Explanation: Ganister is another name for silica sand. As, silica is obtained from carbon-ferrous sandstone, also known as dinas.

4. At what temperature, does quartz melt completely?

a) 1725°C

b) 1925°C

c) 1825°C

d) 2025°C

Answer: a

Explanation: Quartz gets melted completely at 1725°C. After reaching this temperature, the quartz would then start undergoing transformations.

5. Which of the following is the most porous sand?

a) Silica sand

b) Zircon

c) Olivine

d) Dolomite

Answer: a

Explanation: Even when the silica sand are packed as mould cavity, they show enough porosity and permeability, and hence are porous sands.

6. At what temperature does the silica sand start expanding thermally?

a) 918°F

b) 843°F

c) 1063°F

d) 1124°F

Answer: c

Explanation: It is one of the disadvantages of silica sand, that it has its thermal expansion temperature at 1063°F. At this temperature, the volume of the sand starts to increase.

7. Which of the following factor is not to be considered while selecting a refractory?

a) Conductivity

b) Expansion

c) Size of the particle

d) Permeability

Answer: d

Explanation: Conductivity, thermal expansion and size of the particle are few of the factors needed to be considered while selecting a refractory and not permeability.

8. Which sand is generally used repetitively for mould making?

a) Silica sand

b) Zircon

c) Olivine

d) Dolomite

Answer: a

Explanation: Silica sand has this as one of its advantages, that it can be used again and again for making moulds. This repetitive use of silica sand makes production even more inexpensive.

9. Which of the following sand is freely available?

a) Silica sand

b) Zircon

c) Olivine

d) Dolomite

Answer: a

Explanation: Silica sand has this as one of its advantages, that it is available without any difficulty in abundance. Hence, the cost of silica sand is also low.

10. Silica sand is expensive.

a) True

b) False

Answer: b

Explanation: Silica sand is most freely available, without any difficulty in abundance. Hence, the cost of this sand is low.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Grain Size and Shape”.

1. The size and shape of particles in the soil cannot reflect material composition and grain formation.

a) True

b) False

Answer: b

Explanation: The size and shape of particles in the soil reflect the material composition and grain formation. And also include the escaping from a mineral matrix and depositional environments. The common processes involve the formation of small and large size grains in the soil mixture which is used for making mould.

2. The grain size distribution of soil basically determines inter-particle forces and its packing.

a) True

b) False

Answer: a

Explanation: Soil is mainly made of grains which size distribution estimates the particle-level forces and the inter-particle packing. Hence, the grain size distribution plays a vital role in the soil systems. The shape of grain is classified at the three different parameters which are global form, surface features and surface roughness.

3. Quartz grains are generally fine or small in shape and size during analysis of quartz.

a) True

b) False

Answer: b

Explanation: Quartz grains are generally coarse in size during analysis of quartz which is greatly affected by the solidification of quartz in the igneous rocks. The shape and surface characteristics reflect the mechanical and chemical effects after the releasing of grains. From chemical to mechanically controlling of shape, the transition part occurs between the particles of 50mm to 400mm size.

4. Large particles in soil increase the chances of imperfection and brittle failure.

a) True

b) False

Answer: a

Explanation: The Large particles in soil increase the chances of imperfections and brittle failure. Reversely, smaller particles are strengthened by the decrease in imperfections. This makes the failure advantageous that occurs due to the presence of cleavage at the crystal planes. High cooperating conditions increases the breaking of extended particles and shear abrasion.

5. Which of the following equipment can be used for determining the grain size of soil particles?

a) Sprue

b) Gate

c) Runner

d) Sieve

Answer: d

Explanation: Analysis of grain size of soils particles containing mostly large size particles is completed by using sieves. It is a device which normally consists of openings of same size and shape through which grains or particles of soil passes which should be smaller in size as compared to the size of openings, and the very large particles retained on the sieve.

6. Analysis of very small size grains of soil can also be possible by using sieves.

a) True

b) False

Answer: b

Explanation: Analysis of very small size grains of soil cannot be possible by using sieves, because of very small size of sieve openings, it is very difficult to get pass the grains. Then for the analysis of small size grains, hydrometer analysis is done which is based on stoke’s law that states that the larger the grain size, the larger it’s settling speed in a fluid.

7. In a hydrometer test, a dispersing agent is mixed with water to increase its density.

a) True

b) False

Answer: a

Explanation: For the analysis of small size grains of soil, a hydrometer test is performed in which a dispersing agent is used which blended with water to increase its specific gravity that indicates an increase in density of liquid. It also affects the variation of temperature of the liquid from the hydrometer calibration temperature.

8. It becomes easier to read the bottom part of the meniscus when the hydrometer is in a soil suspension.

a) True

b) False

Answer: b

Explanation: It is impossible to read the bottom part of the meniscus when the hydrometer is in a soil suspension. In the hydrometer test, it is very necessary or essential to form a graph or table that gives a composite correction as a function of temperature for the present of dispersing agent in the hydrometer.

9. In a hydrometer test, soil used should be dispersed first in order to eliminate particle coagulation.

a) True

b) False

Answer: a

Explanation: For the analysis of small size grains of soils in hydrometer test, soil sample used should be dispersed first in order to eliminate the particle coagulation. This is mainly accomplished by blending of soil with the solution of sodium hexametaphophate and then stirring is done to get a proper uniform solution.

10. The grain size distribution is mainly carried out to determine the strength and permeability of the soil.

a) True

b) False

Answer: a

Explanation: The grain size distribution is fundamental for determining the properties of soil. It is mainly carried out for the classification of soil and to estimate the engineering properties like strength, permeability, compressibility and shear strength. Practically, the grain size distribution of soil is obtained by integrating the data gained from tests like mechanical sieving and hydrometer testing.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Bonding Theory”.

1. Which of the following is not a bonding theory?

a) Electrostatic bonding theory

b) Hot strength theory

c) Surface tension theory

d) Block and wedge theory

Answer: b

Explanation: Hot strength theory is not one of the bonding theories, while electrostatic theory, surface tension theory and block and wedge theory are bonding theories.

2. In which of the following bonding theory, water molecules break down to form H+ and OH- ions?

a) Electrostatic bonding theory

b) Hot strength theory

c) Surface tension theory

d) Block and wedge theory

Answer: a

Explanation: In electrostatic bonding theory, water is mixed in clay and sand grains, these water molecules then break into H + ions and OH – ions.

3. What does the clay particle absorb in electrostatic bonding theory?

a) Complete water

b) H + ions

c) OH – ions

d) Sand grains

Answer: c

Explanation: The OH – ions are basically the base ions. The clay particles in electrostatic bonding theory, absorb the OH – ions because of the not satisfied valence bond.

4. For bonding action of clays, what is the amount of water needed?

a) 1.5%-8%

b) 3.5%-11%

c) 4.5%-12%

d) 5.5%-13%

Answer: a

Explanation: For the bonding action of the clays, water is needed, which activates the sand and clay-sand mixture. The amount needed for this is 1.5% to 8%.

5. What is the amount of sea coal needed in cast irons for small casting moulding sands?

a) 1%

b) 2%

c) 3%

d) 4%

Answer: a

Explanation: In bonding of substances, an extremely small quantity of sea coal is also needed. Sea coal is used for surface appearance improvement. It is used about 1% in cast iron moulding sands for small castings.

6. What is the amount of sea coal needed in cast irons for large green casting moulding sands?

a) 10%

b) 15%

c) 20%

d) 25%

Answer: a

Explanation: Sea coal otherwise is used in small numbers for binding. Sea coal is used for surface appearance improvement. It is used about 10% in cast iron moulding sands for large green casting sands.

7. At what temperature is pitch distilled from soft coals?

a) 400°F

b) 500°F

c) 600°F

d) 700°F

Answer: c

Explanation: For pitch distillation of soft coals, a decently high temperature level has to be attained. From soft coal, pitch is distilled at a temperature of around 600°F and a by-product called Asphalt is produced.

8. Pitch maybe used up to what percent?

a) 1%

b) 2%

c) 3%

d) 4%

Answer: b

Explanation: Pitch distillation of soft coals plays a vital role in bonding theory. Pitch is used for getting a good surface finish on iron casts. These pitches generally are used up to be to 2%.

9. Which of the following increases the dry strength of the sand?

a) Iron oxides

b) Fuel oils

c) Cereals

d) Dextrin and molasses

Answer: d

Explanation: Dextrin and molasses are used for increasing the dry strength of the sand, which add hardness to the mould.

10. Cereals improve flowability and lower collapsibility.

a) True

b) False

Answer: b

Explanation: Cereals do not improve flowability, as a matter of fact, it reduces it, and, cereals are not known to reduce or not the collapsibility, in fact it is known to improve it.

11. How much should fuel oil be added to increase the moulding ability of sand?

a) 0.01% – 0.1%

b) 0.02% – 0.2%

c) 0.03% – 0.3%

d) 0.04% – 0.4%

Answer: a

Explanation: Fuel oils are known to have great properties in them. Fuel oils are helpful in adding to the increase of the moulding ability of sand. It can be added in the range of 0.01% to 0.1%.

This set of Casting Questions and Answers for Campus interviews focuses on “Fire Clays, Illite and Kaolinite”.

1. Which of the following materials presents in clay which imparts plasticity in it?

a) Silica

b) Phyllosilicates

c) Calcium

d) Sodium

Answer: b

Explanation: Clay generally contains phyllosilicates which are mainly responsible for imparting plasticity in the clay material. It can also include other materials which impart plasticity and harden-ability when the clay is dried or fired. Combined phases in clay material can also contain materials that do not impart any plasticity.

2. Which of the following components of soil are acts as chemical sponges in the soil?

a) Clay minerals

b) Silica

c) Sodium

d) Potassium

Answer: a

Explanation: Clay minerals are quite stable and are an important part of the soil. Clay minerals are also called as chemical sponges which basically hold water content and dissolved nutrients from other mineral particles. This results due to the presence of unstable electric charges on the surface of clay particles, in which opposite charges attract to each other.

3. The attraction of clay minerals with water is a surface phenomenon which is called absorption.

a) True

b) False

Answer: b

Explanation: Clay minerals have the ability to attract water particles and this attraction is a surface phenomenon which is called as adsorption, which is completely different from absorption process because the ions and water molecules do not get inside the clay particles and they remained to adhere to the clay grains, that’s why the process is called as adsorption.

4. Kaolinite clay mineral generally adsorbs fewer ions than that of other clay minerals.

a) True

b) False

Answer: a

Explanation: Kaolinite clay mineral is a weathering product of feldspars and it commonly has white and powdery appearance. Kaolinite name is derived from a region named kaolin in china using the local clay mineral. It is extensively used in ceramics industries because it is electrically balanced but adsorbs fewer ions than that of other clay minerals.

5. The layer structure of kaolinite mineral totally consists of three tetrahedral silicate sheets.

a) True

b) False

Answer: b

Explanation: The kaolinite minerals normally include kaolinite, nacrite and halloysite which are the most common but important clay minerals in nature that are widely used in industries. They consist one to one layered structure, in which each layer include one tetrahedral silicate sheet and one octahedral silicate sheet.

6. Which of the following members of clay minerals is formed by the decompositions of micas?

a) Chlorite

b) Illite

c) Kaolinite

d) Vermiculite

Answer: d

Explanation: Vermiculite is a very important and essential member of clay minerals which is normally formed by the decompositions of micas and occurs as completely large crystals of mica like appearance. It has a layer structure which basically consists of water particles and exchangeable cations which are mainly magnesium ions.

7. Which of the following types of clay mineral includes potassium in the layer structure?

a) Chlorite

b) Vermiculite

c) Illite

d) Kaolinite

Answer: c

Explanation: Illite is a clay mineral which has potassium in the interlayer structure. The size and coordination number of potassium are like that it fits tightly in the hexagonal ring of oxygen of the tetrahedral sheets. This makes the structure a strong interlocking ionic bond which packs the individual layers together and restricts the water particles from immersing the interlayer site.

8. Palygorskite and sepiolite clay minerals generally have similar fibrous structures.

a) True

b) False

Answer: a

Explanation: Palygorskite and sepiolite clay minerals have similar fibrous structures or morphologies, but palygorskite shows more structural variety. Both the clay minerals are magnesium silicates, but palygorskite has less magnesium and more aluminium than sepiolite. Structurally, both the clay minerals include blocks and ribbon like sheets extending in a specific direction.

9. Ball clay is a type of clay which has zero percent moisture or water content in it.

a) True

b) False

Answer: b

Explanation: Ball clay normally has water content nearly about 28 percent. To decrease moisture content, they are stored in drying sheds. Then the clay is shredded into small pieces which are further dried by the use of hammer mill. Extracted scrap material from the hammer mill is blended with water to form a slurry mixture for further use.

10. Repeated freezing and melting of fire clay can improve the plasticity of the clay material.

a) True

b) False

Answer: a

Explanation: First the fire clay is taken to the processing plant and then weathered for a long period of time, depending on the type of fire clay. Freezing and melting break the clay material and results in improved plasticity. Then the clay material is crushed and dried in mechanical dryers to remove the moisture content. Mostly, the rotary dryers fired with natural gas are used for drying the fire clay.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Molding Sand Mixtures For Casting”.

1. In the green sand moulding of steel casting, what is the bentonite percentage composition?

a) 1.5%

b) 2.5%

c) 3.5%

d) 4.5%

Answer: c

Explanation: In green sand mouldings of steel castings, the dextrin percentage is quite lower, it is around 0.5%. The bentonite percentage composition in green sand molding is calculated to be 3.5%.

2. In the green sand moulding of steel casting, what is the dextrine percentage composition?

a) 0.5%

b) 1.5%

c) 2.5%

d) 3.5%

Answer: a

Explanation: In green sand mouldings of steel castings, the dextrine percentage composition is calculated to be 0.5% and the bentonite percentage in the same green sand is higher than dextrin by around 3%.

3. In the green sand moulding of steel casting, what is the moisture percentage composition?

a) 1% – 2%

b) 2% – 3%

c) 3% -4%

d) 4% – 5%

Answer: c

Explanation: In green sand mouldings of steel castings, the moisture percentage composition is calculated to be 3%- 4% and the amount of bentonite present in the same green sand is around 3.5%.

4. In dry sand moulding of steel casting, what is the bentonite percentage composition?

a) 1%

b) 2%

c) 4%

d) 5%

Answer: d

Explanation: In dry sand mouldings of steel castings, the bentonite percentage composition is calculated to be 5% and in green sand, the bentonite percentage is calculated to be 3.5%.

5. In dry sand moulding of steel casting, what is the dextrine percentage composition?

a) 0.5%

b) 1.5%

c) 2.5%

d) 3.5%

Answer: a

Explanation: In dry sand mouldings of steel castings, the dextrine percentage composition is calculated to be 0.5%. In green sands, the dextrin content is also 0.5%, which is in green sand and in dry sand, the percentage of dextrine is same.

6. In green sand moulding of steel casting, what is the moisture percentage composition?

a) 2-3%

b) 3-4%

c) 4-5%

d) 5-6%

Answer: d

Explanation: In dry sand mouldings of steel castings, the moisture percentage composition is calculated to be 5-6%. In green sands, the moisture content is relatively lower than dry sands. It is around 3% to 4%.

7. In synthetic sands of aluminium alloys, what is the bentonite percentage composition?

a) 2-5%

b) 3-5%

c) 4-5%

d) 5-6%

Answer: c

Explanation: In synthetic sands of aluminium alloys, the bentonite percentage composition is calculated to be 4-5%. Whereas, in the case of green sands, the bentonite percentage is recorded to be around 3.5%.

8. In gray iron castings of facing sand mixtures, what is the bentonite percentage composition?

a) 2-3%

b) 3-4%

c) 4-5%

d) 5-6%

Answer: a

Explanation: In gray cast irons of facing sand mixtures, the bentonite percentage composition is calculated to be 2-3%. Whereas, in the case of green sands, the bentonite percentage is recorded to be around 3.5%.

9. In magnesium alloys, what is the bentonite percentage composition?

a) 1%

b) 2%

c) 3%

d) 4%

Answer: d

Explanation: In magnesium alloys, the bentonite percentage composition is calculated to be 4%. Whereas, in the case of green sands, the bentonite percentage is recorded to be around 3.5%.

10. In magnesium alloys, the water content in percentage is 10%.

a) True

b) False

Answer: b

Explanation: In magnesium alloys, the water content in terms of percentage is not 10%. The amount of water in terms of percentage composition is much lower than that. The composition of water around 2%.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Indian Sand And Core Sand”.

1. Foundry sands cannot be obtained in which of the following states?

a) Uttar Pradesh

b) Punjab

c) Orissa

d) Bihar

Answer: d

Explanation: Foundry sand is found to be available in many parts of India like Uttar Pradesh, Punjab and Orissa, but it is not available in the state of Bihar.

2. Foundry sand is found in which part of Maharashtra?

a) Satara

b) Mumbai

c) Nagpur

d) Nasik

Answer: a

Explanation: Foundry sand is available in Maharashtra, but it is not available in all parts of the state. It is found only in the parts of Satara.

3. Which of the following is not a core sand property?

a) Dry strength

b) Hardness

c) Low collapsibility

d) Good Permeability

Answer: c

Explanation: Dry strength, hardness and a good amount of permeability are a few properties of core sand. Low collapsibility is not any of the property of core sands, in fact, core sands are supposed to have high collapsibility.

4. Good friability is one of the properties of core sand.

a) True

b) False

Answer: a

Explanation: Good friability is one of the properties of the core sand so that the core falls away when it is to be removed from castings.

5. Which of the following is not a core sand ingredient?

a) Water

b) Wax

c) Granular refractories

d) Core binders

Answer: b

Explanation: For the core material, water, granular refractories and core binders are ingredients which are highly used. The ingredients used do not involve wax in it and hence is not a part of the ingredients.

6. What is the melting point of Zircon?

a) 3450°F – 4620°F

b) 3750°F – 4820°F

c) 3850°F – 4820°F

d) 4400°F – 5320°F

Answer: a

Explanation: According to the properties of granular refractories, Zircon has a melting point temperature of 3450°F to 4620°F. Zircon is a kind of material which does not show much changes in physical aspects on exceedingly high temperatures.

7. What is the melting point of Olivin?

a) 3450°F – 4620°F

b) 3200°F – 3450°F

c) 3100°F – 3220°F

d) 3400°F – 3620°F

Answer: b

Explanation: According to the properties of granular refractories, Olivin has a melting point temperature of 3200°F to 3450°F. Olivin is one of the materials which do not change its state at low temperatures.

8. What is the melting point of Chamotte?

a) 3450°F – 4620°F

b) 3200°F – 3450°F

c) 3100°F – 3200°F

d) 3400°F – 3620°F

Answer: c

Explanation: According to the properties of granular refractories, Chamotte has a melting point temperature of 3100°F to 3200°F. The melting point of chamotte is comparatively lower than zircon and olivin.

9. What is the melting point of Silica, for granular refractories?

a) 3453°F

b) 3206°F

c) 3119°F

d) 3467°F

Answer: c

Explanation: According to the properties of granular refractories, Silica has a melting point temperature of 3119°F. The melting points of silica and chamotte are calculated to be almost equal.

10. For the granular refractories, what is the melting point of Carbon?

a) 6800°F

b) 6200°F

c) 6400°F

d) 6500°F

Answer: c

Explanation: According to the properties of granular refractories, Carbon has a melting point temperature of 6400°F. Among all the granular refractories, the melting point of carbon is considered to be the highest.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Preparation Of Core Mix”.

1. How much time does a centrifugal muller take to mix the core ingredients?

a) 20 – 50 seconds

b) 10 – 40 seconds

c) 50 – 80 seconds

d) 60 – 90 seconds

Answer: d

Explanation: A centrifugal muller takes around 60 seconds to 90 seconds to get the core ingredients mixed properly, whereas a normal muller takes about 4 minutes for mixing the ingredients.

2. How much time does a normal muller take to mix the core ingredients?

a) 2 – 5 minutes

b) 3 – 6 minutes

c) 4 – 7 minutes

d) 5 – 9 minutes

Answer: b

Explanation: A normal muller takes around 3 minutes to 6 minutes to get the core ingredients mixed properly, whereas a centrifugal muller takes around 30 seconds to one minute to mix the core ingredients.

3. What is the baked tensile strength of light to medium size malleable iron castings?

a) 4.5 kg/cm 2

b) 5.5 kg/cm 2

c) 6.5 kg/cm 2

d) 7.5 kg/cm 2

Answer: b

Explanation: There are many types of cast irons which have differing properties, according to the type of manufacture and the quantity of ingredients used. The baked tensile strength of light to medium size malleable iron casts is 5.5 kg/cm 2 .

4. What is the dry tensile strength of core sand mixture for general purpose?

a) 15 kg/cm 2

b) 16 kg/cm 2

c) 17 kg/cm 2

d) 18 kg/cm 2

Answer: c

Explanation: There are various properties of core sand mixture which widely depend on many factors. The dry tensile strength of core sand mixture for general purpose is 17 kg/cm 2 .

5. What is the dry compression strength of core sand mixture for general purpose?

a) 50 kg/cm 2

b) 60 kg/cm 2

c) 70 kg/cm 2

d) 80 kg/cm 2

Answer: c

Explanation: The dry compression strength of core sand mixture for general purpose is 70 kg/cm 2 , and the dry tensile strength of the of a core sand mixture is calculated to be 17 kg/cm 2 .

6. What is the green compression strength of core sand mixture for general purpose?

a) 1/5 kg/cm 2

b) 1/6 kg/cm 2

c) 1/7 kg/cm 2

d) 1/8 kg/cm 2

Answer: c

Explanation: The green compression strength of core sand mixture for general purpose is 1/7 kg/cm 2 , whereas the dry compression strength of a core sand mixture is found to be 70 kg/cm 2 .

7. What is the green compression strength of light to medium size malleable iron castings?

a) 0.05 kg/cm 2

b) 0.06 kg/cm 2

c) 0.07 kg/cm 2

d) 0.08 kg/cm 2

Answer: d

Explanation: The green compression strength of light to medium size malleable iron casts is 0.08 kg/cm 2 , whereas the dry compression strength of a core sand mixture is found to be 70 kg/cm 2 .

8. What is the water content in light to medium size malleable iron castings?

a) 3.2%

b) 4.2%

c) 5.2%

d) 6.2%

Answer: b

Explanation: The water content in terms of percentage composition in light to medium size malleable iron castings is calculated to be not much in it. The amount of water content found in the casting is about 4.2%.

9. What is the amount of green permeability in light to medium size malleable iron castings?

a) 34 cc/min

b) 44 cc/min

c) 54 cc/min

d) 64 cc/min

Answer: b

Explanation: The rate of green permeability is quite a decent one. The amount of green permeability in light to medium size malleable iron castings is 44 cc/min.

10. In light to medium size malleable iron castings, lake sand constitutes of 30 parts.

a) True

b) False

Answer: b

Explanation: In light to medium size malleable iron castings, lake sand constitutes only 20 parts and bank sand constitutes to 75 parts.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Molding Sand Preparation”.

1. In sand preparation, which of the following is not used as an additive?

a) Clay

b) Cereal

c) Wax

d) Moisture

Answer: c

Explanation: Among the following, clay and cereals are binders, hence used. Moisture too is needed for sand preparation, but in case of wax, it is not counted among additives.

2. Which of the following process deals with the amount of moisture to be added?

a) Sand mixing

b) Sand preparation

c) Sand conditioning

d) Sand tempering

Answer: d

Explanation: Sand tempering is linked with sand preparation, wherein the amount of moisture needed as an additive is added.

3. Which of the following process deals with preparation the mold sand?

a) Sand mixing

b) Sand preparation

c) Sand tempering

d) Sand conditioning

Answer: d

Explanation: Among sand mixing, sand preparation, sand tempering and sand conditioning, the process that deals with preparation of the mold sand is sand conditioning.

4. Which of the following process deals with mixing the molding sand elements?

a) Sand mixing

b) Sand preparation

c) Sand tempering

d) Sand conditioning

Answer: b

Explanation: In sand preparation, the process which is dealing with the basic preparation of mold sand is called as sand conditioning. The mixing of molding elements of sand is dealt by the process called sand preparation.

5. What is the temperature requirement of sand, for manufacturing?

a) Below 40°C

b) Below 50°C

c) Below 60°C

d) Below 70°C

Answer: a

Explanation: Among the basic conditions of sand, temperature condition is considered an essential factor. The temperature requirement of sand used for manufacturing should be below 40°C.

6. To avoid difficulties in making of molds, sand should be cooled below what temperature?

a) 100°F

b) 120°F

c) 140°F

d) 160°F

Answer: a

Explanation: In sand preparation, the requirement of temperature for production is less than 40°C. The said sand, being used for manufacturing, should be cooled down below 100°F to avoid later difficulties in making the molds.

7. What should be the accuracy of automatic moisture control for manufacturing sands?

a) ± 0.1%

b) ± 0.2%

c) ± 0.3%

d) ± 0.4%

Answer: a

Explanation: In any system, the accuracy in its working is considered to be one of the most essential features of that process. The accuracy of automatic moisture control for manufacturing sand must be ± 0.1%.

8. A low speed muller is used in mechanized foundries.

a) True

b) False

Answer: b

Explanation: In mechanized foundries, a high speed muller is essentially used which rotates in a horizontal direction.

9. How much time is taken by sand, for sand preparation in terms of muller time?

a) 33 to 50 percent of muller time

b) 14 to 29 percent of muller time

c) 25 to 40 percent of muller time

d) 46 to 62 percent of muller time

Answer: a

Explanation: Muller time is the time needed for the high speed muller to complete its function. For sand preparation, approximately 33 to 50 percent of muller time is needed.

10. Air blasts are provided for forced cooling of sand after muller operation.

a) True

b) False

Answer: a

Explanation: Mullers usually need approximately 33 to 50 percent of mulling time. In a high speed sand preparation unit, after the muller operation is complete, to cool the sand, air blasts are used.

This set of Casting Interview Questions and Answers for freshers focuses on “Testing of Molding Sand”.

1. High moisture causes what in molding sands?

a) Increase in permeability

b) Decrease in permeability

c) Increase in hardness

d) Increase in strength

Answer: b

Explanation: Permeability is basically the magnitude of pores present in the sands and its capacity of moisture it can hold. High moisture content causes a decrease in permeability of the sand and hence causes other problems in it.

2. The pressure of which gas gives the reading of water content on the pressure gauge?

a) Methane

b) Acetone

c) Acetylene

d) Carbon dioxide

Answer: c

Explanation: Methane, carbon dioxide and acetone are not very useful when it comes to take readings on the pressure gauge. Acetylene gas helps in getting a direct reading on the pressure gauge of the water content.

3. Calcium carbide reacts with moisture to give out which gas?

a) Acetylene gas

b) Methane

c) Carbon dioxide

d) Carbon monoxide

Answer: a

Explanation: According to the chemical reaction, Calcium carbide when reacts with moisture, that is water, it is observed to give out calcium hydroxide and acetylene gas.

4. In a moisture content test, what amount of prepared sand is placed on the pan?

a) 10-40 grams

b) 20-50 grams

c) 30-60 grams

d) 40-70 grams

Answer: b

Explanation: When the tests for composition present in the pan are taken, sands are a very important factor in it. In a moisture content test, approximately 20 grams to 50 grams of prepared sand is taken in the pan.

5. In a moisture content test, how is the prepared sand heated?

a) Flame heating

b) Ultraviolet heating

c) Infrared heating

d) Conduction heating

Answer: c

Explanation: In a moisture content test, the prepared sand is taken in a pan, about 20 to 50 grams, and then heated using infrared heating.

6. In a moisture content test, for how long should the sand in infrared heating bulb be heated?

a) 1 – 2 minutes

b) 2 – 3 minutes

c) 3 – 4 minutes

d) 4 – 5 minutes

Answer: b

Explanation: The moisture content tests are highly performed in a heating bulb. About 20 to 50 grams of the prepared sand is heated using infrared heating for 2 to 3 minutes in the infrared heating bulb.

7. In clay content determination of molding sand, which is the base solution used?

a) KOH

b) NaOH

c) Mg 2

d) Ca 2

Answer: b

Explanation: For knowing the exact details of the compositions present in the sand, various tests have to be performed. In clay content determination of the molding sand, 3% sodium hydroxide  is used.

8. How much distilled water is added to 3% NaOH solution in clay content determination of molding sand?

a) 450 cc

b) 475 cc

c) 500 cc

d) 550 cc

Answer: b

Explanation: A strong base is used in the clay content determination, like sodium hydroxide. 475 cc of distilled water is added to 3% NaOH solution on the determination of clay content of molding sands.

9. Grain distribution is not determined by the Grain fineness test.

a) True

b) False

Answer: b

Explanation: For knowing the exact details of the compositions present in the sand, various tests have to be performed, one of them is grain fitness test. Grain fineness test determines the grain size, grain distribution and grain fineness.

10. Permeability of molding sand does not depend on which of the following factors?

a) Grain distribution

b) Degree of ramming

c) Binder contents

d) Amount of wax present

Answer: d

Explanation: Permeability of molding sand allows the hot gases and steams to escape out. This property does not depend on the amount of wax present.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Different Functions of Core”.

1. Which of the labeled part of the following diagram is a core?

casting-questions-answers-different-functions-core-q1

a) a

b) b

c) c

d) d

Answer: c

Explanation: A core is that element which is used in moulding processes to make hollow cavities or holes or to give special contours on the casting which are difficult or expensive to be machined.

2. Which of the following is not a function of a core?

a) It is used to form internal cavities

b) It is used to form a part of green sand mould

c) It is used as a part of gating system

d) It is used as a part of furnace

Answer: d

Explanation: All of the above functions are that of a core except that the core is never a part of the furnace. somehow it may be used to a path to enhance the flow of molten metal.

3. Cores are subjected to severe thermal and mechanical conditions.

a) Completely true

b) Partially true

c) Completely false

d) Partially false

Answer: a

Explanation: Due to the direct pouring of molten metal  the cores are subjected to severe thermal and mechanical conditions and proper steps must be taken to avoid pattern or mold spoliation.

4. Which of the following is a function of a core in casting?

a) Interior cavitational passages in a casting

b) To shape an external part of a more intricate casting

c) To strengthen and improve inner and outer surface of the mold

d) All of the mentioned

Answer: d

Explanation: A core has versatility of its functions, all the listed functions a core can perform. Moreover, a core has more functions as well.

5. A permeability of a core should be _________

a) Low

b) Moderate

c) High

d) Has no effect on casting

Answer: c

Explanation: The permeability of the material should be high so as to ease the flow of fluids through it during solidification, may work as gas exchanger or water absorber.

6. If a web of internal passageways and chambers is to be constructed which of the following element is most obsolete for use?

a) Cores

b) Core prints

c) Core boxes

d) Chaplets

Answer: a

Explanation: Core has a variety of uses. For the making of long passageways in a casting core a best suitable and cheap.

7. Which of the following statement is true?

a) Cores are permanent

b) Cores are semi-permanent

c) Cores are permanent & semi-permanent

d) Cores are not permanent

Answer: c

Explanation: Cores can be permanent and sometimes they can also be semi-permanent and are destroyed in order to remove the casting from mold.

8. Why are core prints added to the patterns when cores are used?

a) They provide different cooling rates to the core

b) They provide support to the cores and strength to the mould and core itself

c) They are used to ease the removal of a core

d) They are used to manufacture cores

Answer: b

Explanation: Core prints provide support to the cores which are not stable by themselves.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Making the Cores”.

1. Which of the following is not a core machine?

a) Jolt machine

b) Core blower

c) Sand slinger

d) Mill setter

Answer: d

Explanation: Among the following, mill setter is not any type of a core machine, while the other three are few of the types of core machine.

2. Which cores are made manually in hand filled core boxes?

a) Small sized-mass production

b) Small sized-limited production

c) Large sized-mass production

d) Large sized-limited production

Answer: b

Explanation: Small sized cores are made manually in the hand filled core boxes. For making large sized products for mass production, these cores cannot be employed.

3. Weak cores are reinforced using what?

a) Iron wires

b) Steel wires

c) Bronze wires

d) Cobalt wires

Answer: b

Explanation: Weak cores need to be strengthened. And hence, for this purpose, reinforcement is provided, in the form of steel wires.

4. In shell core making, the core box is heated up to what temperature?

a) 400°F – 600°F

b) 500°F – 700°F

c) 600°F – 800°F

d) 800°F – 1000°F

Answer: a

Explanation: A decent amount of temperature has to be attained for the operation of shell core making. In shell core making, the core box has to be heated to a temperature of almost 400°F – 600°F.

5. The following figure represents what?

casting-questions-answers-making-cores-q5

a) Strickle core box

b) Gang core box

c) Left and right hand core boxes

d) Loose piece core box

Answer: c

Explanation: The following figure represents two core boxes, in which one is facing to the right, while the other is facing is towards the left. Hence, it depicts left and right hand core boxes.

6. What does the following figure represent?

casting-questions-answers-making-cores-q6

a) Half core box

b) Split core box

c) Gang core box

d) Loose piece core box

Answer: a

Explanation: The following figure represents a half core box. This type of core box is mainly used for the production of cores which are cylindrical in shape.

7. Which core box is represented by the following figure?

casting-questions-answers-making-cores-q7

a) Half core box

b) Dump core box

c) Split core box

d) Gang core box

Answer: b

Explanation: The given figure represents a dump core box which is used for making rectangular or trapezoidal cores.

8. What does the following figure represent?

casting-questions-answers-making-cores-q8

a) Sand slinger

b) Core extrusion machine

c) Pattern and core prints

d) Core blowing machine

Answer: c

Explanation: The following figure represents pattern and core prints. These core prints make up core seats when they are put into the sand for making mold.

9. A sand slinger works at a high speed.

a) True

b) False

Answer: a

Explanation: A sand slinger uses a high speed rotating impeller which is used for throwing sand in the core box.

10. Cylindrical cores are made using Dump core boxes.

a) True

b) False

Answer: b

Explanation: Dump core boxes are helpful in making rectangular or square cores. Cylindrical cores are made using half core boxes.

This set of Casting Questions and Answers for Experienced people focuses on “Baking the Cores”.

1. Which of the following equipment is used for both limited and mass production?

a) Core ovens

b) Dielectric bakers

c) Radiant bakers

d) Flame bakers

Answer: a

Explanation: Core ovens are the equipment which can be used for the making of limited productions. It is also a good choice if the production is going to be a mass one.

2. After preparation of cores, cores on the core plates are sent for what?

a) Pressurizing

b) Baking

c) Increasing the volume

d) Decreasing the volume

Answer: b

Explanation: Baking is a process that takes place after quite a lot of preliminary operations. After the cores are prepared, the cores are then placed on the plates and moved forward for baking.

3. What does the following figure represent?

casting-questions-answers-experienced-q3

a) Core plate

b) Core drier

c) Core oxidizer

d) Core rack

Answer: b

Explanation: The given figure is a core drier. It is a wooden piece which is having a semi circular groove used for supporting a round core.

4. Cores are baked up to what temperature?

a) 600°F

b) 650°F

c) 700°F

d) 750°F

Answer: b

Explanation: Before the beginning of the process, the cores need to be taken to a decently good amount of temperature by preheating them. While baking the cores, the cores are taken up to a temperature as high as 650°F.

5. The moisture of the core is taken off during baking at what temperature?

a) 197°F

b) 212°F

c) 278°F

d) 304°F

Answer: b

Explanation: None.

6. Core oil and binders change their chemical properties at what temperature?

a) 200°F – 300°F

b) 300°F – 400°F

c) 400°F – 500°F

d) 500°F – 600°F

Answer: c

Explanation: Whenever any material is heated to a temperature high for its properties, there is a change in its chemical and physical aspects seen. Core oils and organic binders used in backing the core, change their physical properties at 400°F – 500°F.

7. What does an unbacked core generate?

a) Greenhouse gases

b) Mold gases

c) Mold liquids

d) Ultraviolet rays

Answer: b

Explanation: An unbacked core causes to generate an excessive amount of mold gases which then produce blowholes in the castings.

8. Using what are core ovens heated?

a) Gases or oils

b) Infrared heating

c) Ultraviolet heating

d) Solar heat

Answer: a

Explanation: Core ovens are heated in a well-defined temperature range. They are heated using gases and other oils.

9. Drawer type core ovens are used for baking large sized cores.

a) True

b) False

Answer: b

Explanation: Drawer type core ovens are used for baking small sized cores. These types of core ovens need proper fuel to be able to energize it to work, hence, they use gas or oil-fuels.

10. Which of the following type of air is circulated over rack type core oven?

a) Cool air

b) Hot air

c) Compressed air

d) Odourless air

Answer: b

Explanation: On a rack type core oven, for proper baking of the core, hot air is circulated over the cores. Odourless air or compressed air or cool air cannot be of much help here.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Finishing of Cores”.

1. How are core manufactured in casting?

a) Cores are manufactured from a pattern in the same way as of mold

b) Cores are manufactured by machining process

c) Cores are manufactured by traditional methods

d) Cores are not manufactured, they are found naturally

Answer: a

Explanation: The manufacturing of cores is similar to mold making and ramming.

2. What are the core boxes?

a) Used to support cores

b) Used to create cores

c) Used to store cores

d) Used to Eject cores while ejection of casting after solidification

Answer: b

Explanation: Core boxes are those elements or tools which are used to create cores.

3. In the case of coldbox core _____________

a) The core mix is heat treated in order to cure it

b) Core mix immediately gets cured after sand is blown

c) Time is given to the core mix to be cure

d) Cold water is poured onto the core mix

Answer: c

Explanation: Due to high production rates, the coldbox are left alone to cure by itself after the sand is blown into the corebox.

4. In the case of shell, hotbox or warmbox ______________

a) Hot water is poured onto the sand mixture

b) The sand mixture is heated to set the core

c) Steam is provided to the core mix

d) The corebox is left in the room temperature

Answer: b

Explanation: The sand mixture needs to be heated in order to set the core. Once, it is set the core is removed from the corebox.

5. What will happen if the parting line in the corebox is not closed properly?

a) Coresand may blow out of the box to create fins on the cores

b) The cope and drag part clamped will detach and break the core

c) Air inclusion occurs as the atmospheric air involves the solidification of core

d) Nothing will happen, as the parting line has no role in core making

Answer: a

Explanation: Obviously, the sand will overflow out causing unwanted contours called fins, which may increase the cost of machining to remove them and time is consumed.

6. Why the air already present inside the corebox is necessary to be evacuated before pressurised air is blown into it?

a) The air has comparatively low pressure hence, distortion occurs

b) Hot tears will occur on the surface

c) It will cause poor sand distribution and poor compaction

d) Nothing will happen as the pressure of incoming air neutralises inside air pressure

Answer: c

Explanation: The air inside the corebox does not get enough time to escape hence sand distribution and compaction is poor.

7. Why should the finishing of the core be made good enough?

a) The intricate shapes made are difficult for machine finishing

b) The size of the cavities and contours must be accurate to enable perfect assemblies

c) It reduces machining cost and time invested for that

d) All of the mentioned

Answer: d

Explanation: The cores are used where machining cost or time is the foundation or is difficult to achieve and hence finishing is done on the core itself.

8. Match the elements in box ‘A’ to their respective functions in box ‘B’ and tick the correct option.

A B

1 – CORE a – ARE USED TO PRODUCE CORES

2 – CORE PRINT b – ARE USED TO PROVIDE SUPPORT TO CORES

3 – CORE BOX c – ARE USED TO MAKE HOLLOW CAVITIES OR HOLES

a) 1-a, 2-b, 3-c

b) 1-b, 2-a, 3-c

c) 1-c, 2-b, 3-a

d) 1-c, 2-a, 3-b

Answer: c

Explanation: The following table shows correct matches.

CORE – ARE USED TO MAKE HOLLOW CAVITIES OR HOLES

CORE PRINT – ARE USED TO PROVIDE SUPPORT TO CORES

CORE BOX – ARE USED TO PRODUCE CORES

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on ” Types of Cores”.

1. Which of the following core cannot be classified by the nature of core material employed?

a) Dry sand core

b) Shell core

c) Sodium silicate core

d) Oil bonded core

Answer: a

Explanation: Dry sand core is a core which comes under state or condition of core, while all other types of cores come under nature of core materials employed.

2. Which of the following will not be classified under the type of core hardening process employed?

a) Nishiyama process

b) Ram up core

c) Furan no-bake system

d) Cold set process

Answer: b

Explanation: Ram up core cannot be classified under the type of core hardening process employed, while the remaining can be classified under it.

3. Which of the following core cannot be classified under the shape and position of the core?

a) Balanced core

b) Ram up core

c) Shell core

d) Horizontal core

Answer: c

Explanation: Among the following, shell core is the core which cannot be classified under shape and position of the core, while the remaining others can be classified under it.

4. Which of the following cores are produced by mixing silica?

a) Green sand cores

b) Dry sand cores

c) Oil bonded cores

d) Resin bonded cores

Answer: c

Explanation: Oil bonded cores are produced by adding silica and a small amount of linseed oil, and then polymerized.

5. In resin bond cores, the core is baked at what temperature?

a) 275°F – 390°F

b) 375°F – 450°F

c) 485°F – 645°F

d) 775°F – 880°F

Answer: b

Explanation: For such types of operations, the core is known to be backed at a good amount of temperature. In resin bond cures, the core is baked in the core box at a temperature range of 375°F – 450°F.

6. In hot box process, core box is heated up to what temperature?

a) 220°F – 300°F

b) 250°F – 320°F

c) 350°F – 500°F

d) 420°F – 550°F

Answer: c

Explanation: In the hot box process, core box is known to be made up of cast irons or steels or aluminium metal. It is heated in between the temperature range of 350°F – 500°F.

7. Sodium silicate reacts with carbon dioxide to give what?

a) Sodium dichromate

b) Sodium sulphide

c) Sodium bicarbonate

d) Sodium carbonate

Answer: d

Explanation: When sodium silicate is made to react with carbon dioxide gas, it is known to yield sodium carbonate and silica gel.

8. Silica gel is formed when sodium bicarbonate reacts with carbon monoxide.

a) True

b) False

Answer: b

Explanation: Silica gel is formed along with sodium carbonate when sodium silicate reacts with carbon dioxide.

9. What percentage of clay content is required in furan-no-bake system?

a) Less than 0.3%

b) Less than 0.4%

c) Less than 0.5%

d) Less than 0.6%

Answer: c

Explanation: In furan-no-bake system, there is very less amount of clay content present in it. The cores and mixture are found to contain less than 0.5% of clay.

10. What percentage of powered ferrosilicon is mixed with sodium silicate bonded sand in Nishiyama process?

a) 1%

b) 2%

c) 3%

d) 4%

Answer: b

Explanation: In Nishiyama process, 2% of finely powered ferrosilicon is made to mix with sodium silicon bonded sand to ensure that hardening occurs.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Dielectric Core Bakers”.

1. In dielectric core baker, several metallic plates are used for supporting the cores in the system.

a) True

b) False

Answer: b

Explanation: Dielectric core bakers are basically based on dielectric heating. The core supporting metallic plates cannot be used in this type of baker because they interrupt the potential distribution in the electrostatic field. To avoid this interruption or interference, cement bonded asbestos plates can be used for supporting the cores instead of metallic plates.

2. Dielectric core bakers are faster in operation and have good control of maintaining the temperature.

a) True

b) False

Answer: a

Explanation: The main advantage of dielectric core baker is that they are very faster in operation and have good control of maintaining the temperature. After baking of cores in dielectric baker, they are further smoothened by using dextrin material, sometimes water soluble binders are also used for this purpose.

3. For small cores mass production, dielectric core bakers can be preferred over continuous type ovens used for baking cores.

a) True

b) False

Answer: b

Explanation: Dielectric core bakers are faster in operating the system but cannot be preferred over continuous type ovens for small cores mass production. Continuous type ovens are mainly preferred for mass production. In this baking system, core carrying conveyors are used which continuously moves through the oven.

4. After baking of cores in dielectric core bakers, they can be directly used in the moulding box.

a) True

b) False

Answer: b

Explanation: After baking of cores in dielectric core bakers, finishing operation is a must before they set in the moulding box. Finishing is the last process which completes the formation of a core. This is a process in which bumps or other sand projections are removed from the surfaces of cores by filing them in a fixture.

5. Core finishing also includes a coating of refractory materials on cores to protect them.

a) True

b) False

Answer: a

Explanation: Cores are generally coated with refractory or protective materials by performing several operations like brushing, dipping and spraying, which greatly improves the refractoriness and surface finish of the cores. The coating material on cores also restricts the liquid metal from entering into the pores of a core.

6. It is not possible to bake dry sand cores by dielectric core bakers.

a) True

b) False

Answer: b

Explanation: Dry sand cores are basically produced by heating the green sand cores nearly about 110 ⁰C. These cores have high strength rigidity and excellent thermal stability. These cores can be easily baked by dielectric core bakers and normally stored for a long period of time to make them more stable than the green sand cores. Dry sand cores generally used for large castings production.

7. How much percentage of water or moisture is contained by green sand cores?

a) 5%

b) 10%

c) 20%

d) 40%

Answer: a

Explanation: Green sand cores are made of green sand which mainly contains water or moisture nearly about 5% and 15 to 30 % of clay. It imparts very high permeability to the core material and hence reduces the chance of defects such as shrinkage or voids in the casted parts. Green sand cores are not dried but usually baked by dielectric bakers to maintain the moist content.

8. In dielectric core baker system, a metal used generally requires a low value of K 

a) True

b) False

Answer: b

Explanation: In dielectric core baker systems, a dielectric material is used that should have a high value of K , which basically provides the required electrical properties to operate the system efficiently. More the value of K, then more will be the effect of baker system on the baking cores.

9. The process of making green sand cores generally consumes much time as compared to that of dry sand cores.

a) True

b) False

Answer: b

Explanation: Green sand cores are generally preferred for simple, small and medium castings. The process of making green sand cores do not consume much of time. The process is accomplished quickly that causes less strength in green sand cores as compared to that of dry sand cores. Dry sand cores usually take longer time in making of themselves.

10. In dielectric baker systems, cement plates are normally used for supporting the cores.

a) True

b) False

Answer: a

Explanation: In dielectric baker systems, the heating of core is done by placing them in the electrostatic field. The dielectric material generates heat in the system that is directly supplied to the cores. In this system, there should be no interruption of any metallic material, so cement plates are widely used instead of metallic plates in the baking system for supporting the cores.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Setting The Cores”.

1. The following figure represents which type of chaplet?

casting-questions-answers-setting-cores-q1

a) Radiator chaplet

b) Stem chaplet

c) Cast chaplet

d) Sheet metal chaplet

Answer: a

Explanation: The following figure represents a radiator chaplet. This particular chaplet holds a very important duty, wherein it helps the cores by supporting them.

2. Name the material in place of the question mark?

casting-questions-answers-setting-cores-q2

a) Mold cavity

b) Core seat

c) Chaplet

d) Molding sand

Answer: a

Explanation: The material in place of the question mark is a mold cavity. Inside this mold cavity, there some place into which, while operating, the mold is kept.

3. Name the material in place of the question mark?

casting-questions-answers-setting-cores-q3

a) Mold cavity

b) Core seat

c) Chaplet

d) Molding sand

Answer: b

Explanation: The apparatus in place of the question mark is a core seat. The core seat plays a vital role in this operation. It helps in holding the core firmly.

4. Name the material in place of the question mark?

casting-questions-answers-setting-cores-q4

a) Mold cavity

b) Core seat

c) Chaplet

d) Molding sand

Answer: c

Explanation: In the place of the question mark, it is a chaplet, which are positioned in between mold and core surfaces.

5. Name the material in place of the question mark?

casting-questions-answers-setting-cores-q5

a) Mold cavity

b) Core seat

c) Chaplet

d) Molding sand

Answer: d

Explanation: The material which is in the place of the question mark is molding sand. The molding sand is an important component as, on this the entire apparatus is kept.

6. Which force is experienced by cores in the mold?

a) Shear force

b) Magnetic force

c) Buoyant force

d) Electric field force

Answer: c

Explanation: The force experienced by the cores inside the molds is a buoyant force, which is the upward force exerted by a fluid. This force is available due to poured molten metal.

7. How many core prints are required to locate a core?

a) One

b) Two

c) Three

d) Four

Answer: c

Explanation: Core prints or core seats are used for the location of a core. For this, an amount of three core prints or core seats are enough to properly locate a core.

8. What is positioned between mold and core surface?

a) Chaplets

b) Molding surface

c) Core seat

d) Mold cavity

Answer: a

Explanation: Chaplets are a type of metal shape which are positioned between mold and core surface. These chaplets first melt and then they become a part of the castings.

9. When does chaplet become a part of casting?

a) After molding sand is poured

b) After molding cavity is introduced

c) After molten metal is poured

d) After core prints provide the pattern

Answer: c

Explanation: Chaplet becomes a part of casting by melting. Chaplet melts and becomes a part of it. Chaplets are a type of metal shape which are positioned between mold and core surface.

10. Big cores are set in molds by hand.

a) True

b) False

Answer: b

Explanation: Big cores are set up quite easily with the help of cranes, whereas when small cores are to be set up, they are set in molds using a hand.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Core Application”.

1. Cores are generally made of relatively low strength for better utilization in the production of castings.

a) True

b) False

Answer: a

Explanation: In general, cores are made of two types which are green sand cores and dry sand cores, and both types of cores are made of relatively low strength than that of mould. This is basically done for easy removal of cores after solidification of castings so that the cores are easily break off and removed from the casting part.

2. Dry sand cores are widely used in the injection moulding process for casting various polymers.

a) True

b) False

Answer: b

Explanation: In the injection moulding process, alloy cores are used in the moulding box instead of any sand cores. In the process, the plastic is getting injected into the moulding box and then after solidification, the casted polymer is taken out from the moulding box with the cores still in it. And then the core is melted and washed out from the moulding box.

3. Green sand cores are not suitable for producing very complex shapes of castings.

a) True

b) False

Answer: a

Explanation: In the production of very complex shapes of castings, green sand cores are not compatible as they are made of low strength and cannot bear forces for a long period of time. So generally, dry sand cores are commonly used for producing complex shapes of castings instead of green sand cores.

4. Core prints are generally provided on the mould for easy removal of cores from the moulding box.

a) True

b) False

Answer: b

Explanation: The core prints are mainly provided on the mould so that the cores are securely positioned in the mould cavity. The design of the core print is made in such a way to take care of the weight of the core while pouring of molten metal; it also ensures that the core is not shifted during the entry of molten metal into the mould cavity.

5. It is not necessary for the chaplets to be of the same material as the material being casted in the mould.

a) True

b) False

Answer: b

Explanation: In the moulding box, chaplets are mainly used for supporting the cores. Chaplets are more utilized when the long cores are used with the production of complex castings. It is very important and necessary for the chaplets to be of the same material as the metal being casted because the chaplets get melted and become the part of the casting during the pouring operation.

6. Optimized design of chaplets is very necessary for the application of chaplets in supporting the cores.

a) True

b) False

Answer: a

Explanation: Chaplets design should be optimized because if they are too small they will melt completely and will make the core to move, but if they are too big then their whole part will not melt and fuse with the poured molten metal. So, use of chaplets must also be minimized because they may cause defects or produce a weak point in the casting components.

7. For the removal of cores from the moulding box, caustic bath can be used which is very fast in processing the large and complex cores.

a) True

b) False

Answer: b

Explanation: For the removal of cores from the moulding box, several methods can be used. But for low cost and minimizing the casting erosion, a caustic bath is used which is also known as mechanical agitation. In this method, a solution of sodium or potassium hydroxide is used for the breaking of a core material. But this method consumes too much time for processing the large and complex cores.

8. For removing cores from the castings, the hydraulic cleaning method is much safer than the method of caustic bath.

a) True

b) False

Answer: a

Explanation: In the caustic bath or mechanical agitation, some chemicals are used which are generally associated with the high level of health, safety and environmental risks. So to avoid such types of risks and to perform safer, hydraulic cleaning method is used in which a high pressure water jet is used which erodes the core particles from the casting part.

9. Core dryers are basically the flat surfaces used for supporting the cores in the moulding box.

a) True

b) False

Answer: a

Explanation: In the moulding box, the cores should be prevented from sagging and breaking. So for supporting the cores, flat surfaces are required which are commonly called as core dryers. Core dryers can be made as metal castings with thin sections in order to absorb minimum heat. For large production of castings, many core dryers are required. Core dryer is shown in the below figure-

casting-questions-answers-core-application-q9

10. Core wires and rods can be used for removing the core mass from the casting part.

a) True

b) False

Answer: b

Explanation: Core wires and rods are meant for small or slender cores which do not have sufficient strength to bear the load and pressure of molten metal during the pouring operation. So these types of cores are supported by embedding the wires and rods into the core parts which are called as core wires.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Types of Molds”.

1. Which of the following is not counted as mold characteristics?

a) Possession of strength

b) Possession of refractoriness

c) Resist corrosion

d) Resist metal penetration in molds

Answer: c

Explanation: Resisting corrosion is not any of the characteristics of molds while remaining others are counted as mold characteristics.

2. Which of the following sand mold contains free water?

a) Green sand mold

b) Dry sand mold

c) Core sand mold

d) Shell mold

Answer: a

Explanation: Among the following, green sand mold is found to contain free water. Since it is known to contain some amount of free water, there is some dampness seen in it.

3. Green sand is heated to what temperature to convert it into dry sand?

a) 150°F – 300°F

b) 200°F – 450°F

c) 250°F – 550°F

d) 300°F – 650°F

Answer: d

Explanation: To convert green sand into dry sand, the green sands are heated to a fairly good amount of temperature. This temperature would range in between the ranges of 300°F to 650°F.

4. A skin dried mold is dried up to what depth?

a) 4mm – 12mm

b) 5mm – 19mm

c) 6mm – 25mm

d) 7mm – 23mm

Answer: c

Explanation: A skin dried mold, is dried only up to a depth from 6mm to 25mm. These molds are specifically dried only up to this depth, with an intention that, the mold may possess strength.

5. In cement bonded sand mold, sand mold material consists of what percentage of silica sand?

a) 75.5%

b) 80.5%

c) 85.5%

d) 90.5%

Answer: c

Explanation: In a cement bonded sand mold, it is observed that the sand mold material consists of a very high content of silica sand. Cement bonded sand mold contains 85.5% composition of silica sand.

6. In cement bonded sand mold, sand mold material consists of what percentage of Portland cement?

a) 10%

b) 15%

c) 20%

d) 25%

Answer: a

Explanation: In a cement bonded sand mold, sand mold material consists of 10% composition of Portland cement, whereas it contains 85.5% composition of silica sand.

7. A skin dried mold has to be poured immediately after drying.

a) True

b) False

Answer: a

Explanation: A skin dried mold cannot be made to wait after drying and has to be immediately poured, else, it may catch the moisture from green sand and may become ineffective.

8. In cement bonded sand mold, sand mold material consists of what percentage of water?

a) 3.5%

b) 4.5%

c) 5.5%

d) 6.5%

Answer: b

Explanation: None.

9. For how long is the mold in cement bonded sand mold, allowed to set?

a) 24 hours

b) 48 hours

c) 72 hours

d) 96 hours

Answer: c

Explanation: The mold in cement bonded sand is allowed to get set, get dry and get cured for about 72 hours before pouring.

10. Green sand mold contains high strength.

a) True

b) False

Answer: b

Explanation: Green sand mold is found to contain a very low amount of strength and a low amount of permeability.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Molding Processes”.

1. Which of the following is the principal material used for Nobake moulding process?

a) Furan or Urethane

b) Wood saw

c) Clay-bentonite

d) Water only

Answer: a

Explanation: Nobake is a moulding process that involves the use of furan  to bond the moulding sand.

2. In Nobake moulding process, the chemical process of hardening of binder starts when ___________

a) The sand is poured into the mixture

b) The sand is taken out of the mixture

c) The mixture is poured into the moulding flask

d) When the molten metal is poured into the cavity

Answer: b

Explanation: A mixture is used to blend the sand with chemical binder. The chemical hardening starts when this sand exits the mixture.

3. The Nobake mould have a higher strength as compared to other moulds due to _________

a) Its higher moisture content

b) Its lower moisture content

c) The property to withstand higher metallostatic pressures during casting

d) The property to adapt to any volume

Answer: c

Explanation: The Nobake moulding process provides a good strength of mould, hence, it can withstand the metallostatic pressures and can give good dimensional tolerances.

4. Which of the following statement is true?

a) It is possible to pour only ferrous metals for casting in Nobake process

b) It is possible to pour only non-ferrous metals for casting in Nobake process

c) Both ferrous as well as non ferrous metals can be used for casting through Nobake process

d) Neither ferrous, nor non-ferrous metals are used for casting in nobake process

Answer: c

Explanation: Both ferrous as well as non-ferrous metals are compatible with mould made though Nobake process.

5. The degree or intensity of ramming _________

a) Increases bulk density

b) Decreases bulk density

c) Does not change bulk density

d) Can increase as well as decrease bulk density

Answer: a

Explanation: The increased degree of ramming results in an increase of bulk density or hardness of sand.

6. Permeability of green sand ________

a) Increases with ramming

b) Decreases with ramming

c) Can increase and decrease as well with the amount of ramming

d) Does not alter with ramming

Answer: b

Explanation: The permeability of green sand decreases with an intensity of ramming done on the sand. Hence, the amount of clay is adjusted to keep permeability in a profitable zone.

7. Natural moulding sand have which of the following quality __________

a) Freely available in abundance

b) Contains clay in a large amount

c) Moisture content range is wider

d) All of the mentioned

Answer: d

Explanation: Natural moulding sand is cheap, easily available and has a proper consistency of moisture and clay. Hence, requires less time for preparation.

8. R.P.M stands for which of the following moulding process?

a) Rotor Plastic Moulding

b) Raisin Pit Moulding

c) Rubber Plaster Moulding

d) Rough Print Moulding

Answer: c

Explanation: R.P.M stands for Rubber Plaster Moulding. RPM is also known as plaster moulding, since, use of plaster of paris is done in this process.

9. RPM is only used for castings of which of the following material?

a) Ferrous metals

b) Non-ferrous Metals

c) Plastics

d) Silicone

Answer: b

Explanation: Rubber Plaster Moulding process is used for making mould that can only be used for producing non-ferrous castings like copper and aluminum based alloys.

10. What is the range of temperature used for baking molds using plaster moulding process?

a) 50°-100°

b) 80°-120°

c) 120°-260°

d) 250°-300°

Answer: c

Explanation: The preset mould is ignited to burn off the volatile content in the set gel to a temperature range of 120°-260°.

11. The baking process in plaster moulding process induces which of the following defects?

a) It depletes down the content of water at a very scarce level

b) It develops microscopic cracks onto the surface of mould

c) It gives the surface improper heat that causes differential heat treatment while casting solidification

d) The Calcium reacts at elevated temperatures used for baking the mould

Answer: b

Explanation: The baking of mould in plaster moulding process causes the development of microscopic cracks, which results in improper surface of casting.

12. The dried plaster mould have __________

a) Low permeability

b) High permeability

c) Moderate permeability

d) Same amount of permeability as other moulds

Answer: a

Explanation: The dried plaster moulds have extremely low permeability, about- 1 to 2 AFS.

13. Pit moulding is used for _________

a) Low weighting castings

b) Moderate weighting castings

c) Heavy weighting castings

d) Making castings that requires less time to process

Answer: c

Explanation: Very heavy castings can be made out using pit moulding process. Castings weighing up to 150 tons can be processed through pit moulding.

14. Which of the following is a principle binder used in carbon dioxide moulding?

a) Carbon

b) Carbon Dioxide

c) Sodium

d) Sodium silicate

Answer: d

Explanation: Sodium silicate is the principle binder used in carbon dioxide moulding process. The mixture of sodium silicate and sand is treated with carbon dioxide to form a bond.

15. Which of the following compound forms the bond between sand particles in carbon dioxide moulding process.

a) Sodium

b) Amorphous silica

c) Dehydrated water

d) Carbon Monoxide

Answer: b

Explanation: Amorphous silica forms the bond between sand particles. It is produced by reaction or treatment of the mixture of sand and sodium silicates by carbon dioxide.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Methods of Ramming Mold Boxes – 1”.

1. What is the disadvantage of hand molding?

a) Damage to the projections

b) Costly method

c) Non-uniform strength

d) Poor surface finish of the mold

Answer: c

Explanation: In hand molding, the ramming force required for compressing the molding sand is applied by human hand. A human knows about projection in the pattern accordingly he applies force thus no damage to projections. Surface finish obtained is also good. But, the force applied is non-uniform which results in non-uniform strength.

2. Which is not a machine molding process?

a) Jolting

b) Squeezing

c) Sand slinging

d) Hand molding

Answer: d

Explanation: In jolting, a sand-filled mold is raised to a certain height and allowed to fall freely onto the ground converting potential energy into impact energy which leads to ramming of sand. In squeezing, a press is used to apply pressure through a plate. In the sand slinging, small-small amount of sand will be thrown that leads to localized ramming of sand. Hand molding is done without machines.

3. Which machine molding process will give uniform strength throughout the mold?

a) Sand slinging

b) Squeezing

c) Jolt and squeezing

d) Jolting

Answer: a

Explanation: In sand slinging, we will obtain uniform strength throughout the mold because localized ramming of sand takes place because of throwing the small-small amount of sand into the mold box at the same amount of force. But in other processes strength will be more at the top or bottom or middle.

4. In which of the following molding process strength at the top of the mold is higher?

a) Hand molding

b) Squeezing

c) Jolting

d) Jolt and Squeezing

Answer: b

Explanation: In squeezing, we apply force with the help of a ram. Due to applied pressure ramming of sand takes place but the same load is not able to transmit to the bottom of the mold resulting in lower strength at the bottom portion of the mold. But, in jolting impact force act at the bottom. In jolt and squeezing, uniform strength will be achieved. In hand molding, strength will be non-uniform.

5. In which of the following molding process strength at top of the mold is less?

a) Hand molding

b) Squeezing

c) Jolting

d) Jolt and Squeezing

Answer: c

Explanation: During jolting, the sand-filled mold is taken to a certain height so that it possesses potential energy and then allowed to fall freely onto the ground. Due to impact force transmitted to the bottom of the mold is very high when compared to the top of the mold that leads to high strength at the bottom and low strength at top of the mold.

6. Which of the following molding methods is the most costly?

a) Sand slinging

b) Jolt and squeezing

c) Jolting

d) Hand molding

Answer: a

Explanation: Sand slinging machine is costly, also involves more cycle time and thus results in higher power consumption. Thus the cost involved is more. In jolting and jolt with squeezing machine cost is less with less cycle time, and in hand molding, no machine is used thus less costly than sand slinging.

7. Which of the following molding methods have the least production rate?

a) Squeezing

b) Jolt and squeezing

c) Jolting

d) Hand molding

Answer: d

Explanation: In hand molding operation the force required for ramming the mold is applied by human hand thus the time taken for making the mold is longer. This leads to the least production rate when compared with the above processes. Whereas in other methods machines are used reducing the production time.

8. Which of the following molding methods have the highest production rate?

a) Squeezing

b) Jolt and squeezing

c) Jolting

d) Sand slinging

Answer: c

Explanation: In jolting, we only need to take the mold to a certain height and then drop it. Thus highest production rate of the is achieved. Sand slinging requires more time as it is a repetitive process. Jolt and squeezing combines both jolting and squeezing hence will take more time than jolting. In squeezing, we need to keep the force for a certain time which reduces the production rate.

9. Jolt and squeezing can be used for achieving uniform strength if the height of the mold is up to 200 mm.

a) True

b) False

Answer: a

Explanation: Jolt and squeezing is a combination of jolting and squeezing. First of all jolting is done followed by squeezing. If the height of mold is less than 200 mm, throughout the depth of mold uniform strength is achieved. If the height of mold is more than 200 mm, the force will not transmit to the middle portion of mold hence, less strength at center.

10. In the sand slinging process we can’t use a pattern with extension or projection.

a) True

b) False

Answer: a

Explanation: During sand slinging, sand is thrown with a higher amount of force into the mold box and will hit the projection present on the pattern. This will result in the damage of the pattern. Thus, the sand slinging operation is used only for a simple pattern without any projection or extension.

This set of Tricky Casting Questions and Answers focuses on “Methods of Ramming Mold Boxes – 2”.

1. Which of the following methods of ramming is suitable for the small batch production of castings?

a) Hand moulding

b) Squeezing

c) Jolting

d) Sand slinging

Answer: a

Explanation: For the small batch production, it is very convenient to use the hand moulding method of ramming which is done manually and rest of the methods are mainly performed by the machines. So, it is very economical and time saving to use hand moulding for the small level production of castings.

2. Which of the following parts is used in jolt moulding to ram the sand in mould?

a) Biscuit

b) Jolt

c) Roller

d) Overhead hopper

Answer: d

Explanation: Basically, an overhead hopper is used in jolt mould method of ramming, in which after filling the sufficient amount of sand to the mould, an overhead hopper is raised to a certain height and then it is allowed to free fall on to a solid bed plate, which results into the ramming and packing of sand layers in the mould.

3. Jolt method of ramming makes smooth ramming and packing of sand layers in the mould.

a) True

b) False

Answer: b

Explanation: In the method of jolt moulding, it gives rise to uneven packing and it is very severe on the moulding equipment also. The sand at the bottom experiences the highest force and the magnitude of the force is decreases in upward direction, so the bottom layers packed well as compared to the top layers in the mould.

4. The jolt method of ramming can be suitable for horizontal surfaces in the mould.

a) True

b) False

Answer: a

Explanation: In the jolt method of ramming, impact force is generated by the application of overhead hopper, this impact force compact the sand uniformly in the mould. This is achieved by continuous lifting and dropping of hopper and then the required hardness is achieved by the mould. Horizontal surfaces are mostly compatible or preferred for the optimization of this method.

5. The method of jolt ramming operates very leniently with the moulding equipment.

a) True

b) False

Answer: b

Explanation: The method of jolt ramming is very severe on the moulding equipment because the lifting and dropping operations can affect the mould layers due to the impact forces, which abruptly disturb the mould material by the high magnitude of force, this can even lead to cracking and breaking of mould.

6. The problem with moulding equipment in jolt moulding can be avoided by implementing a squeeze method of ramming.

a) True

b) False

Answer: a

Explanation: In squeeze ramming, a plate smaller than the inside dimensions of the moulding flask is fitted with the moulding sand. Then a uniform pressure is applied by the downward movement of a plate or by the upward movement of the flask itself, so this method avoids the damage to the moulding equipment.

7. In squeeze ramming, hardness achieved is inversely proportional to the pressure applied on the squeeze plate.

a) True

b) False

Answer: b

Explanation: In squeezing method of ramming, the resulting force compact the sand uniformly and the hardness achieved directly depends to the pressure applied on the plate. More the pressure more will be the hardness of the sand, but the sand next to the plate rams hardest while the sand below is progressively less hard.

8. In squeeze ramming, plate is always provided with a contour to achieve a better hardness of the sand.

a) True

b) False

Answer: a

Explanation: Generally, the hardness achieved follows the contour of the squeeze plate which is in contact with the sand, Contour is always provided with the plate to match the pattern to achieve a better uniform hardness of the mould. So, application of contour is very essential for better and efficient ramming.

9. Squeeze ramming is best for big castings and mainly suitable for high depth flasks.

a) True

b) False

Answer: b

Explanation: Squeeze ramming is suitable for small castings and is generally suitable for shallow flasks which are of little depth. In this method of ramming, it is also possible to use a diaphragm to provide differential ramming force which is generally required for the contour of the pattern.

10. Which of the following is the best method for the uniform ramming of moulding sand?

a) Jolting

b) Squeezing

c) Sand slinging

d) Hand moulding

Answer: c

Explanation: Sand slinging is defined as the combination of jolt and squeeze method of ramming, in which jolt-squeeze machines are used for the more uniform ramming. This is the method which is widely used in the ramming process, but the processes are expensive due to the application of various machines.

11. Sand slinging method is best, but the process takes too much time to accomplish the operation.

a) True

b) False

Answer: b

Explanation: Sand slinging is a very fast method of ramming, it is done by throwing sand into the flask rapidly with the great force. This process develops uniformly high mould hardness. Sand slinging is the best method comparatively, but the cost of equipment used in this method is very high as compared to the other methods of ramming.

12. In sand slinging, which of the following parts is used for the spraying of moulding sand into the flask?

a) Biscuit

b) Runner

c) Diffuser

d) Nozzle

Answer: d

Explanation: In the sand slinging method of ramming, the sand is uniformly sprayed into the mould by moving the nozzle through the entire area of the flask. Also, it is necessary that the sand is sprayed in layers to achieve uniform hardness. This method is very economical and widely used for ramming.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Methods Of Green Sand Molding”.

1. Which of the following is the simplest sand molding?

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: a

Explanation: Among the following, open sand method molding is the easiest and simplest of the three green sand molding methods.

2. Which of the following is not an application of Open sand molding method?

a) Grills

b) Floor plates

c) Weights

d) Cupboards

Answer: d

Explanation: Among the listed applications of an open sand molding method, making cupboards is not an application of it.

3. Which method is used if the upper surface of casting is required to be smooth?

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: b

Explanation: If the requirement of the casting is that, its upper surface should be smooth, bedded in the method should be used.

4. In bedded-in method, what shape does the upper surface of the casting have?

a) Round

b) Helical

c) Flat

d) Trapezoidal

Answer: c

Explanation: In the bedded-in molding method, the upper surface of the casting, which has to be smoothened, can be any other shape, but not flat.

5. Railing and gates is an application of which of the following molding method?

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: a

Explanation: Castings which are simple with tops being flat, can be produced from the open sand molding method.

6. Which of the following method can be used for both solid patterns and split patterns?

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: c

Explanation: For both the patterns to be produced, that is solid and split patterns, turn-over method of molding can be used.

7. The following figure represents which molding method?

casting-questions-answers-methods-green-sand-molding-q7

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: c

Explanation: The following figure represents a turn-over method of molding, where the drag flask is kept over the pattern.

8. How much is the floor sand in a typical dry sand molding mixture?

a) 30%

b) 35%

c) 40%

d) 45%

Answer: c

Explanation: In a typical dry sand molding mixture, the total content of floor sand is approximately about 40%, for making non-ferrous castings.

9. Which of the following imparts a better dimensional accuracy?

a) Open sand method molding

b) Bedded-in method molding

c) Turn-over method molding

d) Dry sand molding

Answer: d

Explanation: Among the four methods of molding mentioned here, dry sand molding offers better accuracy in dimensions than the green sand molding types mentioned.

10. Dry sand molding is cheaper as compared to green sand molding.

a) True

b) False

Answer: b

Explanation: Dry sand molding, as compared to green sand molding is a bit expensive process, as it involves more time as well as labour.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Hand Molding Equipment”.

1. Which of the following is not a hand molding process?

a) Air cooling

b) Ramming

c) Placing

d) Turning over

Answer: a

Explanation: Among the following processes, air cooling is not a type of hand molding process, while the remaining other processes are hand molding processes.

2. How apart should gaggers be located?

a) 65mm

b) 70mm

c) 75mm

d) 80mm

Answer: c

Explanation: A gagger is made up of steel reinforced bar. These gaggers should be located at a distance of 75mm from each other.

3. At what distance should the gagger be kept from the pattern?

a) 3mm

b) 6mm

c) 9mm

d) 12mm

Answer: b

Explanation: The distance between a gagger and a pattern should be about 6mm so that it is within the reach of the pattern.

4. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q4

a) Bellow

b) Sprue pin

c) Spirit level

d) Swab

Answer: b

Explanation: The hand molding equipment here is a sprue pin. A tapering is provided to the pin, that is, the diameter of the pin keeps increasing from one end to another.

5. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q5

a) Pipe smoother

b) Button smoother

c) Spirit level

d) Swab

Answer: b

Explanation: The hand molding equipment which is shown in the figure is a button smoother. They ensure the repairing work of the casts. Not just that, they also help in the finishing work.

6. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q6

a) Gagger

b) Draw spike

c) Peen rammer

d) Swab

Answer: b

Explanation: The hand molding equipment which is shown in the figure is a draw spike. It is a sharp tapered rod, that is, the diameter of the rod goes on increasing from the tip till the end.

7. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q7

a) Gate cutter

b) Draw spike

c) Swab

d) Hand riddle

Answer: a

Explanation: In the given figure of the hand molding equipment which is shown is a gate cutter. A gate cutter is basically a sheet metal which is given a definite shape, so as to be able to perform proper cutting operations.

8. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q8

a) Trowel

b) Vent wire

c) Spirit level

d) Swab

Answer: a

Explanation: The hand molding equipment which is shown in the figure is a trowel. It is used for flat finish of the mold surface. These are basically used for cutting ingates.

9. The following figure represents which hand molding equipment?

casting-questions-answers-hand-molding-equipment-q9

a) Trowel

b) Vent wire

c) Spirit level

d) Swab

Answer: b

Explanation: The hand molding equipment here is a vent wire. It has a spiked tool and a handle at the back. It is mainly used for making holes in sand.

10. Hand rammer is made up of metal.

a) True

b) False

Answer: a

Explanation: Hand rammers are used for ramming sand in bench mold. It can be made up of either metal or it could be of wood too. The material depends on the type of operation.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Steps Involved In Making a Mold”.

1. Which of the following processes is the first step involved in the sand casting?

a) Clamping

b) Cooling

c) Mould making

d) Pouring

Answer: c

Explanation: The first step involved in the sand casting method is to produce the mould for the casting. In an expendable moulding process, this step should be done for each different casting. A sand mould is basically produced by packing sand mass into each half of the mould. The sand mass is rammed near at the pattern side; pattern is a replica of the casting to be made.

2. It is possible to provide any kind of internal features to the casting by the help of pattern.

a) True

b) False

Answer: b

Explanation: It is not always possible to use pattern for generating internal features to the casting. Any kind of internal features of the casting which cannot be produced by the application of pattern are produced by using the separate cores which are mostly formed by the sand that can be green sand or dry sand, depending on the purpose.

3. In mould making process, moulding time is greatly affected by the shape and size of the casting components.

a) True

b) False

Answer: a

Explanation: In mould making process, the moulding time generally involves positioning of pattern, sand ramming and pattern extraction from the moulding box. The mould making time is greatly affected by the size and shape of the casting components, number of cores, and the type of sand mould used in the process.

4. In mould making process, clamping is basically done to prevent any loss of material from the moulding box.

a) True

b) False

Answer: a

Explanation: In mould making process, after placing of cores in the mould, the mould parts are closed and clamped together by a clamping operation. It is very essential that the mould parts remain closely clamped together to prevent any loss of molten metal. Clamping is a very important operation and must be performed with great care.

5. It is not possible to estimate solidification time by considering the wall thickness and temperature of the casting metal.

a) True

b) False

Answer: b

Explanation: When the mould cavity is filled with molten metal and during its solidification, the final shape of the casting part is formed. The mould cannot be opened until the cooling time has elapsed. The desired cooling or solidification time can be estimated by considering the wall thickness and the temperature of the casting metal.

6. During the pouring process, filling time of molten metal should be short to avoid early solidification of the casting.

a) True

b) False

Answer: a

Explanation: During pouring operation, the molten metal is poured into the mould by the application of ladle. The filling time of molten metal should be kept short in order to avoid early solidification of any part of the casting component. The filling of melt through the ladle can be performed manually or by an automated machine.

7. The process shakeout is generally referred to escaping of gases from the molten casting during the solidification.

a) True

b) False

Answer: b

Explanation: After the solidification of the casting component, the sand mould is broken and the casting part is extracted from the broken mould. This process is also known as shakeout and it is commonly performed by a vibrating machine or tool that shakes the sand particles and then the casting comes out from the flask.

8. Quick solidification of the casting can cause defects like shrinkages, cracks or blow holes.

a) True

b) False

Answer: a

Explanation: The molten metal is poured into the mould cavity that begins to cool and solidify. During solidification, most of the defects which may occur are a result of the solidification process. If the molten metal solidifies too quickly, then the casting parts may exhibit defects like shrinkage, cracks or blow holes.

9. Shot blasting operation is mainly done to identify the type of defects in the casting part.

a) True

b) False

Answer: b

Explanation: After removing of casting part from the mould, the casting part is likely to have some sand particles and oxide layers which adhered to the surface. Shot blasting is an operation which is mainly performed to remove any remaining sand particles, especially from internal surfaces. This process also reduces the surface roughness of the casting part.

10. A trimming press is a machine tool which is widely used for removing the excess material from the casting part.

a) True

b) False

Answer: a

Explanation: During solidification, the material from the channels in the mould solidifies and joined to the casting part. This excess material should be trimmed from the casting part, for which a trimming press is used that removes excess material very finely. The time needed for trimming the excess material can be estimated from the size of the casting’s envelope.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Venting of Moulds”.

1. Venting is a process which allows molten metal to compensate for its liquid and solidification shrinkage.

a) True

b) False

Answer: b

Explanation: The compensation for liquid and solidification shrinkage of the molten casting is basically done by setting up risers in the casting system. Venting is a process which allows the escaping of gases from the molten metal during the solidification. For the venting process, a vent is provided in the casting system through which gases escape out.

2. Which of the following effects is the effect caused by the ignition of oxygen due to high pressure and temperature of melt?

a) Otto effect

b) Dual effect

c) Diesel effect

d) Rankine effect

Answer: c

Explanation: Proper mould venting is very important and necessary for producing quality casting parts. During the moulding process, the gases included in the mould needs a way to escape, or else the molten metal will compress and trap those gases in the mould cavity. A combination of high melt pressure and temperature will then ignite the oxygen and will cause an effect that is called a diesel effect.

3. Improper venting during moulding process causes a diesel effect which further results in stress crack defects in the casting.

a) True

b) False

Answer: a

Explanation: Improper or poor venting during moulding process causes a diesel effect that mainly occurs due to the combination of melt pressure and high temperature which ignite the oxygen and causes burnings in the mould which is also called as carbonization process that further results in marks and crack defects in the finished casting components.

4. For proper venting, the pouring time is increased which allow easy escape out of gases from the mould without inducing any defects.

a) True

b) False

Answer: b

Explanation: For maintaining the proper venting, the pouring time cannot be increased because that will cause other problems in the casting process such as early solidification which will form the incomplete sections in the casting and several defects in the casting components like cracks and shrinkages.

5. High viscosity of molten metal can help in removing of gases but will cause defects in the casting.

a) True

b) False

Answer: a

Explanation: For keeping the high viscosity of molten metal, the temperature of the melt should be kept low, but greater than its melting point. High viscosity generally reduces the pouring speed which takes more time to complete the process. This may be done for venting but it will cause defects in the casting such as cold cracks, incomplete sections, shrinkages etc.

6. Porous sintered materials can be inserted into the mould cavity to act as a vent.

a) True

b) False

Answer: a

Explanation: Porous sintered materials can be placed in the mould cavity to act as a vent. It mainly depends on the thickness of the porous material used. More the thickness, then less will be the venting capacity. So venting passages should be machined properly to collect the gases, proper cleaning of vents is also important as the gas deposits can block the passages.

7. Vacuum technology for venting process is very economical and widely used in the casting process.

a) True

b) False

Answer: b

Explanation: Vacuum technology for venting process includes removing of gases from the cavity before the pouring of molten metal. This actually generates a vacuum inside the cavity for which the cavity must be sealed completely. And although vacuum technology may solve gases problems, it is not effective in dealing with gas produced during pouring, so this process is not economical and cannot be used conventionally.

8. In the injection moulding process, an overflow system is used for the venting process.

a) True

b) False

Answer: a

Explanation: An overflow system is an area which is connected to the mould cavity through a channel that is mainly created by machining an exit gate that joins the cavity’s last filling point with a cold runner that ends in a venting area. A groove is machined at the vent to collect all the gases and allow them to escape out from the mould.

9. For the venting process, the casting yield is generally high with the overflow system in the mould.

a) True

b) False

Answer: b

Explanation: An overflow system includes extra material or metal which is wasted after every shot, overflow cutting operation and additional space requirements. This decreases the material or casting yield in the production of casting components. This further increase the cost involved in material handling.

10. In the injection moulding process, venting at the runner side can reduce the air pressure.

a) True

b) False

Answer: a

Explanation: Venting at the runner side can decrease the air pressure because the air inside the sprue is ejected instead of compressing it into the mould cavity. Bernoulli’s principle states that an increase in velocity of fluid occurs simultaneously with a decrease in pressure. According to this law, the velocity of air flowing through the runner results in air suction from the mould cavity to the runner.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Forces Acting on Cores and Mold”.

1. Cores generally experience a single force called gravitational force in the mould.

a) True

b) False

Answer: b

Explanation: When the core is placed in the mould, mainly two types of forces are present, one is the gravitational force acting on the core and another is buoyancy force which tries to lift the core in an upward direction due to the density difference between the core and metal. Core is generally lighter than the metal, which is used for the casting process.

2. In the mould, the heat experienced by the core is much severe than that of experienced by the mould wall.

a) True

b) False

Answer: a

Explanation: In the mould, the core is surrounded by the molten metal, so it experiences more thermal load as compared to the mould wall. The mould wall experiences the heat which is exposed to the molten metal from one side only, but in the case of the core it is surrounded from all the sides. So, the heat experienced by the core is much severe.

3. The buoyancy force is generated only due to the weight of the core inside the mould.

a) True

b) False

Answer: b

Explanation: In the mould, the core experiences the static pressure as well as the weight of the core. When these two worked together in combination, then there is a lifting of the core due to the force which is called as buoyancy force. This force acts onto the core because of the density difference of the molten metal and the core material used.

4. Refractoriness required in the core should be lower than that required in the moulding sand.

a) True

b) False

Answer: b

Explanation: Thermal load experienced by the core is much greater than that of experienced by the mould walls. So it is required that the core is able to bear the mechanical loading as well as the thermal loading. So, refractoriness required in the core should be higher than that required in the moulding sand.

5. Coarse sand grains of the core material can improve the refractoriness of the core.

a) True

b) False

Answer: a

Explanation: The coarse sand grains of the core material are used so that the better refractoriness of the core can be achieved. Sometimes special binders are also used in the core making process to induce better mechanical and thermal properties in the core like hot strength which is very important because core experiences extreme thermal load.

6. Collapsibility of the core material is not considered in the core making process.

a) True

b) False

Answer: b

Explanation: Collapsibility of the core material is very important and required in the core making process because after the solidification the core is pressurized from all the sides due to contraction of molten metal in the mould. So, the core is expected to collapse under these situations. And if it does not collapse then it causes defects like hot tearing and cracks in the castings.

7. Friability and crumbling are the properties which help in removing the core material from the solidified casting.

a) True

b) False

Answer: a

Explanation: Friability and crumbling are the properties of the core material which helps in breaking and removing of core from the solidified casting part. So, these two properties are important in breaking of cores. Removal of the cores becomes easier when the friability and crumbling properties of the core sand is better.

8. Green sand core is normally used for producing shallow features in the casting components.

a) True

b) False

Answer: a

Explanation: In general, the strength of the green sand core is less. So it cannot be used in the production of castings with deep or complex features, means it is normally used for producing the shallow features in the casting components. Because when the castings are made with deeper features, then the cores will have tendency to get break. So for limited features, green sand cores are preferred.

9. Increase in content of the binders in the core sand always increases the porosity of the core material.

a) True

b) False

Answer: b

Explanation: Increase in content of the binders in the core sand basically holds the sand grains together tightly and reduces the pore size in the core sand. So generally, there is a tendency for a reduction in the porosity of the core material. And the hardness of core sand increases continuously with the increase in the concentration of the binders.

10. Centrifugal casting is a method of casting which works on the principle of centrifugal force.

a) True

b) False

Answer: a

Explanation: Centrifugal casting is a technique which works on the principle of centrifugal force. Centrifugal force is a force that draws a rotating body away from the axis of rotation. This is basically caused by the inertia of the body. In this method of casting, molten metal is poured in the horizontal mould which rotates at high speed to form hollow castings.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Mold-Metal Reaction”.

1. With what does iron react to give out Ferrous Oxide?

a) Carbon dioxide

b) Nitrogen

c) Ozone

d) Oxygen

Answer: d

Explanation: Iron when reacts with Oxygen gas, it produces the compound, ferrous oxide. Ferrous oxide is an inorganic compound and possesses black colored appearance.

2. What is the chemical formula of fayalite?

a) FeO 2 SiO 2

b) FeOSiO 2

c) FeO 3 SiO 2

d) FeO 2 SiO 3

Answer: b

Explanation: The chemical representation of the compound fayalite is given by FeOSiO 2 . Fayalite is also known by the name, iron chrysolite.

3. What is the chemical formula of silica?

a) SiO

b) SiO 2

c) SiO 3

d) SiO 4

Answer: b

Explanation: None.

4. Silica reacts with what to give out fayalite?

a) Iron

b) Iron Sulphate

c) Iron Oxide

d) Iron Carbide

Answer: c

Explanation: In the formation of the compound fayalite (FeOSiO 2 ), Iron oxide reacts with silica to give out the compound fayalite or iron chrysolite.

5. What percent of magnesium is used in mold metal reactions?

a) More than 1%

b) More than 2%

c) More than 3%

d) More than 4%

Answer: a

Explanation: In the mold metal reactions, there is extremely less amount of magnesium used. Approximately more than 1% of magnesium is used in the reactions containing light alloys.

6. Which metal in aluminium alloy reacts with water to give out hydrogen filled pinholes?

a) Manganese

b) Iron

c) Magnesium

d) Aluminium

Answer: c

Explanation: Magnesium which is present in small quantity inside the light alloy, when reacts with water, causes the formation of hydrogen filled pinholes.

7. What is the condition for mold metal reaction to take place?

a) Radiating contact between gas and metal

b) Direct contact between gas and metal

c) Radiating contact between gas and oxide film

d) Direct contact between gas and oxide film

Answer: b

Explanation: For mold – metal reaction to take place, the condition is that there has to be direct contact between the gas and the metal.

8. How can the pinholes be reduced?

a) Oxidizing

b) Deoxidizing

c) Adding ozone

d) Adding calcium carbonate

Answer: b

Explanation: When pinholes are being produced more than necessary, the metal-mold reaction has to be deoxidized, which can cause the pinholes to reduce.

9. What is differential freezing?

a) Increase in oxygen concentration

b) Increase in nitrogen concentration

c) Increase in carbon concentration

d) Increase in hydrogen concentration

Answer: d

Explanation: When there is an increase in the hydrogen concentration of the metal – mold reaction, then that phenomena is called differential freezing.

10. In light alloys, metal – mold reaction can be suppressed by adding Helium.

a) True

b) False

Answer: b

Explanation: In light alloy, metal – bond reaction can be suppressed, but not by using Helium, but by using Boric acid and ammonium bi-fluoride.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Green Sand Mould”.

1. In a green sand moulding process, uniform ramming leads to _____

a) uniform flow of molten into the mould cavity

b) less chance of gas porosity

c) less sane expansion type of casting defect

d) greater dimensional stability of the casting

Answer: d

Explanation: Uniform ramming of sand is very necessary for green sand moulding process. Uniform ramming of sand during mould preparation improves mould strength, and makes it dimensionally stable. Uniform ramming done to obtain a smooth and hard casting surface which prevents break out.

2. In green sand mould, what is the indication of the word green?

a) It shows polymeric mould has been cured

b) Mould is green in color

c) Mould contains moisture

d) Mould has been totally dried

Answer: c

Explanation: Green sand mould contains 3-6 % of water, due to containing of moisture it is termed as green sand. Green sand has enough strength so that the constructed mould retains its shape. Moisture makes the sand more feasible and 95% reusable.

3. Which of the following is not a property of a sand mould?

a) Fluidity

b) Strength

c) Collapsibility

d) Permeability

Answer: a

Explanation: Fluidity is the property of molten metal, which is used to describe the capability of the molten metal to fill mould cavities. Solidification interval, viscosity and surface tension are the factors which help in determining the fluidity of the molten metal.

4. Hardness of green sand mould can be increase by _____

a) increase in permeability

b) decrease in permeability

c) increase in moisture content beyond 6 percent

d) increase in both moisture content and permeability

Answer: b

Explanation: A decrease in permeability usually indicates a closed structure in the rammed sand, and if the decrease continues, it will lead to tighter packing and fewer voids hence increase in hardness of the green sand mould. This increase in hardness can be measured by mould hardness tester.

5. What is the advantage of having a low bulk density of a sand-mix?

a) Higher strength

b) Good refractoriness

c) Higher flow ability

d) Higher permeability

Answer: d

Explanation: Low bulk density of sand mix results in equal size of grains with smooth round shape, this further results in increase in volume of voids due to less bulk density and hence a higher permeability which permits an easy outflow of the gases from the molten metal.

6. Which test is performed for the study of grain size distribution of moulding sand?

a) Screening test

b) Whirl test

c) Crushing test

d) Shearing test

Answer: a

Explanation: Screening test is performed by taking a fixed sample weight of sand and screening it through standard sieves. It is accomplished by shaking the sieves. The amount of sand that collects in the different sieves is then plotted, and then a distribution of grain size is computed.

7. Which of the following reasons stand for the crumbling of green sand mould?

a) The sand grains are not adequately bonded

b) Excess of water and clay mixture

c) Due to the presence of impurities in the green sand mould

d) Fine grain size

Answer: a

Explanation: Sand mould crumbles because moulding sand is not adequately compacted in the flask. Clay, together with water acts as a bonding agent and the organic additives also save the mould from crumbling by burning out at high temperatures and make room for the moulding sand to expand.

8. Refractoriness of the green sand mould shows _____

a) High strength

b) Toughness

c) High temperature resistant

d) High porosity

Answer: c

Explanation: Refractoriness is the ability of the moulding material to withstand the high temperatures of the molten metal to be poured so that it does not get fused with the metal. The refractoriness of the silica sand is highest. Refractoriness is measured by the sinter point of the sand.

9. In the given below graph, which curve represents the permeability of the green sand mould with the % of the water content?

casting-questions-answers-green-sand-mould-q9

a) a

b) b

c) c

d) d

Answer: c

Explanation: There is optimum water content for the permeability considerations. At a lower water content, dry clay powder, being finer than sand grains, fills up the voids between the sand particles, and thus reduces the permeability. Beyond the optimum water content, water itself fills up the voids and reduces the permeability.

10. Which of the following sands has the highest thermal conductivity?

a) Silica sand

b) Zircon sand

c) Chromite sand

d) Olivine sand

Answer: b

Explanation: It has low coefficient of thermal expansion. Due to high density and high chilling power, zircon sand has high thermal conductivity. These properties of the zircon sand make it very useful in controlling zircon sand, which is used as refractory bedding material.

11. Bentonite is commonly used as bonding material for dry sand cores.

a) True

b) False

Answer: a

Explanation: Bentonite is a type of clay which used as a bonding material because bentonite can absorb more water, which increases its bonding power, so that it can be used for drilling mud, purification and as a binder, absorbent, groundwater barrier etc.

This set of Casting Interview Questions and Answers for Experienced people focuses on “Functions of Gating Systems”.

1. For the functioning of the gating system, which of the following factors need not be controlled?

a) Type of sprue

b) Size of runner

c) Temperature of molten metal

d) Type of riser

Answer: d

Explanation: For the most proper functioning of the gating system, all the above factors should be taken into considerations, but not the type of riser.

2. Sprues up to what diameters are round in section?

a) 10mm

b) 20mm

c) 30mm

d) 40mm

Answer: b

Explanation: Sprues up to a diameter of 20mm cross section are round in shape. Sprues required with a larger cross section are known to be rectangular in shape.

3. What prevents the liquid metal from entering the gate?

a) Gate basin

b) Sprue

c) Runner

d) Riser

Answer: a

Explanation: A gate basin plays a very vital role in stopping the liquid metal flow. A gate basin does not allow the turbulently flowing liquid metal to enter the gate.

4. When would dross and slag tend to float on the metal surface?

a) When pouring basins are doubled

b) When pouring basins are made large

c) When pouring basins are made small

d) When pouring basins are removed

Answer: b

Explanation: The metal could be stopped from entering the sprue, and would cause the dross and slag to float on the metal surface, when the pouring basins are made large.

5. Which of the following helps connecting runner and the mold cavity?

a) Sprue

b) Riser

c) Gate

d) Pouring cup

Answer: c

Explanation: One or more than one gates can be employed in the apparatus, as these gates are the links connecting the runner and the mold cavity.

6. Which of the following is not a type of a gate?

a) Top gate

b) Bottom gate

c) Parting gate

d) Middle gate

Answer: d

Explanation: Among the given types, middle gate is not a type of gate. Gates are classified into top, bottom and side gate only.

7. Which of the following gate is also called as ‘drop gate’?

a) Top gate

b) Bottom gate

c) Parting gate

d) Middle gate

Answer: a

Explanation: Top gate is also known by the name of drop gate. This is because the molten metal simply gets dropped down through this gate on the sand beneath.

8. Which of the following gates is used for making stove plate castings?

a) Edge gate

b) Wedge gate

c) Ring gate

d) Finger gate

Answer: b

Explanation: Among the following, edge gate, ring gate and finger gate, are not used for the making of stove plate castings. A wedge gate is used when a stove plate casting has to be made.

9. Which of the following gates is not favourble for non ferrous castings?

a) Top gate

b) Bottom gate

c) Parting gate

d) Middle gate

Answer: a

Explanation: When a non ferrous casting is made to drop from the top gate, there is a tendency of it to form dross. Hence, top gates are not favourable for non ferrous castings.

10. Ring gates retain slag.

a) True

b) False

Answer: a

Explanation: Ring gates hinder the fall of liquid with a core. These ring gates are observed to retain slag.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Gating Design”.

1. The liquid metal that runs through the channels without friction in the mould obeys which of the following theorem?

a) Bernoulli’s theorem

b) Clausius theorem

c) Helmholtz’s theorem

d) Carnot’s theorem

Answer: a

Explanation: As the metal enters the pouring basin, it has the highest potential energy with no kinetic or pressure energies. But as the metal moves through the gating system, potential energy converts into kinetic energy. Thus it obeys the Bernoulli’s theorem.

2. Which of the following flows is responsible for too less pouring time of molten metal in the mould?

a) Laminar flow

b) Viscous flow

c) Turbulent flow

d) Irrotational flow

Answer: c

Explanation: Too less pouring time is caused by turbulent flow of nature of the molten metal. The mixing and collisions of molecules make the change in momentum and molecules get accelerated and hence high velocity, that cause the less pouring time of molten metal in the mould.

3. What will be the optimum pouring time for cast iron whose mass is 100 kg and a thickness of 25 mm? Fluidity of iron is 32 inches?

a) 24.98

b) 18.2

c) 31.32

d) 14.8

Answer: a

Explanation: Pouring time = K[ 1.41 + T/14.59]√W sec.

where K = Fluidity of iron in inches/40

Pouring time = 32/40[ 1.41 + 25/14.59]√100 = 24.988 sec.

4. Which of the followings is the formula for calculating the choke area ?

a) 2W/dtC√2gh

b) W/dtC√2gh

c) W²/dtC√2gh

d) 2W³/dtC√2gh

Answer: b

Explanation: Choke area  = W/dtC√2gh, It is the main control area which meters the metal flow into the mould cavity so that the mould is completely filled within the calculated pouring time. Its unit is mm².

Where, W = Casting mass , t = pouring time , d = mass density ³,

h = Sprue height , g = Acceleration due to gravity ², C = Efficiency factor.

5. Which of the following methods is used for trapping the slag from entering steel casting into the mould?

a) Finn’s method

b) Down gate method

c) Whirl gate method

d) Euler’s method

Answer: c

Explanation: Whirl gate method utilizes the principle of centrifugal action to throw the dense metal to the periphery and retain the lighter slag at the centre. Also, the metal revolves 270 degree before reaching the exit gate so as to gain enough time for separating the impurities.

6. Which of the following materials require a longer pouring time?

a) Non-ferrous material

b) Grey cast iron

c) Ferrous alloys

d) Brass

Answer: a

Explanation: For nonferrous material, a longer pouring time would be beneficial since they lose heat slowly and also tend to form dross if a metal is poured too quickly, this dross makes the quality of the material poor and further defects induced in the material.

7. Which of the following is the purpose of runner extension?

a) To make smooth surface finish

b) To make the casting of specific size and shape

c) To remove slag and dross from the metal

d) To make fast cooling of molten metal

Answer: c

Explanation: The metal which moves first into the gating system is likely to contain slag and dross which should not be allowed to get into the mould cavity. This could be achieved by extending the runner beyond the in-gate so the clean metal can be expected to go into the mould after completely filling the runner extension.

8. Which of the following gating systems is useful for casting drossy alloys?

a) Pressurized gating system

b) Partially pressurized gating system

c) High pressurized gating system

d) Non-pressurized gating system

Answer: d

Explanation: Non-pressurized gating system has choke at the bottom of the sprue base, have total runner area and in-gate areas higher than the sprue area. In this system, there is no pressure existing in the metal flow system and thus it helps to reduce turbulence. Hence this system can be used for casting drossy alloys such as aluminum and magnesium alloys.

9. Casting yield of a non-pressurized gating system is _____

a) very high

b) 80%

c) very less

d) 50%

Answer: c

Explanation: Tapered sprues are invariably used with an unpressurized system. Casting yield of a non-pressurized gating system gets reduced because of the large metal involved in the runner and gates. This makes the wastage of material, to avoid this, a pressurized gating system is used.

10. Smallest in-gate area in the pressurized gating system causes_____

a) turbulency

b) low velocity

c) low viscosity

d) smooth running of molten metal

Answer: a

Explanation: In the case of a pressurized gating system, due to the smallest in-gate area it maintains a back pressure throughout the gating system. Because of this back pressure in the gating system, the metal is more turbulent and generally flows full.

11. What is the ratio of width to the depth of in-gates in general?

a) 1:2

b) 1:1

c) 4:1

d) 2:7

Answer: c

Explanation: In-gates are generally made wider compared to the depth, up to a ratio of 4. This facilitates in the severing of gating from the casting after solidification. And it reduces the actual connection between the in-gate and the castings so that the removal of the gating is simplified.

12. Why large or complex castings require multiple in-gates?

a) To make smooth surface finish of the casting

b) To make uniform flow

c) To have high strength of the casting

d) To have good toughness of the casting

Answer: b

Explanation: Large or complex castings require multiple in-gates to completely fill all the sections of the castings effectively. Runner area is also reduced after each in-gate, such that restriction on the metal flow would be provided to make more uniformity in the metal flow.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Functions of a Riser”.

1. Exothermic material does not contain which of the following metal oxide?

a) Cobalt

b) Copper

c) Iron

d) Magnesium

Answer: d

Explanation: Exothermic materials are those which generate a lot of heat because of exothermic chemical reactions. Exothermic materials do not include oxides of magnesium.

2. Iron oxide reacts with which metal to give aluminium oxide?

a) Iron

b) Aluminium

c) Copper

d) Zinc

Answer: b

Explanation: When iron oxide reacts with aluminium, aluminium oxide and free iron atoms are formed, and a lot of energy in the form of heat is released.

3. How many moles of iron oxide are needed to react with 8 moles of aluminium to form 4 moles of aluminium oxide?

a) 2

b) 8

c) 4

d) 6

Answer: c

Explanation: According to the exothermic reaction, when 4 moles of iron oxide would react with 8 moles of aluminium, 4 moles of aluminium oxide and 8 moles of iron atoms will be formed.

4. Up to what percent is the efficiency increased by using exothermic materials?

a) 65%

b) 70%

c) 755

d) 80%

Answer: b

Explanation: The use of exothermic materials causes to increase the efficiency by around 70%. The use of exothermic materials also causes the riser to be of only one-third its regular size.

5. Heat diffusivity does not depend on which of the following?

a) Thermal conductivity

b) Specific heat

c) Latent heat

d) Density of the material.

Answer: c

Explanation: Heat diffusivity depends on thermal conductivity, specific heat and the density of the material, by the formula heat diffusivity = 1/2. Hence, heat diffusivity does not depend on latent heat.

6. How high can solidification rate factor be increased by metal chills?

a) 12

b) 13

c) 14

d) 15

Answer: c

Explanation: The solidification rate can be increased by a factor as high as 14, relative to that which is obtained in sand molds, by metal chills.

7. Chills promote only directional solidification.

a) True

b) False

Answer: b

Explanation: In a particular portion of casting, to speed up the process of solidification, chills are used. Chills are used for directional solidification as well as progressive solidification.

8. With an increase in the volume of castings, how would it affect the freezing time?

a) Increase

b) Decrease

c) Will not change

d) No relation

Answer: a

Explanation: According to Chvorinov’s rule, freezing time is directly proportional to the square of the volume. Therefore, an increase in the volume of the casts will cause a lot of increase in the freezing time.

9. Which of the following materials are not used for making chills?

a) Steel

b) Cast iron

c) Copper

d) Zinc

Answer: d

Explanation: For making chills, steel, cast iron and copper is widely used. But zinc metal is not used for this. Copper is used even more for chilling, as it provides the highest conductivity.

10. External chills can be used again and again.

a) True

b) False

Answer: a

Explanation: External chills can be used over and over again many times. But the same cannot be said for internal chills.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Types of Risers”.

1. What is the general shape of an open riser?

a) Cubical

b) Trapezoidal

c) Cylindrical

d) Rounded

Answer: c

Explanation: The shape of an open riser is generally cylindrical. The top of the cylinder is open, causing the molten metal direct exposure to the atmosphere.

2. With an increase in the weight of riser, what would be the corresponding change in the yield?

a) Increase

b) Decrease

c) Will not change

d) Not related

Answer: b

Explanation: Weight of the riser and the yield of the casting are inversely proportional to each other, that is, with an increase in the riser, yield will decrease.

3. Which of the following factors is not considered in regards with directional solidification?

a) Riser diameter

b) Riser height

c) Riser location

d) Metal to be casted

Answer: d

Explanation: When directional solidification is taken into consideration, the size of the riser and its location are the factors, but the metal to be casted is not a factor of directional solidification.

4. With an increase in the initial volume, how does it affect the efficiency of the riser?

a) Increases

b) Decreases

c) Will not change

d) No relation

Answer: b

Explanation: The initial volume of the metal inside the riser and the efficiency of the riser are inversely linked with each other, that is, with an increase in the initial volume, there will be a decrease in the efficiency of the riser.

5. In solidification of a riser, which of the following cannot be used for insulation?

a) Insulation powder

b) Insulation sleeve

c) Insulation pad

d) Insulation clip

Answer: d

Explanation: For delaying the solidification in risers, insulation is done. Insulation powder, insulation sleeve and insulation pad can be used, but not an insulation clip.

6. Which of the following insulations slows down the radiation losses?

a) Insulation powder

b) Insulation sleeve

c) Insulation pad

d) Insulation clip

Answer: a

Explanation: Insulation powder is used for slowing down the process of retardation of radiation losses from the surface of the metal in the riser.

7. Which of the following will not affect insulation?

a) Charcoal

b) Graphite

c) Copper

d) Out hulls

Answer: c

Explanation: When there is an addition of a powdered form of charcoal, graphite or out hulls, there is an insulation effect in the riser, but not by the addition of copper.

8. An open riser is connected only at the top of the cope.

a) True

b) False

Answer: b

Explanation: An open riser is connected at the top of the cope, but may also have a connection at the side of the parting line.

9. With an increase in the weight of sprue, what would be the corresponding change in the yield?

a) Increase

b) Decrease

c) Will not change

d) Not related

Answer: b

Explanation: Weight of the sprue and the yield of the casting are inversely proportional to each other, that is, with an increase in sprue, yield will decrease.

10. A blind riser is bigger than an open riser.

a) True

b) False

Answer: b

Explanation: A blind riser can be made anywhere in the mold, and it occupies minimum area and volume, hence it is smaller as compared to an open riser.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Riser Design – 1”.

1. How can we eliminate the shrinkage cavity?

a) By increasing riser height

b) By reducing riser height

c) Reducing the number of risers

d) By using an open riser

Answer: a

Explanation: If riser height is reduced, the pipe will extend to cast cavity. Similarly, if less no of the riser is used it will not satisfy feeding distance. Open riser alone can’t help in reduction of the cavity. But by increasing length of the riser, the pipe can be controlled in riser itself eliminating shrinkage cavity in casting.

2. Which of the following can be used for increasing feeding distance?

a) Uniform temperature gradient

b) Negative temperature gradient towards the riser

c) No temperature gradient

d) Positive temperature gradient towards the riser

Answer: d

Explanation: If the temperature gradient is not there, the metal will not solidify. Same will happen in case of the uniform temperature gradient. In case of the negative thermal gradient, the metal will first solidify near riser which results in unsound casting. Hence positive thermal gradient is required so that metal will solidify near walls first hence feeding distance will be increased.

3. What will be the feeding distance  without using chill for a plate of thickness T?

a) 4.5√T + 2

b) 4.5√T

c) 6√T+2

d) 6√T

Answer: b

Explanation: Feeding distance will be equal to 4.5√T + 2 if we are using chill for a plate. For a bar, feeding distance will be 6√T without chill and 6√T +2 with chill. Thus, feeding distance will be equal to 4.5√T if we are not using chill during casting a plate.

4. How can we enhance the feeding distance during casting?

a) Reducing molten metal temperature

b) Increase fluidity

c) By using low thermal conductivity mold

d) Using sand mold

Answer: b

Explanation: Feeding distance reduces by reducing molten metal temperature and using a low thermal conductive mold. For sand casting, feeding distance will be low because heat extracted by sand is very less compared to metals. By increasing fluidity, metal can flow over a long distance which results in higher feeding distance.

5. When do we need more number of risers during casting?

a) Feeding distance is low

b) Feeding distance is high

c) Thermal conductivity of mold is high

d) Fluidity of molten metal is high

Answer: a

Explanation: If feeding distance is high, number of the isolated zone in casting will be less thus less number of risers required. For high thermal conductivity, the metal will solidify faster and high fluidity molten metal will flow over a long distance which will result in less number of risers. If feeding distance is low, we have to use more risers to overcome isolated liquid pools.

6. How can we calculate the solidification time?

a) Shrinkage volume consideration method

b) Modulus method

c) Novel research method

d) Chvorinov’s rule

Answer: d

Explanation: Shrinkage volume consideration method, Modulus method, and Novel research method are used for riser design. For calculation of solidification time, Chvorinov’s Rule is used. The Same rule can be modified for riser design called as Caine’s method.

7. Which of the following is a key parameter when we design a riser using Novel research method?

a) Modulus

b) Freezing ratio

c) Shape factor

d) Shrinkage volume

Answer: c

Explanation: Modulus is used for designing of riser using modulus method. The freezing ratio is a key parameter when we design riser using Caine’s method. Shrinkage volume is used when we use the shrinkage volume method. For Novel research method, we use shape factor and corresponding to this we find Y from casting databook which is the ratio of the volume of casting to the volume of the riser.

8. How many number of risers are required if we use chills with end chills if L is the length and T is the thickness of the plate in mm?

a) L ⁄ 4T

b) casting-questions-answers-riser-design-1-q8b

c) casting-questions-answers-riser-design-1-q8c

d) casting-questions-answers-riser-design-1-q8d

Answer: c

Explanation: If we are not using any chills, number of risers without end effect will be L ⁄ 4T and with end wall effect it will be casting-questions-answers-riser-design-1-q8b . If we are using chills at center as well as end, number of risers will be casting-questions-answers-riser-design-1-q8d . In case if we are using chills only at the ends number of risers required will be casting-questions-answers-riser-design-1-q8c .

9. Modulus method can be used for determining the dimensions of the riser.

a) True

b) False

Answer: a

Explanation: Yes, Modulus method can be used for determining height and diameter of the riser. In this method, we find modulus of casting and riser which is the ratio of volume and area. The ratio of modulus of the riser to that of casting is 1.2, and the ratio of riser height to its diameter is 1.5. By using these two equations dimension of the riser is estimated.

10. If feeding distance is more, the number of risers required will be more.

a) True

b) False

Answer: b

Explanation: Feeding distance is more implies molten metal can flow for a longer distance. This will result in very few mushy zones in the casting. Hence, if the mushy zone is less, the number of risers required will also be less.

This set of Advanced Casting Questions and Answers focuses on “Riser Design – 2”.

1. The main function of a riser is to maintain the escaping of gases from the casting during solidification.

a) True

b) False

Answer: b

Explanation: Basically, the main objective of the riser is to feed the casting during solidification so that no any kinds of shrinkage cavities are formed in the casting. Type of metal poured and the complexity of the casting is responsible for the requirement of risers in the casting system to produce castings.

2. Which of the following materials can have the negative volumetric shrinkage of the casting?

a) Aluminium

b) Steel

c) Zinc

d) Grey cast iron

Answer: d

Explanation: Different materials have different volumetric shrinkage, in which grey cast iron is the material which sometimes may have a negative shrinkage. This mainly occurs because of high carbon and silicon contents in the grey cast iron, which results in occurring of graphitization which increases the volume.

3. There is no requirement of any risers for the casting of grey cast iron.

a) True

b) False

Answer: a

Explanation: In grey cast iron, while solidification the process of graphitization occurs, this increases the volume of the casting and counteracts the metal shrinkage, so risers can be eliminated for the casting of grey cast iron. But for some metals like aluminium and steel, the volumetric contraction is very high, so elaborate risering is required.

4. Improper risering has always resulted in the formation of voids inside the castings.

a) True

b) False

Answer: a

Explanation: The main reason for the formation of voids inside the castings is that the liquid metal in the centre which solidifies in the end is not fed during the solidification of the castings; hence the liquid shrinkage ends up as a void. This can be avoided by proper design of the riser in the casting system.

5. The cooling characteristics of casting can be represented by the_____

a) volume to surface area ratio

b) product of volume and surface area

c) surface area to volume ratio

d) surface area to perimeter ratio

Answer: c

Explanation: Solidification is basically occurred by losing heat from the surfaces and the amount of the heat is given by the volume of the casting, and the cooling characteristics of casting are given by the surface area to volume ratio. Riser is also similar to the casting in its solidification nature; hence the riser characteristics can also be given by the ratio of its surface area to volume.

6. Which of the following relations is given by chvorinov for the solidification time of a casting?

a) t s = k 2

b) t s = k

c) t s = k 2

d) t s = k 3

Answer: a

Explanation: Chvorinov scientist has shown that the solidification time of a casting is directly proportional to the square of the ratio of volume-to-surface area of the casting and the constant of proportionality is known as mould constant. His relation is given by: t s = k 2 , where ts = solidification time, V = volume, SA = surface area, k = mould constant.

7. A sphere can be used as a riser because of its freezing ratio, which is greater than unity.

a) True

b) False

Answer: b

Explanation: Freezing ratio greater than unity is always preferred for the ability to feed the casting. Sphere could be used as a riser as its surface area to volume ratio is very low. But in sphere, the hottest metal being at centre, it is very difficult to use it for feeding to the casting, so a cylindrical type is always preferred.

8. Which of the following methods is used for the determination of optimum riser size?

a) RMS method

b) Modulus method

c) Finn method

d) Ring method

Answer: b

Explanation: For the finding of optimum riser size, modulus method is very easy to take in action, and empirically it is also established that if the modulus of the riser exceeds the modulus of the casting by a factor of 1.2, then the feeding during the solidification part of the casting would be satisfactory.

9. Which of the following factors is used to define the casting type in riser design?

a) Plating factor

b) Ranginess factor

c) Caine factor

d) Pseudo factor

Answer: b

Explanation: For the chunky type castings like a cube, the volume component can be neglected, but for the rangy castings, like as plate-like casting, the influence of the volume part becomes increasingly significant. So, it is very useful to have a parameter called ranginess factor , to define the casting type.

10. The core material should be highly refractory in nature to avoid any damages to it.

a) True

b) False

Answer: a

Explanation: In the casting of massive ring shaped bodies, the bore area is very small, so the bore experiences very high temperature that can damage or destroy the bore material, so in maximum cases, the designs are made to eliminate the use of cores or the highly refractory core materials are used to resist the high temperature.

11. In casting system, the riser is located at the lightest section to avoid any disturbance.

a) True

b) False

Answer: b

Explanation: In the casting system, the risers should be located at the heaviest sections to achieve a better casting with fewer defects, and because the heavier sections, themselves act as feeders for the thin sections. And variations in volume of riser must be done if the size of casting sections also varies.

12. Which of the following parts is used as exothermic materials or insulators for the increase in efficiency of the riser?

a) Chills

b) Feeding aids

c) Biscuit

d) Filler

Answer: b

Explanation: At the time of solidification, the shrinkages are produced in the castings which are eliminated by the use of a riser. The metal in riser should be in liquid form for a long period of time as to feed the casting till it solidifies. So feeding aids are used for this purpose, they can be either exothermic materials or insulators.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Directional Solidification”.

1. Which of the following materials has superior strength and rigidity at high elevated temperature?

a) Aluminium-based alloys

b) Copper-based alloys

c) Zinc-based alloys

d) Nickel-based alloys

Answer: d

Explanation: In the high temperature technology, the need for materials with superior strength, ductility and rigidity has been growing. Nickel-based alloys are the most widely used materials at the high elevated temperature, and super-alloys of it, are the greatest in the mechanical properties.

2. Directional solidification allows components to be produced from the melt in a single stage process.

a) True

b) False

Answer: a

Explanation: In the production of composite castings by directional solidification of eutectics, this allows the components are to be produced from the melt in a single stage process, by which there is intrinsic thermodynamic stability and also the chemical compatibility between the matrix and reinforcement of the casted composite component.

3. It is not easy to control the material at the microstructure level in the directional solidification.

a) True

b) False

Answer: b

Explanation: In directional solidification, material can be controlled over a wide range from well aligned to finely dispersed particles or fibers at microstructure level by the adjusting the various solidification conditions, in which several eutectic types are analyzed as potential materials for high temperature applications.

4. It is not possible to replace super-alloys by the directionally solidified high temperature eutectics.

a) True

b) False

Answer: b

Explanation: Directional solidification of binary or pseudo-binary eutectics is able to produce well aligned regular structures consisting of fibrous constituents. Such structures may offer a substantial hike in high-temperature strength and creep resistance. So easily, there can be a replacement of super-alloys by the directionally solidified eutectics.

5. Oxidation resistance should be the prime requirement for the high temperature structural applications.

a) True

b) False

Answer: a

Explanation: A primary requirement for high temperature structural applications is an adequate oxidation resistance at temperature more than 1000 ⁰C. So, attention must be focused on those alloys which have a high concentration of aluminium and silicon, however, these elements produce protective oxide scales of alumina and silica respectively to protect the material.

6. To achieve useful strength of the material at temperatures of 1000-1600 ⁰C, what should be the melting point temperature of the material?

a) 1000 ⁰C

b) 1300 ⁰C

c) 1600 ⁰C

d) More than 1600 ⁰C

Answer: d

Explanation: To achieve useful strengths at the temperatures of 1000-1600 ⁰C, melting points in excess of 1600 ⁰C are required. Most of the materials retain significant strength to approximately 0.5-0.6 of their absolute melting temperature, but for high strength, high melting point temperature is preferred.

7. Which of the following shows the relationship between the growth rate and inter-phase spacing?

a) λ 2 R = constant

b) λR 2 = constant

c) λ/R = constant

d) λ⁴R = constant

Answer: a

Explanation: The relationship between the growth rate  and inter-phase spacing  for the eutectic structure is given by: λ 2 R = constant, where the constant is related to the magnitudes of the liquid-us slopes at the eutectic temperature and the composition difference between the two phases.

8. Which of the following furnaces is used for the directional solidification of cast ingots of eutectic?

a) Pneumatic zone furnace

b) Cupola furnace

c) Hydraulic zone furnace

d) Optical floating zone furnace

Answer: d

Explanation: The drop cast ingots are directionally solidified using an optical floating zone furnace, in which radiation is emitted from a xenon lamp and focused on the specimens enclosed in a quartz tube which is basically evacuated first and back filled with the argon gas. And then drop-cast rods are used as the feed material for the performing of other operations.

9. Which of the following methods is used for the cutting of directionally solidified rods or castings?

a) Thermal cutting

b) Electro-discharge machining

c) Water jet cutting

d) Weld cutting

Answer: b

Explanation: The directionally solidified castings are cut transversely and longitudinally by the application of electro-discharge machining. In this method, material is removed from the work-piece by discharging of current between the electrodes, results in an electric voltage. This method is also known as spark machining.

10. In the process of directional solidification, weight always remains constant for all the materials.

a) True

b) False

Answer: b

Explanation: According to the conservation of mass, weight remains constant until occurring of any reaction in the process. So, in some cases of materials, weight loss can occur by evaporation when the vapour pressure is very high. For example, vapour pressure of chromium is relatively high, about ten times the vapour pressure of silicon at the processing temperatures.

11. Directional solidification always ends at the sprue part and starts from the end of the casting.

a) True

b) False

Answer: a

Explanation: Directional solidification is always started from the farthest end of the casting and finishes at the sprue part of the casting system. Another term is the progressive solidification, in which solidification starts from the walls of the casting that is also known as parallel solidification.

12. Progressive solidification is better than the directional solidification and it is independent to the geometry of mould.

a) True

b) False

Answer: b

Explanation: Solidification is greatly affected by the geometrical shape of the mould cavity; variation in geometry causes the change in heat flow which leads to altering of solidification. In the condition of progressive solidification, there is always a chance of shrinkage defects. So it cannot be better than directional solidification.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Aspiration Effect”.

1. Which of the following items is used for trapping impurities from entering the mould?

a) Facing sand

b) Core

c) Skim bob

d) Pouring basin

Answer: c

Explanation: Skim bob is a trap placed in a horizontal gate to prevent heavier and lighter impurities from entering the mould. It removes the dross if not strained by strainer and the sand also. Skim bob appears like as shown in the below figure.

casting-questions-answers-aspiration-effect-q1

2. Which of the following effects can produce porous castings?

a) Aspiration effect

b) Viscous effect

c) Shapiro effect

d) Turbulent effect

Answer: a

Explanation: When the mould is made, care should be taken to ensure that the pressure anywhere in the liquid metal stream does not fall below the atmospheric pressure. Otherwise, the gases originating from baking of the organic compounds in the mould will enter the molten metal stream, producing porous castings. This is known as Aspiration effect.

3. In the given below figure of Mechanism of vacuum generation, point ‘2’ is the indication of _____

casting-questions-answers-aspiration-effect-q3

a) Poynting point

b) Vena contracta

c) Stack point

d) Steric point

Answer: b

Explanation: The constricted region at point 2 in the figure is known as vena contracta. A sudden change in the flow direction cause the aspiration effect and thus vacuum as the liquid metal stream contracts around a sharp corner due to the momentum effect. To avoid vacuum, the mould is made to fit the vena contracta.

4. Sprue design is made tapered instead of straight ___________

a) To easy flow of molten metal

b) To have smoothness in the metal flow

c) To maintain the pressure balance

d) To avoid the erosion of mould sand

Answer: c

Explanation: Pressure balance is maintained, to avoid the negative pressure , the sprue should be tapered. The ideal shape of the sprue is parabola but to reduce the manufacturing difficulty shape of the sprue is considered as tapered cylinder.

5. Splash core is used _____

a) to reduce the eroding force of the liquid metal

b) to make the flow smooth and slow

c) to remove dross from the molten metal

d) to prevent heavier impurities from entering the mould

Answer: a

Explanation: A ceramic splash core is placed at the end of the sprue reduces the eroding force of the liquid metal stream. It acts the same as pouring basin that also reduces the eroding force of the liquid metal coming directly from the furnace as well as maintains a constant pouring head.

6. The primary purpose of sprue in casting mould is to _____

a) act as a reservoir for molten metal

b) feed the casting at rate consistent with the rate of solidification

c) feed molten metal from the pouring basin to the gate

d) help feed the casting until all solidification takes place

Answer: c

Explanation: Sprue is a connecting passage between pouring basin and runner for molten metal in the tapered form to avoid the aspiration effect so that pressure equally maintained in the column of liquid metal streaming to the mould.

7. In the given below figure of outlet dimensions to prevent vacuum generation, what should be the relation between d’ and d?

casting-questions-answers-aspiration-effect-q7

a) d’/d = 1.3

b) d’/d > 2

c) d’/d = 2

d) d’/d > 2.2

Answer: a

Explanation: To avoid creation of vacuum or in other words, a sharp change in the flow direction is avoided. This achieved by maintaining the value of d’/d approximately equal to 1.3. Where d is the runner diameter and d’ is the entrance diameter.

8. What is the purpose of strainer in the gating system?

a) To make uniform flow

b) To make smooth surface finish of the casting

c) To remove dross from the molten metal

d) To create positive pressure throughout to avoid aspiration effect

Answer: c

Explanation: Ceramic strainer in the sprue removes dross and prevent slag from entering to the castings. Strainer additionally useful to laminize the flow. A typical strainer might be a cylinder of 30-50 mm diameter, 10-20 mm long, containing ten or more holes, of diameter approximately 3-5 mm.

9. Which of the following gases is responsible for the Pin hole porosity in the molten metal?

a) Hydrogen

b) Nitrogen

c) Oxygen

d) Carbon-dioxide

Answer: a

Explanation: This is caused by the dissociation of water inside the mould cavity. As the molten metal gets solidified, it loses temperature which decreases the solubility of gases by expelling the dissolved gases. The hydrogen while leaving the solidifying metal would cause long pin holes showing the path of escape.

10. Which of the following can be the reason for the aspiration effect?

a) High pressure of molten metal

b) High pouring temperature of molten metal

c) Low viscosity of molten metal

d) High viscosity of molten metal

Answer: b

Explanation: High pouring temperature which increases the amount of gas absorbed  by the molten metal in the furnace, in the ladle and during the flow in the mould. When gases not allowed to escape, would be trapped inside the casting and weaken it.

11. Which of the following reasons is the incorrect reason for the blow holes inside the castings?

a) Presence of moisture in the mould

b) Lower venting

c) Lower permeability of the mould

d) High pressure of the molten metal

Answer: d

Explanation: Moisture left in the mould and core converted into steam because of the presence of heat in the molten metal. The parts of steam entrapped in the castings end up as blow holes, same as the aspiration effect. Lower venting and lower permeability of the mould is also responsible for the blow holes inside the castings.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Effects of Friction and Velocity Distribution”.

1. The energy loss due to friction  in a circular conduit  is given by_____

a) Ef = 4fLv̅²/2D

b) Ef = 8fLv̅²/2D

c) Ef = 4fLv̅³/2D

d) Ef = 4fLv̅²/D

Answer: a

Explanation: Ef = 4fLv̅²/2D is the energy loss due to friction in a circular conduit. The frictional losses are present due to sudden contraction or enlargement of the flow cross-sections. Where, v̅ = Average velocity, D = Diameter of the conduit, L = Length of the conduit and f = friction factor.

2. Which of the following reasons is the incorrect reason for frictional losses in the conduit?

a) Gradual change in flow direction

b) Sudden contraction of the flow cross-sections

c) Sudden enlargement of the flow cross-sections

d) Due to irrotational flow of molten metal

Answer: d

Explanation: In real fluids, the frictional losses are always present, especially when there is a sudden contraction or enlargement of the flow cross-sections and also due to a gradual change in the flow direction, e.g., in a 90° bend and similar other fittings.

3. Why is Velocity of a fluid in contact with any solid surface is zero?

a) Due to cohesive forces in the fluid particles

b) Due to low velocity of fluid

c) Due to no slip condition

d) Due to high intermolecular forces between the fluid particles

Answer: c

Explanation: Velocity of a liquid metal in the sprue and the gate is not uniform across the cross-sections. It is maximum at the axis of the conduit and zero at the solid surface due to high adhesive bonding between the surface and the fluid particles, which is responsible for viscosity and results in no slip condition.

4. Which of the following terms is modified in the integrated energy balance equation for non-uniform velocity distribution?

a) Potential energy

b) Kinetic energy

c) Pressure energy

d) Thermal energy

Answer: b

Explanation: The non-uniform velocity distribution can be accounted for by modifying the kinetic energy term in the integrated energy balance equation by replacing the ² term by v̅²/β, where v̅ is the average velocity and β is a constant. β is equal to 0.5 for laminar flow and 1 for turbulent flow in a circular conduit.

5. The velocity distribution within the conduit depends on _____

a) shape of the conduit and nature of flow

b) temperature of the molten metal

c) impurities present in the molten metal

d) type of the molten metal

Answer: a

Explanation: The velocity distribution within the conduit depends on the shape of the conduit and the nature of flow . The velocity profile is parabolic in laminar flow and is logarithmic in turbulent flow. Shape of the conduit means cross-sectional area which varies in inverse proportion to the velocity.

6. For a smooth conduit, which of the following is the value of friction factor  for laminar and turbulent flow respectively?

a) 10/Re, 0.0791 -0.25

b) 16/Re, 0.0791 -0.25

c) 10/Re, 0.0771 -0.25

d) 16/Re, 0.0171 -0.25

Answer: b

Explanation: For a smooth conduit, the value of f is given by the equations

f = 16/Re for laminar flow ,

f = 0.0791 -0.25 for turbulent flow ,

Where, Re is Reynolds number.

7. Friction loss factor (e ғ ) in the conduit of liquid metal depends on _____

a) temperature of the molten metal

b) presence of dross in the molten metal

c) ratio of the flow area and Reynolds no. of the flow

d) whirling of the molten metal

Answer: c

Explanation: e ғ is the friction loss factor and it depends on the ratio of the flow area and Reynolds number of the flow. For a laminar flow, the length and diameter of the smaller flow cross-section have to be taken into account. The value of e ғ depends on whether the flow area is enlarging or contracting in the direction of flow.

8. Given figure below, shows a ladle having an internal diameter of 1 m with a capacity height of 1.2 m. It has a nozzle of 75 mm exit diameter. What is the mass flow rate in kg/sec?

Take C D  = 0.96, ρ  = 2700 kg/m 3

casting-questions-answers-effects-friction-velocity-distribution-q8

a) 34.22

b) 46.38

c) 55.34

d) 60.10

Answer: c

Explanation: The mass flow discharge rate is given by ṁ = ρAnCD√2gH

Where, CD  = 0.96, ρ  = 2700 kg/m 3 ,

 = 1.2 m and g  = 9.81 m/s 2

And An  = π/4 *  2 m 2 = 4.4*10 -3 m 2

ṁ = 2700*4.4*10 -3 *0.96√2*9.81*1.2 kg/sec

ṁ = 55.34 kg/sec.

9. In the given figure of Entry with rounded corner type of changes in flow geometry, the value of friction loss factor (e ғ ) is_____

casting-questions-answers-effects-friction-velocity-distribution-q9

a) 0.33eғs

b) 0.5eғs

c) 2eғs

d) eғs

Answer: a

Explanation: eғ = 0.33 eғs, where eғ is the friction loss factor. The value of eғ depends on whether the flow is enlarging or contracting in the direction of flow. And eғs refers to the value corresponding to a sharp change of geometry with identical initial and final dimensions.

10. Which of the following gating designs is used to avoid the splashing of the molten metal in the mould?

a) Vertical gating

b) Horizontal gating

c) Inclined gating

d) Bottom gating

Answer: d

Explanation: In the case of bottom gating design the liquid metal is filled in the mould from bottom to top, thus it avoids the splashing of the molten metal in the mould that can cause erosion. And this design also prevents the oxidation which is associated with the vertical gating.

11. Gating design for a mould of 50cm*25cm*15cm is shown in below figure. The cross-sectional area of the gate is 5 cm 2 . Neglecting friction and velocity distribution effects, what is the filling time  for the design ?

casting-questions-answers-effects-friction-velocity-distribution-q11

a) 19.25

b) 21.86

c) 34.21

d) 10.39

Answer: b

Explanation: H  = 15 cm, from the figure.

v  = √2gH = √2*981*15 cm/sec = 171.6 cm/sec.

V  = 50*25*15 cm³ and A  = 5 cm 2 .

As we know, t = V/Av

So, t  = 50*25*15/5*171.6 sec = 21.86 sec.

12. Which of the following ways can use for stopping the rapid solidification of the molten metal in the mould?

a) By having the mould of high permeability

b) By making a uniform flow of molten metal

c) By creating high pressure on the molten metal

d) By using too much superheat

Answer: d

Explanation: When the liquid metal is poured very slowly, then the time taken to fill up the mould is rather long and the solidification may start even before the mould has been completely filled up. This can be avoided by using too much superheat, but this creates the gas solubility problem which is not good for castings.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Furnaces for Melting”.

1. For melting of cast iron, which of the following furnace is used?

a) Rotary furnace

b) Cupola furnace

c) Pit furnace

d) Electric furnace

Answer: b

Explanation: Cupola is a heavy furnace and has the capability to melt down heavy metals like cast iron. Hence, the Cupola furnace is mostly used to melt cast iron for casting purposes.

2. Why is sand bed prepared for melting of metal in Cupola furnace?

a) It provides a refractory bottom

b) It soaks the moisture from the metal

c) It conducts the heat faster and uniformly

d) None of the mentioned

Answer: a

Explanation: A sand bed needs to be prepared because it provides a necessary refractory bottom for molten metal and coke.

3. What is the function of slag hole in a cupola furnace?

a) To tap the slag generated

b) To generate the slag

c) To allow outflow of gases

d) All of the mentioned

Answer: a

Explanation: Slag hole is a tapping hole in a cupola furnace. Through which slag generated during the melting process is tapped.

4. Incoming air pressure and quantity in cupola furnace are controlled by which of the following element?

a) Tuyeres

b) Tapping spout

c) Wind box

d) Blast pipe

Answer: c

Explanation: The air enters the cupola through the tuyers. But the air blowers in the wind box controls the requisite pressure and quantity of air coming inside.

5. Which of the following chemical compound, is the most common flux added to the charge in a cupola furnace?

a) Coke

b) Methane

c) Carbon dioxide

d) Limestone

Answer: d

Explanation: Limestone (CaCO 3 ) is used as Flux in cupola furnace in a proportion of about 2-4% of the metal charge.

6. Which of the following metal has a melting point of about 1537 o C and latent heat of fusion 65.0 cal/g?

a) Nickel

b) Copper

c) Zinc

d) Iron

Answer: d

Explanation: Iron is the metal having a melting point of about 1537 o C and latent heat of fusion of 65.0 cal/g. It has a mean specific heat of 0.141 cal/g- o C and heat required for melting 1 Kg of iron is 1168 kJ.

7. Electric arc furnaces are most suitable for which of the following type of material?

a) Ferrous

b) Non-Ferrous

c) Both ferrous and nonferrous

d) Neither ferrous nor nonferrous

Answer: a

Explanation: Electric furnaces are more suitable for ferrous material in a larger capacity.

8. There is no direct contact of flame and metal in which of the following type of furnace?

a) Cupola

b) Crucible

c) Electric arc

d) Induction

Answer: b

Explanation: In Crucible furnace, metal is placed in a crucible of refractory material. The crucible is heated with electric resistance.

9. What is hearth in a furnace?

a) The electrodes are often called hearth

b) The walls of the furnace

c) The bowl shaped bottom of the furnace

d) The dome shaped roof of the furnace

Answer: c

Explanation: The hearth is that bowl shaped bottom of the furnace. It is made up of a high refractory material .

10. Why are flux added to the charge  during melting of a metal?

a) To increase carbon content

b) To increase refractoriness

c) To add specific oxides

d) To remove specific oxides

Answer: d

Explanation: The flux is a chemical substance, added to the metal while melting it to remove oxides present in the metal.

11. In an induction furnace, mixing and melting rates are altered by?

a) Controlling the temperature ranges only

b) Controlling the number of electrodes used only

c) Controlling power and frequency of current only

d) All of the mentioned factors

Answer: c

Explanation: Due to the principle of induction used, the electromagnetic fields are produced. These EMF’s are used to stir the metal. Hence, controlling the power and frequency, Mixing and melting rates can be altered.

12. Which of the following is/are the advantage of an Induction Furnace?

a) Higher yield

b) Cleaner melting

c) Compact Installation

d) All of the mentioned

Answer: d

Explanation: Advantages offered by Induction Furnace are higher yield, faster startup, cleaner melting, natural stirring and compact installation.

13. Which of the following metal has a melting point of about 420oC and latent heat of fusion 26.3 cal/g?

a) Nickel

b) Copper

c) Zinc

d) Iron

Answer: c

Explanation: Zinc is the metal having a melting point of about 420oC and latent heat of fusion of 26.3 cal/g. It has a mean specific heat of 0.101 cal/g o C and heat required for melting 1 Kg of Zinc is 285 kJ.

14. Which of the following metal has a melting point of about 660oC and latent heat of fusion 92.7 cal/g?

a) Aluminium

b) Lead

c) Magnesium

d) Tin

Answer: a

Explanation: Iron is the metal having a melting point of about 660oC and latent heat of fusion of 92.7 cal/g. It has a mean specific heat of 0.237 cal/g o C and heat required for melting 1 Kg of iron is 1022 kJ.

15. Gas-Fired burner is used in which of the following furnace?

a) Induction Furnace

b) Reverberatory Furnace

c) Cupola Furnace

d) Crucible Furnace

Answer: b

Explanation: Reverberatory furnace use gas-fired burner, located higher in the Furnace transferring heat by radiation to the wall and roof.

16. What is inoculation of cast iron?

a) Addition of sulphur alloys

b) Addition of silicon alloys

c) Addition of oxides

d) Addition of parent metal’s ore

Answer: b

Explanation: Inoculation of cast iron is the addition of certain silicon alloys to molten iron to produce changes in graphite distribution.

17. Why is inoculation done certain times during melting of cast iron?

a) To enhance its mechanical properties

b) To reduce the liquid shrinkage of metal

c) To enhance the surface finishing

d) All of the mentioned

Answer: a

Explanation: A certain amount of silicon alloys are added to the molten metal to enhance its mechanical properties and for reduction of chilling speed.

18. Which of the following is/are not used to melt material in casting industries?

a) Cupola furnace

b) Induction furnace

c) Ladle furnace

d) Crucible furnace

Answer: c

Explanation: All of listed are the furnaces used by metal foundry industries to melt down metal for casting purposes, except Ladle furnace.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Gases in Metals”.

1. Which of the following metals comes in an exothermic group of metals when the solubility of hydrogen is concerned?

a) Iron

b) Titanium

c) Magnesium

d) Nickel

Answer: b

Explanation: When the solubility of hydrogen is concerned, titanium comes in an exothermic group of metals which absorb more hydrogen than endothermic metals . Further, in exothermic metals, the solubility of hydrogen decreases with temperature. The reverse is true for endothermic metals.

2. Which of the following equations represent the solubility  of the hydrogen in the metals?

a) S = C exp[-E s /]

b) S = C exp[-E s *]

c) S = C log[-E s /]

d) S = C log[-E s *]

Answer: a

Explanation: Solubility  of the hydrogen in the metals is expressed as S = C exp[-E s /], where E s  is the heat of the solution of 1 mol of hydrogen and θ is the absolute temperature with C and k as constants. Equation of solubility clearly shows that gas precipitation during cooling cannot take place in exothermic metals for which E s is negative.

3. Presence of hydrogen in endothermic metals causes lattice distortion.

a) True

b) False

Answer: b

Explanation: Hydrogen dissolves in lattice defects of endothermic metals, hence produces no distortion. In exothermic metals, hydrogen is believed to dissolve interstitially so it produces the lattice distortion in exothermic metals. 

4. Which of the following formulas show the Sievert’s law of percent of hydrogen  present in a melt?

a) H = K 2

b) H = K*pHa

c) H = K/pHa

d) H = K√pHa

Answer: d

Explanation: Sievert’s law states that the amount of hydrogen dissolved in a melt varies as % hydrogen present  = K√pHa, where pHa is the partial pressure of hydrogen in the atmosphere over the melt, and K is a constant.

5. Maintaining of hydrogen level to a minimum in a melt is very important because there is no simple dehydrogenating technique.

a) True

b) False

Answer: a

Explanation: There is no simple dehydrogenating addition to eliminating hydrogen in the form of slag. So, care should be taken to maintain the hydrogen level to a minimum. The method used for removal of hydrogen in which partial pressure of hydrogen is reduced by bubbling some other dry insoluble gas through the melt; this method is not easy and also causes many other problems.

6. Which of the following methods is best for preventing the solutions of gases in metals?

a) Bubbling of gas

b) Vacuum melting

c) Venting arrangement

d) Elements inclusion

Answer: b

Explanation: Vacuum melting is increasingly being used for preventing the solutions of gases in metals and the combinations of reactive elements in the melt. Additions in the ladle, rather than in the melt, have been found to be more effective for controlling the gases and chemical compositions.

7. Improper venting arrangement causes mechanical trapping of gases in metal castings.

a) True

b) False

Answer: a

Explanation: The gases in metals lead to faulty castings. In metal castings, the gases may be trapped mechanically by having improper venting arrangements, in such situations trapping of gases can be prevented by making proper venting arrangements in the mould.

8. Nitrogen cannot be used for ferrous and nickel based alloys in hydrogen removal technique because_____

a) it leads to form high dross in metal castings

b) it gives rise to porosity in metal castings

c) it affects the grain size

d) it generates blow holes in metal castings

Answer: c

Explanation: For ferrous and nickel based alloys, nitrogen cannot be used because it is soluble in these and also it may form nitrides which affect the grain size; therefore, in ferrous alloys in particular, accurate control of the nitrogen is necessary. In such situations, carbon monoxide bubbles are used.

9. In the hydrogen removal process, carbon monoxide for ferrous alloys removes not only hydrogen but also nitrogen.

a) True

b) False

Answer: a

Explanation: Carbon monoxide for ferrous alloys removes not only hydrogen but also nitrogen. So, for ferrous metals, a marked decrease in the solubility of nitrogen during the phase change may give rise to porosity in the castings. And the re-entry of nitrogen from the air is also prevented by the impermeable slag at the top of the melt.

10. Which of the following metals has the lowest liquid solubility  of hydrogen at atmospheric pressure?

a) Iron

b) Copper

c) Magnesium

d) Aluminium

Answer: d

Explanation: Hydrogen solubility is an acute problem in ferrous casting. Liquid solubility of hydrogen in aluminium is 7cc/kg, which is lowest comparatively to other metals. So, it is not very difficult to handle aluminium and chances of inclusion of gas are also very less due to less liquid solubility.

11. Variation in solubility of gases can cause the generation of gases in metal castings.

a) True

b) False

Answer: a

Explanation: At different temperatures and phases, the gases may be generated due to the variation in their solubility. And chemical reactions also lead to a generation of gases in metal castings. The gases most generally present are hydrogen and nitrogen, in which removal of hydrogen from the melt is very necessary for better castings.

12. Which of the following gases can be beneficial in imparting certain desirable qualities to the castings?

a) Oxygen

b) Nitrogen

c) Hydrogen

d) Carbon monoxide

Answer: b

Explanation: Nitrogen can be added in castings to impart desirable qualities. For example, when this gas is added to steels, it improves strength, fatigue life, corrosion resistance and many other properties. Nitrogen would affect these properties only if it remains very fine nitrides in solid solutions.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Casting Cleaning”.

1. Breaking of the sand mould is done after sufficient cooling of castings, to have_____

a) proper surface finish of castings

b) no any distortion to castings

c) high casting yield

d) less casting yield

Answer: b

Explanation: The sand mould is to be broken to extract the casting. But the breaking of the sand mould is to be done only when the castings are sufficiently cooled, since the metal at high temperature has very little strength, due to this it may cause distortion to the casting if breaking of mould is done before proper cooling of the mould.

2. Pressure change of a melt is responsible for the cooling rate of the castings in the mould.

a) True

b) False

Answer: b

Explanation: Pressure has no effects on cooling rate of castings; the cooling rate depends upon the casting thickness, the total mass as well as the type of mould. More the mass or density of the castings will show less cooling rate and more the surface area of castings will have fast cooling rate of the castings in the mould.

3. Which of the following types of mould will have the longest period of cooling time for the same castings?

a) Green sand mould of simple shape and size

b) Dry sand mould of simple shape and size

c) Dry sand mould of complex shape and size

d) Green sand mould of complex shape and size

Answer: c

Explanation: Dry sand mould of complex shape and size will have the longest period of cooling time, it is around 18-30 hours for 3000-5000 kg of mass of castings. The cooling time also depends upon the mass of the castings, for the same sand mould the cooling time can be reduced up to 50% if the mass of castings comes in the range of 1000-3000 kg.

4. Faster and uneven cooling of hot casting affects the castings badly or may cause several defects in the castings.

a) True

b) False

Answer: a

Explanation: When the hot casting is exposed to the air, there is likely to be faster and uneven cooling because of which the casting may wrap, crack or induce thermal stresses beneath the skin. The moulding sand provides a uniform cooling medium for the casting while producing least amount of internal stresses.

5. For ferrous alloys, the breaking of mould should be done at a temperature_____

a) 780 ⁰C

b) 850 ⁰C

c) above 700 ⁰C

d) below 700 ⁰C

Answer: d

Explanation: Ideally, the moulds should be broken at a temperature when no transformation occurs. For ferrous alloys, the breaking should be done at a temperature below 700 ⁰C. If the castings are fragile and thin, they should be removed at a temperature as low as 400 ⁰C to avoid any deformation to the metal castings at the time of breaking of mould.

6. Which of the following processes is known as fettling?

a) Cleaning of castings

b) Pouring of melt into mould

c) Releasing of gases from the melt

d) Inclusion of slag in the castings

Answer: a

Explanation: The complete process of the cleaning of castings, called fettling, involves the removal of the cores, gates and risers, cleaning of the casting surface and chipping of any of the unnecessary projections on surfaces with the help of either hand tools or pneumatic tools.

7. Flame or arc cutting method is used for the removal of dry sand cores from the castings.

a) True

b) False

Answer: b

Explanation: Flame or arc cutting method is used for the removal of gates and risers from the castings. The dry sand cores can be removed simply by knocking off with an iron bar, by using a core vibrator, or by means of hydro-blasting. The method depends on the size, complexity and the core material used.

8. Which of the following methods is more convenient for the removal of very large size gates and risers from the steel castings?

a) Hammering

b) Chipping

c) Flame or arc cutting

d) Hack sawing

Answer: c

Explanation: For steel and other similar materials, sawing with any metal cutting saw like a hack saw or band saw would be convenient, But for large size gates and risers, it may be necessary to use flame or arc cutting to remove them. Similarly, abrasive cutoff may also be used for the removal of gates.

9. A reduced metal section at the casting joint makes easy removal of gates and risers from the castings.

a) True

b) False

Answer: a

Explanation: Removal of gates and risers can be simplified by providing a reduced metal section at the casting joint, so for brittle materials such as grey cast iron, the gates can easily be broken by hitting with a hammer. The gates and risers can be removed by hammering, chipping, hack sawing, abrasive cutoff etc.

10. Which of the following techniques is used for smoothening of the rough cut gate edges on the castings?

a) Hack sawing

b) Flame cutting

c) Sand blasting

d) Pedestal or swing frame grinding

Answer: d

Explanation: The casting surface after removal of gates contain some rough surfaces left at the time of removal of gates, or some fins and other projections on the surface near the parting line. These rough cut gate edges can be smoothened by using either the pedestal or swing frame grinder depending on the size of the casting.

11. Which of the following methods is best for cleaning of sand particles sticking to the casting surface?

a) Chipping

b) Sand blasting

c) Grinding

d) Hammering

Answer: b

Explanation: For cleaning the sand particles sticking to the casting surface, sand blasting is used. The casting is kept in a closed box and a jet of compressed air with a blast of sand grains or steel grit is directed against the casting surface, which thoroughly cleans the casting surface.

12. Tumbling method, for cleaning of sand and unwanted fins from the castings, can be used for thin castings with fragile or overhung segments.

a) True

b) False

Answer: b

Explanation: In the tumbling method, the castings are kept in a barrel which is completely closed and then rotated on a horizontal axis at 30-40 rpm. Movement of casting removes the sand and unwanted fins. However, one precaution to be taken for tumbling is that the castings should be rigid with no frail or overhung segments, which may get knocked off during the tumbling operation.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Product Design for Sand Castings”.

1. In designing for economical moulding, it is not advisable to have complexities in the parting line.

a) True

b) False

Answer: a

Explanation: Parting line is determined by the shape of the casting. The simplest parting line is that running through the centre line of the casting as shown in the below figure. Unnecessary complexities in the parting line increase the cost. So the designer strives to design castings with parting planes that are straight or as nearly straight as possible.

casting-questions-answers-product-design-sand-castings-q1

2. Analysis of variations in the foundry procedures has no affect on the economy of production.

a) True

b) False

Answer: b

Explanation: Economy of production is a very important factor. Variations in the foundry procedures, in the form of patterns and core boxes, are thoroughly investigated to ensure the most economical plan for producing castings of specific quality. Furthermore, operations apart from those of pattern shop and foundry are also considered to have economical plan.

3. In sand castings, modification of bosses is done to_____

a) have good surface finish

b) to reduce the chances of porosity

c) to eliminate the use of core

d) to reduce casting yield

Answer: c

Explanation: Bosses are mainly used to increase the sectional thickness of the housing in order to improve the strength of certain parts of casting. The modified boss or the extension of a boss to the flange eliminates the need of a core and also the undercut, which forms a less complicated design.

4. The axis of the cylindrical boss should be in the parting plane to have satisfactorily use of boss in casting.

a) True

b) False

Answer: a

Explanation: Bosses are frequently used in order to provide longer bolt or tap holes in certain parts of the casting, this may be cast satisfactorily if the axis of the cylindrical boss is parallel to the direction in which the pattern is drawn out from the mould or if the centerline of the boss is in the parting plane.

5. Contours, cavities and passages in the casting can be possible without placing of any cores in the casting.

a) True

b) False

Answer: a

Explanation: In the normal moulding, it is not possible to have any contours, cavities and passages in the casting. Cores are placed in the mould to achieve the required passages in the casting. But, a minor change in the design of casting can achieve this and also economize production cost, by eliminating cores.

6. In the solidification process, external angles have a lower cooling rate than re-entrant angles of the casting.

a) True

b) False

Answer: b

Explanation: Solidification progresses from thin to thick sections and external angles have a greater cooling rate than re-entrant angles; the reason being that sand around a re-entrant angle is surrounded on two sides by the heat sources. And re-entrant angle should be made proper to avoid cracks which often begin at the shrinkage cavities.

7. Non-uniform cross-sectional areas of the high temperature casting lead to having hot spots in the casting.

a) True

b) False

Answer: a

Explanation: In a casting of uniform width and thickness, no temperature variations would exist throughout the length of the casting. However, if the casting has non-uniform cross-sectional areas, the temperature would vary considerably. And a high temperature position is called as the hot spot, as shown in below figure. casting-questions-answers-product-design-sand-castings-q7

8. Positive temperature gradient which gradually increases towards the feed head, avoid shrinkage defects.

a) True

b) False

Answer: a

Explanation: Redesign is the most effective way to avoid shrinkage defects. The designer tries to place and proportion members and their intersections in such a way as to establish a positive temperature gradient which is lowest at points farthest away from the feed head and which gradually increases towards the feed head.

9. Which of the following methods is used to detect a concentration of the metal?

a) Check triangle method

b) Euler’s method

c) Finn’s method

d) Check circle method

Answer: d

Explanation: The check circle method is normally used for detecting the concentration of the metal to avoid the shrinkage problems which particularly severe in junctions by reducing the concentration of metal at joints. A concentration of metal always occurs at the point where two walls of equal thickness come together.

10. What should be the ratio of rib thickness to wall thickness in castings for proper avoiding of concentration of metal at joints?

a) 1 to 2

b) >2

c) >1

d) 0.6 to 0.8

Answer: d

Explanation: Rib thickness/Wall thickness = 0.6 to 0.8, When the concentration is reduced, one of the walls is made thinner as shown in below figure. That is why for castings, ribs are always made thinner than the wall in the ratio, to avoid the concentration of metal at joints. casting-questions-answers-product-design-sand-castings-q10

11. Cooling of casting walls of non uniform thickness results into formation of tears or warping in the metal casting.

a) True

b) False

Answer: a

Explanation: If the casting walls have non-uniform thicknesses, then the thinner walls would have cooled down very quickly leaving the thicker wall still in the plastic state. When the thinner walls contract due to solid shrinkage, because of the plasticity, the thicker rib would warp.

12. The formation of hot tears in the hand wheels or big gear wheels can be reduced by_____

a) making the hub of greater strength

b) reducing the thickness of the spokes

c) increasing the ductility of the spokes

d) increasing the thickness of the spokes

Answer: c

Explanation: By increasing the ductility of the spokes, it is possible to reduce the formation of hot tears in the hand wheels or big gear wheels. The ductility can be increased by making the spokes curved and having them in odd numbers. The odd number of spokes ensures that the restraining force acts in only one direction making the wheel more ductile.

13. Which of the following is not desirable in casting design for minimum stress concentration?

a) Roundness of external corners

b) Local metal accumulations

c) No abrupt changes in casting walls

d) Uniform thickness of casting walls

Answer: b

Explanation: In casting design for minimum stress concentration and good casting consistency, local metal accumulations and massive elements should be avoided as much as possible to restrict the generations of shrinkage defects in the castings, which can also be caused by having of low strength of casting at a higher temperature.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Special Casting Techniques”.

1. Which type of sand is used in shell moulding?

a) Black sand

b) Wet and fine sand

c) Dry and fine sand

d) Any of the sand

Answer: c

Explanation: Dry and fine sans is used in shell moulding. It is completely free if clay .

2. Which is the most widely used resin in shell moulding?

a) Phenol formaldehyde

b) Ethanol formaldehyde

c) Phenol

d) Ethanol

Answer: a

Explanation: Phenol formaldehyde is used as resin in shell moulding. It acts like a thermoplastic material.

3. The machine used to mix shell mould particles consistently is __________

a) Mixer

b) Cupola furnace

c) Mueller

d) Mixer & Cupola furnace

Answer: c

Explanation: Mueller is the machine used to mix mould particles thoroughly.

4. Which of the following statement is true?

a) The size of the casting can be adjustable

b) The size of the casting is not limited

c) The size of the casting obtained by shell moulding is limited

d) None of the mentioned

Answer: c

Explanation: The size of the casting is limited and is usually up to 200kg.

5. Cylinder and cylinder heads for air cooled IC engines are casted using which technique?

a) Precision investment casting

b) Shell moulding

c) Permanent mould casting

d) Die casting

Answer: b

Explanation: Cylinders, cylinder head, automation parts, cast tooth etc are casted using shell moulding.

6. In precision investment casting, to make the mould the prepared pattern is dipped into a slurry. From which material is this slurry is made up of?

a) Ethyl silicate

b) Sodium silicate

c) Both Ethyl and Sodium silicate

d) Neither Ethyl nor Sodium silicate

Answer: c

Explanation: The slurry in which prepared pattern is dipped into is made by suspending fine ceramic particles in ethyl silicate or sodium silicate.

7. Cores used in PMC are usually made up of?

a) Metal

b) Collapsable material

c) Sand

d) All of the mentioned

Answer: d

Explanation: In PMC the cores can be made out of any of these materials.

8. Another name of Gravity Die Casting is?

a) Centrifugal casting

b) Permanent mould casting

c) Precision investment casting

d) Hot chamber process

Answer: b

Explanation: Since, metal enters the mould under gravity, hence permanent, mould casting is also known as gravity die casting.

9. In PIC, any wax remnants are dissolved with the help of hot vapors of a solvent. Which solvent is used for this purpose?

a) Ethanol

b) ChloroFluoroCarbon

c) TriChloroEthylene

d) Any of the above

Answer: c

Explanation: Before preheating of the prepared mould, any of the wax remnants are dissolved with the help of a solvent such as TriChloroEthylene.

10. Which of the following is a limitation of die casting, but is overcome in vacuum die casting?

a) The air left in the cavity when the die is closed

b) The moisture left in the cavity when the die is closed

c) The air left in the cavity when the die is open

d) The moisture left in the cavity when the die is open

Answer: a

Explanation: In die casting the major problem is the air left inside the cavity when the die is closed, but in the case of vacuum die casting this air is evacuated out.

11. Pattern used in shell moulding is normally made up of?

a) Wax

b) Metal

c) Wood

d) Plastic

Answer: b

Explanation: Metal is the most used material to make patterns for a process of shell moulding.

12. The casting process that does not require a core to produce a hollow casting is?

a) Shell moulding

b) Hot-chamber die casting

c) Permanent mould casting

d) True centrifugal casting

Answer: c

Explanation: Permanent mould casting is the only process that does not require cores to be used for hollow projections.

13. Hollow casting is the other name of which of the following special casting process?

a) Slush casting

b) Vacuum die casting

c) Precision investment casting

d) Squeeze casting

Answer: a

Explanation: Slush casting is used to make casting which is actually hollow projections. Hence, it is also called a hollow casting.

14. Squeeze casting method was developed in which country?

a) Japan

b) India

c) America

d) Russia

Answer: d

Explanation: Russia was the country in which squeeze casting was first developed.

15. The tundish is a _______

a) Pouring vessel

b) Riser

c) Type of core

d) Machine name

Answer: a

Explanation: Tundish is a refractory lined intermediate pouring vessel.

16. Which of the type of centrifugal casting methods is used to produce ‘non-symmetrical’ shaped castings?

a) True centrifugal casting

b) Semi centrifugal casting

c) Centrifuging

d) Non centrifugal casting

Answer: c

Explanation: More than a single object is connected radially through a central sprue in centrifuging. But the castings need not be symmetrical always, unlike other centrifugal casting processes.

17. True centrifugal casting method is usually used to make __________

a) Bent pipes

b) Hollow pipes

c) Bolts

d) Nuts

Answer: b

Explanation: True centrifugal casting method is usually used to make ‘hollow pipes and tubes’.

18. Pressure range for low pressure die casting is ___________

a) 0.3-1.5 bars

b) 0.5-2 bars

c) 2-6 bars

d) up to 8 bars

Answer: a

Explanation: Usually the gauge is set to a range of 0.3-1.5 bars while providing pressure to the molten metal to raise it in the riser.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Shell Moulding”.

1. Which of the following synthetic resins are used for mixing with sand in shell moulding?

a) Thermosetting resins

b) Epoxy resins

c) Fiber glass resins

d) Kevlar

Answer: a

Explanation: The synthetic resins used in shell moulding are essentially thermosetting resins, which get hardened by heat. Phenol formaldehyde resins are mostly used, which combines with sand to form a proper mixture for shell moulding. The mixture formed has high strength and resistance to heat.

2. Grain size of the sand particles has no affects on the surface finish of the casting.

a) True

b) False

Answer: b

Explanation: Generally, for the preparation of shell moulding sand, dry and fine sand that is completely free of the clay is used. The grain size to be chosen depends on the surface finish required on the casting. Too much fine a grain size requires a large amount of resin, which makes the mould expensive.

3. In shell moulding sand preparation, the resin is combined with a catalyst  to develop the_____

a) thermoplastic characteristics

b) toughness of the resin

c) thermosetting characteristics

d) viscosity of the resin

Answer: c

Explanation: The phenolic resins used in shell moulding have excess of phenol and acts like a thermoplastic material. During coating with sand the resin is mixed with a catalyst such as hexa methylene tetramine  in a proportion of 14 to 16 % so as to develop the thermosetting characteristics.

4. Which of the following compositions of the shell sand is used for avoiding of thermal crack during pouring?

a) Silica sand

b) Zircon sand

c) Resin

d) Additives

Answer: d

Explanation: Generally, additives are added to the sand mixture to improve the surface finish and also for the avoiding of any thermal crack during pouring. Some of the additives used are coal dust, manganese dioxide, calcium carbonate, pulverized slag and ammonium boroflouride.

5. Which of the following lubricants is added to the resin sand mixture for better flowability of the sand?

a) Lead stearate

b) Magnesium stearate

c) Sulphur stearate

d) Zinc stearate

Answer: d

Explanation: Some lubricants such as zinc stearate and calcium stearate are added to the resin sand mixture to improve the flowability of the sand, which helps in covering of maximum part of the metallic pattern efficiently and also permit easy release of the shell from the pattern.

6. Which of the following devices is used for the mixing or complete formation of the shell sand mixture?

a) Chucker

b) Mueller

c) Semi circular roller

d) Semi cylindrical roller

Answer: b

Explanation: Sand, hexa and additives, which are all dry, are mixed inside a Mueller for a period of 1 minute, then the liquid resin is added and mixing is done for another 3 minutes. Then by introducing cold or warm air into the Mueller, mixing is continued till all the liquid is removed from the mixture and coating of the grains is achieved to the desired degree.

7. Which of the following metals is used for the preparation of patterns in shell moulding?

a) Aluminium

b) Copper

c) Grey cast iron

d) Brass

Answer: c

Explanation: Generally, metal patterns with the associated gating are used. The metal used for preparing patterns is grey cast iron; it is mainly used because of its easy availability and good stability at the temperatures involved in the process. Sometimes, additional risers are also required as the cooling in shell moulds is slow.

8. Which of the following devices is used for the formation of shell mould in the shell moulding procedure?

a) Air roller

b) Re-circulating ball roller

c) Chucker

d) Dump box

Answer: d

Explanation: A silicone release agent is sprayed on the heated metallic pattern which is fixed to a dump box, wherein the coated sand of sufficient amount is filled in. Then the dump box is rotated so that the coated sand falls on the heated pattern and the heat liberating from the pattern melts the resin and causes sand mixture to adhere to the pattern.

9. At the last of shell moulding procedure, the Dump box is rotated backward for adhering of as much as the possible amount of sand to the metallic pattern.

a) True

b) False

Answer: b

Explanation: When after the achieving of a desired thickness of the shell, the dump box is rotated backward by 180 degrees so that the excess of sand falls back into the box, leaving the formed shell intact with the pattern. Thickness of the shell depends on the temperature of the pattern and the coating time of sand in contact with the heated pattern.

10. Over-curing or under-curing of the shell mould, leads to the generation of sophisticated problems in the shell mould.

a) True

b) False

Answer: a

Explanation: For the curing of the shell mould, it is kept in an electric or gas fired oven. The curing of the shell should be done as per requirements only because over-curing can cause the mould to break down as the resin would burn out. And under-curing may result in blow holes in the casting or the shell may break during handling.

11. There is no need for any external support for the shells at the time of pouring of molten metal.

a) True

b) False

Answer: b

Explanation: Since the shells are thin, and pouring of molten metal into the shells may cause an imbalance which further leads to failure of the castings. So to avoid this, it may require some outside support to withstand the pressure of the molten metal and to form the castings efficiently with proper balance.

12. Which of the following types of clamping is mostly performed for the joining of shells?

a) Mechanical

b) Electrical

c) Pneumatic

d) Hydraulic

Answer: a

Explanation: The prepared shells are joined together by mechanical clamping or sometimes adhesive bonding is also preferred for joining of shells. The resin used as an adhesive may be applied at the parting plane before mechanical clamping and then allowed for 20 to 40 seconds to achieve necessary bonding. Then the shell mould becomes ready for pouring of molten metal.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Precision Investment Casting”.

1. Which of the following is used as the pattern material in precision investment casting?

a) Metal

b) Molten wax

c) Plastic

d) Wood

Answer: b

Explanation: An expendable pattern, around which the mould is prepared. For the preparation of the pattern for every casting to be made, molten wax is used as the pattern material, which is injected under pressure of about 2.5 MPa into a metallic die, which has the cavity of the casting to be made. After the solidification of wax, it would produce the pattern.

2. Which of the following liquids is used for the formation of slurry in investment casting?

a) Ammonium hydroxide

b) Carbon disulfide

c) Sodium silicate

d) Glycerin

Answer: c

Explanation: To make the mould, the prepared pattern is dipped into slurry made by suspending fine ceramic materials in a liquid called sodium silicate or sometimes another liquid ethyl silicate is also used for the preparation of slurry. The excess liquid is allowed to drain off from the pattern to have an appropriate thickness of the mould.

3. The process of dipping and stuccoing is performed continuously to achieve the desired thickness of the mould in the investment casting.

a) True

b) False

Answer: a

Explanation: In the process of stuccoing, dry refractory grains such as zircon or silica are stuccoed on the liquid ceramic coating. A small shell is formed around the pattern, which is to be cured and then the process of dipping and stuccoing is continued with ceramic slurries to achieve a well desired thickness of the mould.

4. Molten metal is poured into the mould; meanwhile it removes the wax by melting it and vapourization of wax takes place simultaneously in the investment casting.

a) True

b) False

Answer: b

Explanation: Firstly the pattern is removed completely from the mould then the process of pouring of molten metal occurs in the investment casting. For the removal of pattern from the mould, heating is done to melt the pattern. Then the melted wax is completely drained through the sprue by inverting the mould.

5. Which of the following materials takes part in the removal of remnants wax from the mould?

a) Nitroglycerin

b) Phosphoric acid

c) Water

d) Trichloro-ethylene

Answer: d

Explanation: After the removal of wax by melting and inverting the mould, some particles of the wax still stucked at the inside corners of the mould, and removal of them is very necessary to have castings free from defects. So, hot vapours of trichloro-ethylene are dissolved with the wax remnants in the mould to remove the same.

6. Pre-heating of the mould is done to generate adhering characteristics of the moulding surface.

a) True

b) False

Answer: b

Explanation: The moulds are pre-heated to a temperature of 100 to 1000 ⁰C, depending on the complexity, size and the metal of the casting. This is mainly done to reduce any last traces of wax left off and permit proper filling of all mould sections, which are too thin to be filled in a cold mould.

7. Investment casting is not suitable for producing complex shapes of castings.

a) True

b) False

Answer: b

Explanation: Complex shapes which are difficult to produce by any other method are possible in the precision investment castings since the pattern is withdrawn by melting it. And the thin sections with complexities can also be produced because the mould is heated before pouring of molten metal.

8. If mercury is used as a pattern material in place of wax, then for the preparation of mould, mercury is kept at temperature_____

a) below -38 ⁰C

b) 0 ⁰C

c) 0 to 38 ⁰C

d) -38 to 0 ⁰C

Answer: a

Explanation: If mercury is used as a pattern material in place of wax, then the process is known as mercast, the mercury is kept under -57 ⁰C where the mercury is frozen. And the complete mould preparation is to be undertaken at a temperature below -38 ⁰C to keep the mercury in solid state.

9. Which of the following is the main problem or disadvantage of using mercury as a pattern material?

a) Variation in density of pattern

b) Less formability

c) Keeping of pattern at too low temperature

d) Less strength

Answer: c

Explanation: When the mercury is used in place of wax as a pattern material, it has an advantage that it does not expand when changed from solid to liquid state as wax. But the main disadvantage or drawback is keeping the pattern at such low temperature, which is mainly responsible for its less useful.

10. Castings produced by investment casting do not require any further machining for finishing of the surface.

a) True

b) False

Answer: a

Explanation: As control of grain size and its orientation is possible in investment castings, so it makes the casting ready for use without any requirement of machining. This is particularly useful for those hard to machine materials such as nimonic alloys. So this process saves time and money both, which is usually spent on machining for other processes.

11. Investment casting is a cheap process with no limits on size and mass of the casting.

a) True

b) False

Answer: b

Explanation: Investment casting is a very expensive process for producing castings because of larger manual labour involved in the preparation of the pattern and the mould. And this process is also limited by the size and mass of the casting. The maximum limit on the mass of casting may be of the order of 5 kg.

12. Which of the following products is mostly produced by precision investment casting?

a) Aluminium billets

b) Rail

c) Connecting rod and crankshaft

d) Jewellery and surgical instruments

Answer: d

Explanation: As in investment casting, less mass and size of casting with high complexities can be produced easily. So the jewellery and surgical instruments are produced easily in the investment casting. Other products like vanes and blades for a gas turbine, shuttle eyes for weaving, wave guide for radars and impellers for turbo chargers can also be produced.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Permanent Mould Casting”.

1. Which of the following is the main purpose of using permanent mould casting?

a) Variety in production

b) Production of castings with complexities

c) Large scale production

d) Production of highly expensive castings

Answer: c

Explanation: Making a mould for every casting to be produced may be difficult and expensive for the large scale production. Therefore, a permanent mould, called die may be made from which a large number of castings, anywhere between 100 to 250,000 can be produced easily, depending on the complexity and alloy used for the casting.

2. In permanent mould casting, only the metallic type of cores can be used, as the mould material used is also metallic.

a) True

b) False

Answer: b

Explanation: Cores are used in permanent mould casting for making any hollow portions in the casting. The cores can be made out of metal or sand also when sand cores are used in the casting, the process is called semi-permanent moulding. The sand core of complex shapes can be used with undercuts easily in the casting.

3. For complicated shapes, it is better to use collapsible metal cores rather than a single metal core in the casting.

a) True

b) False

Answer: a

Explanation: It is difficult to securely position the metallic core as a single piece due to the dimensional variations that are likely to occur. So the collapsible metal cores  are sometimes used in permanent moulds, but the designer has to provide coarse tolerance on the dimensions.

4. Metallic core is more preferable than the sand core in the permanent mould casting.

a) True

b) False

Answer: b

Explanation: Metallic core is not preferable that the sand core, because the metallic core cannot be complex with undercuts and the like. Also, the metallic core is to be withdrawn immediately after solidification; otherwise, its extraction becomes very difficult because of its shrinkage.

5. Experiment with gating systems in sand casting is performed before the construction of gating systems for the metallic mould.

a) True

b) False

Answer: a

Explanation: The gating and risering systems used in the permanent mould casting are very similar to that of the sand casting. In fact, to get the proper gating arrangement, it is desirable first to experiment with various gating systems in sand casting and then finally arrive at the correct gating system for the metallic mould.

6. It is desirable to have drafts or undercuts as much as possible in the mould cavity, to have greater strength of the castings.

a) True

b) False

Answer: b

Explanation: The mould cavity should be simple without any undesirable drafts or undercuts because these interfere with the ejection of the solidified castings and makes the casting weak and less durable. And care should be taken to see that progressive solidification occurs toward the riser, in the designing of permanent moulds.

7. Which of the following is not the function of coating of refractory materials on the mould?

a) Prevent the soldering of metal to the mould

b) Minimize thermal shock to the mould

c) Control the rate of casting solidification

d) Increase the heat transfer rate

Answer: d

Explanation: The moulds are coated with a refractory material to increase the mould life by preventing the soldering of metal to the mould, by controlling the direction and rate of the casting solidification and also by minimizing the thermal shock to the moulding material. Coatings can be a mixture of sodium silicate, clay, soap, stone, talc etc.

8. What should be the maximum desirable thickness of the coatings applied to the mould?

a) 0.8 mm

b) 2 mm

c) 5 mm

d) 10 mm

Answer: a

Explanation: The main requirement of a coating is that it should be inert to the casting alloy. The coating can be applied by brushing or spraying. It should be thick enough to fill up any surface imperfections. Generally, the maximum desirable thickness of a coating of refractory material is about 0.8 mm.

9. The coating is applied thicker at surfaces, where the faster cooling rate is required.

a) True

b) False

Answer: b

Explanation: The coatings can be both of insulating type and lubricating type. The coatings can be applied thicker at surfaces, which need to be cooled slowly, for example, sprues, risers, thin sections and runners. More the thickness of the coatings less will be the heat transfer rate from the castings.

10. In permanent mould casting, the temperature at which the mould is used does not depend on _____

a) casting weight

b) casting wall thickness

c) pressure in casting

d) pouring temperature

Answer: c

Explanation: Under the regular casting cycle, the temperature at which the mould is used depends on the casting weight, casting shape, casting cycle frequency, pouring temperature, wall thickness of the castings, wall thickness of the mould and the thickness of the mould coating.

11. In permanent mould casting, the mould is pre-heated to its operating temperature before the actual use of mould.

a) True

b) False

Answer: a

Explanation: When the casting is done with the cold die, the first few castings are likely to have misruns  till the die reaches its operating temperature. To avoid this, the mould must be pre-heated to its operating temperature, preferably in an oven.

12. Permanent mould casting is suited to low volume production of moderate or complex shapes of casting.

a) True

b) False

Answer: b

Explanation: To economize the use of metallic mould, the permanent mould casting is particularly suited to high volume production of simple, small castings with uniform wall thickness and no intricate details. The materials which are cast in permanent moulds are zinc alloys, copper alloys, magnesium alloys, grey cast iron etc.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Die Casting”.

1. Which of the following considerations distinguish die casting from the permanent mould casting?

a) Moulding material

b) Way of pouring molten metal

c) Coating on mould

d) Size of castings

Answer: b

Explanation: Die casting is almost the same as permanent mould casting, in that both the processes use reusable metallic dies. Die casting involves the preparation of components by injecting molten metal at high pressure into a metallic die; this way of pouring of molten metal distinguishes die casting from the permanent mould casting.

2. It is easy to produce any complex shapes and narrow sections in the die casting.

a) True

b) False

Answer: a

Explanation: In die casting, as the metal is forced in under pressure compared to the permanent mould casting, it is also known as pressure die casting. Because of involvement of high pressure in die casting, any type of complex shapes, narrow sections and fine surface details can easily be produced.

3. Due to the presence of ejector die, there is no need of lubricant for the removal of casting from the dies.

a) True

b) False

Answer: b

Explanation: For the easy removal of casting from the dies, lubricant is required. The lubricant is sprayed on the die cavity manually or by the auto lubrication system so that the casting will not stick to the die. Ejector die only moves out itself for the extraction of the castings, but the lubricant is essential for the easy removal of the castings.

4. A single piece or unitary part of the metallic die is used for making castings in die casting.

a) True

b) False

Answer: b

Explanation: Die casting mainly has two parts. One part is the stationary half or cover die, which is fixed to the die casting machine. The second part is the moving part or ejector die that is moved out for the extraction of the casting. The casting cycle basically starts when the two parts of the die are apart.

5. Which of the following ways of cooling is used for the maintaining of die temperature?

a) Natural air cooling

b) Forced air cooling

c) Water channels cooling

d) Liquid nitrogen cooling

Answer: c

Explanation: As the metallic die is used in the die casting as a mould, so the extraction of heat from the molten metal will not be easy. So for maintaining proper die temperature, water cooling channels are used near the castings through the cover and ejector die. This makes the proper solidification of the castings.

6. In cold chamber die casting, rapid cooling of the castings is done as compared to the hot chamber die casting.

a) True

b) False

Answer: b

Explanation: In hot chamber die casting, the holding furnace for the liquid metal is integral with the die casting machine, whereas in cold chamber die casting, the metal is melted in separate furnace and then poured into the die casting machine with the help of a ladle for each casting cycle which is also called shot.

7. In the hot chamber die casting process, which of the following parts is used for the pumping of liquid metal into the cavity?

a) Accumulator

b) Slug

c) Guide pin

d) Gooseneck

Answer: d

Explanation: A gooseneck is used for the pumping of liquid metal into the die cavity. It is made of ductile iron or of cast steel. The gooseneck is submerged in the holding furnace containing the molten metal. Then a plunger which is hydraulically operated moves up in the gooseneck to open the entry port for the entry of liquid metal into the gooseneck.

8. In hot chamber die casting processes, downward motion of plunger in the gooseneck leads to injection of molten metal into the cavity with high pressure.

a) True

b) False

Answer: a

Explanation: In the gooseneck, the highest position of the plunger facilitates the filling of the gooseneck by the liquid metal. Then the plunger starts moving down to force the metal in the gooseneck to be injected into the die cavity. The metal is then held at the same temperature till it is solidified.

9. In hot chamber die casting, the plunger is also used for taking back of unused molten metal to the gooseneck after the fulfilling of the cavity.

a) True

b) False

Answer: a

Explanation: After the filling of molten metal into the cavity, somewhat of melt still remains in the nozzle or sprue part. To avoid the wastage of melt, plunger is used, which by moving back returns the unused liquid metal to the gooseneck. This process saves a lot of molten metal and hence economizes the production.

10. Which of the following materials is not suitable to be cast by a hot chamber die casting process?

a) Lead

b) Tin

c) Aluminium

d) Zinc

Answer: c

Explanation: The hot chamber die casting process is basically used for the low melting temperature alloys. But, for material such as aluminum, its high melting temperature makes it difficult to cast by hot chamber die casting process, because continuous contact of gooseneck with the molten metal can destroy the gooseneck material.

11. Using of the ladle in the cold chamber die casting has no affects on contact time between the molten metal and the shot chamber.

a) True

b) False

Answer: b

Explanation: When the molten metal is ladled into the shot chamber of the machine either manually by a hand ladle or by an auto ladle, which is a form of a robotic device. This process reduces the contact time between the molten metal and the shot chamber, so the high melting temperature materials can be cast easily.

12. The chances of defects in the castings by cold chamber die casting are more than the castings produced by hot chamber die casting.

a) True

b) False

Answer: a

Explanation: Since the metal is ladled into the machine from the furnace, so it may lose the superheat and may cause defects in the castings such as cold shuts. Also, there is a main disadvantage in the cold chamber die casting process is the longer cycle time needed as compared to the hot chamber die casting process.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Gravity Die Casting”.

1. Which of the following show can the approximate number of castings be produced by gravity die casting?

a) 0-50

b) 50-100

c) 100-250,000

d) 250,000-500,000

Answer: c

Explanation: As a reusable metallic die is used as a mould that is beneficial for large scale production. A large number of castings around 100-250,000 can be produced easily without any in-between maintenance, to achieve more no. of castings sometimes repairing is required to remove any distortion if produced in the mould.

2. Gravity die casting is best suited for highly viscous molten metal and for producing the complex shape of castings.

a) True

b) False

Answer: b

Explanation: In gravity die casting, liquid metal enters into the cavity by means of gravity force only, as shown in below figure. It is used to produce a simple shape of the objects made up of high fluidity materials. And due to fast rate of cooling, fine gain structure will be developed in the castings which are having more strength and hardness. casting-questions-answers-gravity-die-casting-q2

3. Which of the following considerations is independent for the selection of moulding material?

a) Size of the casting

b) Frequency of casting cycle

c) Pouring temperature

d) Fluidity of pouring melt

Answer: d

Explanation: The mould material is basically selected on the considerations of the size of the casting, pouring temperature and the frequency of the casting cycle, which all together determine the total heat to be borne by the die. Fluidity of the pouring melt can be dependent on the shape of mould, but it is totally independent for the selection of moulding material.

4. Which of the following materials is mostly used as a die material in gravity die casting?

a) Grey cast iron

b) Lead

c) Magnesium

d) Aluminium

Answer: a

Explanation: In gravity die casting, fine-grained grey cast iron is the most generally used die material. Sometimes alloy cast iron, alloy steels  and C20 steel are also used as die material for very large volumes and large parts. For small volume production of aluminium and magnesium, mould made of graphite is preferred.

5. The die life is less for higher melting temperature alloys in gravity die casting.

a) True

b) False

Answer: a

Explanation: The die life is less for higher melting temperature alloys such as copper and grey cast iron. Very high temperature of molten metal in contact with the moulding surface damages it and may cause surface erosion. This can be avoided by using die material of highly resistant to the temperature of molten metal.

6. Continuous extraction of heat is necessary to ensure higher mould life and better casting cycle times.

a) True

b) False

Answer: a

Explanation: A large amount of heat will be absorbed by the mould material as the metallic mould would be used. So for the continuous extraction of heat, it is important to make provision in the construction of the mould. This is mainly done to increase mould life and to have better casting cycle times.

7. Air cooling is sufficient to maintain temperature for the large and thick-walled castings in gravity die casting.

a) True

b) False

Answer: b

Explanation: Air cooling is not sufficient except for thin and small castings. Generally, air cooled dies are provided with fins on the outer surfaces to increase the heat extraction. And cooling water can be also circulated through the portions of the mould that are likely to have large heat concentration.

8. Water cooling is always preferred than the air cooling for the extraction of heat from the castings through the mould.

a) True

b) False

Answer: b

Explanation: It is true that water cooling results into higher extraction of heat from the castings, but its application arises some problems. The likely problems with the cooling water circulation are the formation of scales inside the cooling channels and their subsequent blocking after some use. That’s why sometimes water cooling is less preferred than the air cooling.

9. If the heavy casting is produced, then which of the following can be used to maintain the progressive solidification?

a) Sprue

b) Riser

c) Chills

d) Pouring basin

Answer: c

Explanation: When the heavy sections of casting are made then they are likely to interfere with the progressive solidification, this interference can be avoided by using chills supported by heavy air blast to remove excess of heat. Also, the cooling channels can be provided at the necessary points to get proper temperature distribution.

10. Better surface finish with the close dimensional tolerances of the casting can be obtained in gravity die casting.

a) True

b) False

Answer: a

Explanation: In gravity die casting, a fined-grained casting with good surface finish of the order of 4 microns can be produced. Close dimensional tolerances can also be obtained and with a better appearance of the casting. It is also economical for large scale production as the labour involved in the mould preparation is reduced.

11. All kind of metals can be cast easily in the gravity die casting.

a) True

b) False

Answer: b

Explanation: Not all materials can be casted easily by gravity die casting essentially because of the mould material. The problem of sticking arises due to the application of metallic mould; so much of lubricant is required, still cannot be suited for every metal. This casting method is applicable to some metals only.

12. Which of the following processes is most suitable for the casting of connecting rods and pistons of the automobile?

a) Precision investment casting

b) Gravity die casting

c) Shell moulding

d) Centrifugal casting

Answer: b

Explanation: As a simple shape of the casting can be produced by gravity die casting, so conventionally gravity die casting is best suited for casting connecting rods and pistons of the automobile. Many other components like stators, gear blanks, aircraft fittings etc. can also be produced easily by gravity die casting.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Vacuum Die Casting”.

1. Which of the following problems arises in die casting that can be solved by having vacuum die casting?

a) Overheating

b) Interruption in progressive solidification

c) Air in the cavity

d) Difficulty in cooling of casting

Answer: c

Explanation: The major problem with die casting is the air left in the cavity after closing of die. Since the air cannot escape out so it remains inside the casting. This result in the generation of blisters, which basically appears on the surface of the castings, when the casting is heat treated. This problem can be solved by implementing a vacuum die casting method.

2. In vacuum die casting, the molten metal does not experience any back pressure while injecting it into the die cavity.

a) True

b) False

Answer: a

Explanation: In vacuum die casting, before the injection of molten metal, all the air presents in the die cavity is evacuated and then the die is closed. So by performing this operation, the molten metal does not experience any back pressure while injecting it into the die cavity, this makes the process easier.

3. In vacuum die casting, the molten metal enters into the cavity slowly as compared to the die casting.

a) True

b) False

Answer: b

Explanation: The removal of all the gases from the die cavity makes a vacuum inside the cavity, so there is no pressure or force inside the cavity which could be opposite to the injecting pressure of the molten metal. So, the molten metal enters much faster into the die, thereby decreasing the fill time.

4. The castings made by vacuum die casting have more strength than the castings made by die casting.

a) True

b) False

Answer: a

Explanation: In vacuum die casting, the components which are casted do not experience any porosity due to the removal of all the air from the cavity. The castings made have negligible porosity as compared to the castings made by die casting. So, the castings are of high strength in the vacuum die casting.

5. Which of the following helps in reducing the oxidation of the material in vacuum die casting?

a) Mould thickness

b) Mould material

c) Tight tolerances

d) Mould coating

Answer: c

Explanation: In vacuum die casting, the part is exposed to atmospheric air only after solidification, and oxidation of the material is avoided as much as possible. This can be achieved by processing of parts with tight tolerances and also by faster cooling rate which results into fine microstructure nature of castings.

6. Rapid solidification rates of casting tend to have a reduction in oxidation of the material.

a) True

b) False

Answer: a

Explanation: Rapid solidification rates of the casting can avoid the oxidation of the material in the vacuum die casting . This is accomplished by providing very thin walls  of mould to the casting with close tolerances. Then the properties of casting approach to that of wrought product, and with relatively short cycle times.

7. Which of the following helps in removing of casting from the ejector die?

a) Tie bar

b) Plunger

c) Platen

d) Ejector pins

Answer: d

Explanation: The ejector pins, which move through the moving die to free the casting from the ejector die. The number of ejector pins should be sufficient so as to remove the hot casting without any distortion. And the position of ejector pins should be like so that the pins marks remain on the casting are not objectionable.

8. The moving cores are used in the vacuum die casting, which are parallel to the movement of a die.

a) True

b) False

Answer: b

Explanation: Fixed cores and moving cores, both of metal are used in this method of casting. Moving cores are not parallel with the die movement and hence are to be removed before the casting is ejected from the die. And other is fixed cores, which are fixed to the die halves and parallel to the die movement.

9. Which of the following parts is fixed to the stationary platen of the casting machine?

a) Cover die

b) Ejector die

c) Sprue

d) Runner

Answer: a

Explanation: Mainly two parts of the casting machine, one is a cover die which is fixed to the stationary platen and another one is ejector die which is fixed to the moving platen of the casting machine. Cover die also makes contact with the nozzle of gooseneck or with the shot chamber in the casting machine.

10. Which of the following is used to remove the metal defect of cold shuts from the casting?

a) Ejector pins

b) Overflows

c) Metal cores

d) Biscuit/Sprue

Answer: b

Explanation: Overflows are basically used for the small components, to provide a sufficient amount of heat to the die material, so that no cold shuts occur in the castings. Also, the overflows can be utilized for the positioning of ejector pins so that no objectionable ejector pin marks appear on the casting.

11. Overflows should be avoided as much as possible in the designing of a die.

a) True

b) False

Answer: a

Explanation: Overflows are provided in the parting plane for the first metal which is usually cold, enters in the die cavity, to solidify. The overflow is a luxury and cannot be acceptable in every casting, so it should be avoided as much as possible in the designing of the die. It is primarily provided for small components only.

12. Short cycle time leads to having a high temperature of the dies in the vacuum die casting.

a) True

b) False

Answer: a

Explanation: If the cycle time is very small, then the dies would readily get heated. Particularly in the sections such as sprues, or heavy sections of the casting, the temperature may be too high. To maintain the required and uniform temperature, water is circulated through the hot regions of the die.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Low Pressure Die Casting”.

1. Which of the following methods of casting is best suited for casting aluminium and magnesium based alloys?

a) Centrifugal casting

b) Low-pressure die casting

c) Shell moulding

d) Investment casting

Answer: b

Explanation: Low-pressure die casting has been adopted generally for the casting of aluminium and magnesium based alloys. Usually a permanent mould or sand moulds are also possible, but this method makes the casting totally free from shrinkage defects and also ensures proper solidification naturally.

2. What should be the pressure range  of the gas used in the low-pressure die casting?

a) 0.3 to 1.5

b) 2 to 10

c) 10 to 30

d) 30 to 50

Answer: a

Explanation: In low-pressure die casting, compressed gas is basically used at a pressure typically ranging from 0.3 to 1.5 bars to force the molten metal to rise slowly through the ceramic riser tube that is connected to the mould. Pressure should be below atmospheric pressure to easily pull the molten metal into the cavity.

3. In low-pressure die casting, mould is placed over the furnace containing the molten metal.

a) True

b) False

Answer: a

Explanation: Low-pressure die casting is not new; some changes are adapted to the permanent mould to generate new characteristics and better properties to the casting. So in this process, the permanent mould and the filling system are placed over the furnace containing the molten alloy in it.

4. The residual molten metal cannot flow back to the crucible and it remains in the riser tube.

a) True

b) False

Answer: b

Explanation: When the mould cavity is filled with molten metal, the pressure in the crucible is removed. This allows the molten metal to flow back to the crucible through the tube. Then after solidification, the sides die opens and the top die is raised vertically. And the casting moves with the top die and ejected onto a transfer tray.

5. Which of the following types of cooling is used for the cooling of top and bottom dies in the low-pressure die casting?

a) Water cooling

b) Liquid nitrogen cooling

c) Cooling with fins

d) Air jets cooling

Answer: d

Explanation: The cooling rate can affect the quality of the casting, so care should be taken to see that the casting is properly cooled before ejecting from the die. For the proper cooling of the top and bottom dies of the casting system, air jets are used which circulated through the dies and takes away the heat.

6. It is not necessary to consider the cooling circuits in designing of mould due to less cycle time.

a) True

b) False

Answer: b

Explanation: Proper cooling is very essential in low-pressure die casting to produce castings of high strength. So, care needs to be exercised during designing of the mould to provide proper cooling circuits, so that the heavier sections of the casting are located close to the feeding path to make it act as a riser.

7. In low-pressure die casting, metal enters the mould very slowly as compared to the die casting.

a) True

b) False

Answer: a

Explanation: In low-pressure die casting, due to the application of riser tube, molten metal flows upward in direction against the gravity. This makes the metal to flow into the mould slowly as compared to the die casting with less turbulence, so the casting quality is also improved by eliminating the defects.

8. Which of the following terms is used for the presence of excess metal in the parting plane?

a) Toggle

b) Platen

c) Flash

d) Biscuit

Answer: c

Explanation: Flash is a term which is used for the excess metal forced into the parting plane. Before using the castings, it is very necessary to remove flash together with any overflow present in the casting. This problem can be solved by implementing low-pressure die casting method, where the condition of excess metal cannot be possible due to upward flow of molten metal.

9. Which of the following products is most suitable to cast by low-pressure die casting method?

a) Crank cases

b) Blades of turbine

c) Surgical instruments

d) Connecting rods

Answer: a

Explanation: Crank cases are very easy to cast by low-pressure die casting, as the upward flow of molten metal reaches to every small corner of the mould and makes the homogenous nature of castings. Many other components like magnetos, handle bar housing and other decorative items of automobile can also be casted by low-pressure die casting method.

10. The die has longer life for casting of materials but less for aluminium alloys.

a) True

b) False

Answer: a

Explanation: As the metallic die is used which has a long life, it is of the order of 300,000 pieces for zinc and similar alloys. But for the aluminium alloys, it is approximately up to the 150,000 pieces of it. The reason is higher melting temperature of aluminium alloys that can destroy the mould with the production of castings.

11. Surface finish of the castings is not better in the low-pressure die casting method as compared to other method of casting.

a) True

b) False

Answer: b

Explanation: Very good surface finish of the order of 1 micron can be obtained in low-pressure die casting method because of application of metallic dies. The surfaces generated by this method of casting can be directly electroplated without any further processing. This method is economical for moderate or large scale production.

12. Low-pressure die casting method is not economical for small-scale production.

a) True

b) False

Answer: a

Explanation: Low-pressure die casting method is not economical for small-scale production because the dies and machines are very expensive, and the other parts like riser tube and the device used for compressing gas make the casting process very expensive. So the economy in production is possible only when large quantities are produced.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Centrifugal Casting”.

1. Which of the following forces provides continuous pressure on the metal in centrifugal casting?

a) Spring force

b) Centrifugal force

c) Gravitational force

d) Frictional force

Answer: b

Explanation: In centrifugal casting, mould is rotated rapidly about its central axis as the metal is poured into it. Because of the centrifugal force, continuous pressure is applied to the metal as it solidifies. The slag and the other inclusions being lighter gets separated from the metal and segregates toward the centre.

2. Which of the following methods of casting is best suited for casting of hollow pipes and tubes?

a) Investment casting

b) Permanent mould casting

c) Die casting

d) Centrifugal casting

Answer: d

Explanation: Specifically, true centrifugal casting is generally used for the making of hollow pipes and tubes, which are axi-symmetric with a concentric hole. Molten metal is accumulated at the inward surface of the mould by the rotation of the mould and then the solidification of a melt is taking place.

3. Special type of sand cores is mainly used for the making of hollow part in the centrifugal casting.

a) True

b) False

Answer: b

Explanation: In centrifugal casting, there is no requirement of any core for the making of the concentric hole. As the metal is always pushed outward because of the centrifugal force, application of core is eliminated. Only the oxides and slag part separate from the metal and segregate at the centre.

4. The axis of rotation of the mould should be horizontal for the casting of long pipes in centrifugal casting.

a) True

b) False

Answer: a

Explanation: In centrifugal casting, the axis of rotation of the mould can be horizontal, vertical or any angle in between. Generally, very long pipes are cast with a horizontal axis, whereas short pieces are more conveniently cast with a vertical axis, as it requires less area for the casting operation.

5. Dry sand cores may be required for the provision of spigot at the end section of the casting.

a) True

b) False

Answer: a

Explanation: When after the proper ramming of sand to confirm to the outer contour of the pipe to be made, dry sand cores may be introduced for the provision of end details such as spigot ends, or flanged ends to the casting. Meanwhile there is no requirement of any cores for the making of the hollow section of the castings.

6. Which of the following parts is provided in between the mould and casing to reduce the vibrations?

a) Steel balls

b) Metallic roller

c) Viscous fluid

d) Grease

Answer: b

Explanation: After the completion of the mould, the flask is balanced dynamically so as to reduce the occurrence of undesirable vibrations during the casting process. And the metallic rollers are used in between the rotating mould and the stationary casing to avoid the jerks and for the damping of vibrations.

7. In centrifugal casting, only sand moulds can be used due to the problem of sticking of metal.

a) True

b) False

Answer: b

Explanation: Not only sand moulds, the metallic moulds can also be used in the centrifugal casting process for large scale production. As inducing of high temperature of metallic mould can be avoided by water circulation through it and sticking problem can also be solved by casting of non-sticking materials.

8. In centrifugal casting, the casting yield is approximately equaled to 100%.

a) True

b) False

Answer: a

Explanation: There is no need for the gates and runners in the centrifugal casting process, which saves a lot of molten metal. This makes the increase in casting yield, reaching almost 100%. And no any application of cores makes the castings very economical for the large scale production.

9. It is also possible to make un-symmetric shape of casting in true centrifugal casting by introducing some variations to the mould.

a) True

b) False

Answer: b

Explanation: It is not possible to make un-symmetric shape of casting in centrifugal casting, only certain shapes which are axi-symmetric and having concentric holes are suitable to make in the centrifugal casting. And equipment are also expensive, so this method is suitable only for large scale production.

10. Castings made by the centrifugal casting process have negligible porosity.

a) True

b) False

Answer: a

Explanation: In centrifugal casting, the inclusions such as slag and oxides get segregated towards the centre and can be easily removed by a machining process. And also the application of pressure on the metal throughout the solidification causes the porosity to be eliminated and gives rise to dense metal.

11. In centrifugal casting, a movable pouring basin is employed for the pouring of molten metal.

a) True

b) False

Answer: a

Explanation: The molten metal is poured into the mould in requisite quantity through a movable pouring basin. The thickness of the pipe determined by the amount of metal poured into the mould. Then after the completion of pouring, mould is rotated at its operational speed till it solidifies to form the requisite tubing.

12. The speed of rotation is almost double in semi centrifugal casting as compared to the true centrifugal casting.

a) True

b) False

Answer: b

Explanation: In semi-centrifugal casting method, complicated but axi-symmetric shapes of casting can be possible to make and this is accomplished by pouring of molten metal into the mould, which is rotated about a vertical axis. And the rotating speeds used in this process are not as high as in the case of true centrifugal casting.

13. Which of the following types of centrifugal casting process is used for the casting, whose shape of casting is not axi-symmetric?

a) True centrifugal casting

b) Semi centrifugal casting

c) Centrifuging

d) Full centrifugal casting

Answer: c

Explanation: Centrifuging is a process which is used in order to obtain higher metal pressures during solidification when the shapes of the casting are not axi-symmetrical. This process is mainly suitable for small jobs of any shape. In this method, a number of small jobs are joined together in a radial manner and then the further process of casting is done.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Continuous Casting”.

1. Which of the following methods of casting is the fastest method for the production of constant cross-section shapes of casting?

a) Permanent mould casting

b) Centrifugal casting

c) Continuous casting

d) Die casting

Answer: c

Explanation: Basically, the starting point of any structural steel product is the ingot which is rolled through a number of mills before a final product such as a slab or a bloom. Continuous casting allows for the fast production of constant cross-sectional shapes of the casting in large volume.

2. The rolling process is an essential part of the continuous casting for the production of castings.

a) True

b) False

Answer: b

Explanation: Wide adopting of continuous casting has changed that scenario by directly casting of slabs, billets and blooms without going through the rolling process. So in continuous casting, there is no requirement of any rolling operation, this makes the process very fast and economical too.

3. Which of the following methods of casting is best suitable for the casting of long length slabs and billets?

a) Investment casting

b) Permanent mould casting

c) Die casting

d) Continuous casting

Answer: d

Explanation: To produce continuously long length metallic objects in mass production directly from the liquid metal this technique can be used. Liquid metal is allowed through the die opening and the output of the die is a solid crust on which water will be sprayed to cool the material at a faster rate.

4. Which of the following is the approximate thickness  of the skin of casting formed at the initial of continuous casting process?

a) 1 to 5

b) 10 to 25

c) 25 to 75

d) 75 to 150

Answer: b

Explanation: In continuous casting process, the liquid steel is poured into a double-walled, bottomless water-cooled mould where a solid skin is formed quickly and a semi-finished skin emerges from the open mould bottom. The skin formed in the mould is approximately 10 to 25 mm in thickness.

5. In continuous casting, different cooling rates provide different properties to the castings.

a) True

b) False

Answer: a

Explanation: In continuous casting, depending on properties required by object, different cooling rates are provided. For example, intense cooling by water sprays makes the casting of fine structure and with good hardness, and if the air cooling is done then the casting of a coarse structure is made with good ductility in it.

6. Which of the following terms is used for the intermediate pouring vessel in continuous casting?

a) Tundish

b) Biscuit

c) Platen

d) Runner

Answer: a

Explanation: In continuous casting process, the molten steel is collected in a ladle and kept over a refractory lined intermediate pouring vessel which is termed as tundish. The steel is then poured into water cooled vertical copper moulds which are approximately 450 to 750 mm in length.

7. Before starting of casting process, a dummy starter bar is used in the continuous casting method.

a) True

b) False

Answer: a

Explanation: At initial, a dummy starter bar is kept in the mould bottom. After starting of a process, as the metal level rises to a desirable height then the starter bar is withdrawn from the system. The initial metal freezes onto the starter bar as well as the periphery of the mould, and then this solidified shell supports the liquid metal as it moves downwards.

8. Which of the following parts is used for the support of steel shell in continuous casting?

a) Steel balls

b) Conveyor belt

c) Steel rollers

d) Steel frame

Answer: c

Explanation: In continuous casting, steel shell is mechanically supported by steel rollers as it moves down through the secondary cooling zone for the complete solidification then the water is sprayed onto the shell surface to solidify the casting, after that it is cut to the desired length of the billet or slab.

9. Higher extent of automation can be possible in a continuous casting method.

a) True

b) False

Answer: a

Explanation: The operations in the continuous casting cannot be done manually, so a higher extent of automation is introduced in this technique to perform the operations easily. For example, torch cutters, water sprayers, tundish, metallic rollers etc. are the automatic devices which are used to make the process fast and easy.

10. Continuously cast products in the continuous casting show very less segregation.

a) True

b) False

Answer: a

Explanation: In continuous casting, the dense metal is accumulated in a unitary form which is properly supported by the mould. This technique makes the better quality of casting products and the continuously cast products in the continuous casting show very less segregation.

11. Which of the following is used for the reduction of friction between the mould’s surface and metal strand?

a) Water

b) Casting powder

c) Oil

d) Grease

Answer: b

Explanation: In continuous casting, at the beginning of solidification of molten metal in the mould, the casting powder is added onto the top side of molten metal in the mould. This casting powder melts and penetrates between the surfaces of the mould and solidified strand to minimize the friction, which leads to completion of the operation in less time.

12. Defects like diagonal cracks and blow holes can be induced in the casting by the oscillation of mould.

a) True

b) False

Answer: b

Explanation: Mould oscillation leads to a generation of shape defects of the casting. But the internal defects like blow holes, diagonal cracks or any kind of cracks are originated in the cast product due to the mechanical and thermal stresses which are caused by the non-uniform cooling of casting in the secondary zone.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Squeeze Casting”.

1. The main purpose of squeeze casting is to produce castings of large volume with high segregation.

a) True

b) False

Answer: b

Explanation: In squeeze casting, the objective is to make the castings of compact size with good strength. In this technique, product quality is greatly improved by solidifying the casting under heavy pressure to prevent the formation of shrinkage defects and retain dissolved gases in solution until freezing is complete.

2. In the squeeze casting method, extreme care is taken while pouring of molten metal into the die cavity.

a) True

b) False

Answer: a

Explanation: Very carefully metered charge of molten metal is poured into the die cavity as to maintain the exact amount required for the casting. Excess of molten metal can lead to an increase in work time and the overall working efficiency is also decreases. So to avoid this problem, extreme care should be taken at the time of pouring.

3. What should be the range of pressure  under which molten metal is pressed to form the castings by squeeze casting method?

a) 10 to 50

b) 50 to 140

c) 140 to 240

d) 240 to 300

Answer: b

Explanation: In squeeze casting, the punch portion of the upper die is forced into the cavity by displacing the molten metal under pressure until it fills the annular space between the die and the punch. Normally, the metal is kept under pressure of 50 to 140 MPa to avoid the formation of shrinkage defects.

4. At the starting of the casting process, the punch should be lowered down in such a way to form a tight seal.

a) True

b) False

Answer: a

Explanation: The punch and die portion are separated at the initial of the casting process and the holding furnace holds the molten metal at the requisite temperature. After the pouring of molten metal into the cavity, the punch is lowered down in such a way that it forms a tight seal to avoid inclusion of any gases to the castings.

5. Shrinkage cavities cannot be reduced by application of pressure; it can only be avoided by having a tight seal in the casting system.

a) True

b) False

Answer: b

Explanation: After pressing of punch onto the molten metal, melt loses heat rapidly because of its contact with the metallic die. Then solidification occurs, this solidification under pressure is mainly claimed to be responsible for the reduction in the shrinkage cavities in the resulting castings.

6. The method of squeeze casting is very expensive to use because of its less productivity.

a) True

b) False

Answer: b

Explanation: The squeeze casting has very low gas entrapment, lower shrinkage cavities, lower die costs, and very high quality of surface with fine details of castings. Also, it produces fine grain size to improve the mechanical properties of the castings. Aluminum and copper alloys component can be manufactured easily by this method with high productivity.

7. Which of the following methods of casting is also known as the liquid metal forging?

a) Die casting

b) Continuous casting

c) Permanent mould casting

d) Squeeze casting

Answer: d

Explanation: Squeeze casting is also known as the liquid metal forging, which combines the advantages of casting and forging processes. This process is widely used for the production of quality castings; this is mainly achieved by improving the contact between the molten metal and the die by pressurization.

8. In squeeze casting, the instant contact between the melt and the die results into the formation of ductile castings of coarse structure due to slow rate of cooling.

a) True

b) False

Answer: b

Explanation: The cooling rate of the molten metal is mainly increased during the solidification stage of the squeeze casting. The instant contact between the melt and the die surface produces a rapid heat transfer condition that makes the casting of good harden-ability with fine grain structure.

9. An intermediate feeding component takes part in the in-direct type of squeeze casting.

a) True

b) False

Answer: a

Explanation: Generally, squeeze casting has two types of ways for performing casting operation. Direct and in-direct, in direct squeeze casting, pressure is directly applied to the metal, while in in-direct squeeze casting; pressure is applied on the molten metal through an intermediate feeding part.

10. Which of the following factors is not considered for the determination of pressure level in the squeeze casting?

a) Shape of the casting

b) Fluidity of the alloy

c) Freezing range of alloy

d) Moulding material

Answer: d

Explanation: In squeeze casting, time duration is mainly determined by the casting configuration, alloy type and heat transfer conditions. After the completion of the solidification process, pressure is no longer required in the operation. Then the casting is safely taken out from the die for the further process of machining.

11. Extension of holding time of casting under the punch leads to more strength of the castings.

a) True

b) False

Answer: b

Explanation: Extended holding time never makes the castings of good strength; even it may cause wall cracking and problems with punch withdrawal due to thermal contraction of the casting. So a rule is set in the squeeze casting that the maximum holding time is about one second per mm of section thickness.

12. In squeeze casting, die preheating temperature is maintained within close limits and very precise.

a) True

b) False

Answer: a

Explanation: In squeeze casting, the die temperature has to be monitored within close limits, because too low preheating temperature of die may result in quick solidification and cold laps in the castings. And too high temperature may cause the surface defects and welding of the die with casting.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Slush Casting”.

1. Which of the following methods of casting is employed for the casting of open and hollow objects like boots, toys, dolls etc?

a) Die casting

b) Continuous casting

c) Squeeze casting

d) Slush casting

Answer: d

Explanation: Slush casting is an excellent method for producing of open and hollow objects like boots, shoes, toys and automotive products, such as protective skin coatings on arm rests, head rests and crash pads. This method is very simple and widely used for the production of ornamental objects.

2. Slush casting method always requires automation for the production of castings.

a) True

b) False

Answer: b

Explanation: For the long runs, slush casting may require a conveyor system for the production process. But generally, it can be a simple handle operation for limited production of castings. So conventionally the work and almost all the operations are performed manually to make the process economical.

3. In slush casting, the method of multiple pouring leads to the fast production of castings.

a) True

b) False

Answer: a

Explanation: In slush casting, one pour and multiple pour methods are used. One pour method in which, finished or semi-finished products can be made by one slushing step and in multiple pour method, number of slushing steps are used for the casting that results into fast production of products.

4. A permanent mould is used in the slush casting with some variations for the making of castings.

a) True

b) False

Answer: a

Explanation: Normally a slush casting is produced by pouring of molten metal into an open top permanent mould and then the mould is inverted after the forming of a solid thin layer in the mould. The mould is reheated and the hollow casting is safely taken out from the mould for further processing.

5. Slush casting method is easily applicable to the high melting temperature materials.

a) True

b) False

Answer: b

Explanation: The high melting temperature materials such as aluminium and brass cannot be cast easily by slush casting method because temperature of melt can make defects in the mould and casting itself, so low melting temperature materials such as tin, zinc and lead are mainly used in the slush casting process.

6. The thickness of the metallic wall of the mould can be used to determine the wall thickness of the casting part in slush casting.

a) True

b) False

Answer: a

Explanation: The wall thickness of the casting part not only determined by the thickness of the metallic wall of the mould, but it can also be obtained by considering the other factors like length of time the mould is preheated, and the amount and type of molten metal are used in the process of slush casting.

7. Porosity in the moulding part cannot affect the casting part in slush casting process.

a) True

b) False

Answer: b

Explanation: In slush casting, if porosity is present in the mould part, then it can cause detrimental effects on the casting part such as pin-holing, surface gloss reduction and voids in the casting. So, extreme care should be taken while selecting the die or for the preparation of the same.

8. It is not easy to control the internal geometry of the castings made by a slush casting method.

a) True

b) False

Answer: a

Explanation: In slush casting, it is not easy to control the internal geometry of the castings because when the mould is inverted some of the material remains sticks to the solidified wall of the casting, which results into the formation of irregularities at the interior part of the casting, which then requires expensive machining.

9. In slush casting, much of molten metal is wasted during the process of inverting mould.

a) True

b) False

Answer: b

Explanation: The material does not get wasted in slush casting, instead this process saves a lot of molten metal by collecting it and that is reused for the other slushing steps. This process makes the casting lighter in weight by saving the molten metal; hence this process is good in an economical way.

10. There is no requirement of any type of cores in the method of slush casting.

a) True

b) False

Answer: a

Explanation: In slush casting, there is no need of using any core because the hollow section of the casting is made by inverting the mould, which poured down the remains melt after the formation of a solidified layer at the interior part of the mould. So it eliminates the use of core with achieving the desired nature of hollow part of the castings.

11. Which of the following moulds is used in slush casting, in which mould is broken to remove the castings?

a) Copper mould

b) Iron mould

c) Bronze mould

d) Zinc mould

Answer: c

Explanation: Bronze moulds are used in some cases of the slush casting when the better surface finish of the exterior part is required. When the metal hardens, the mould is broken to remove the castings. The inside of each cast retains molten texture while the exterior part is very smooth and shiny.

12. Casting’s strength and other mechanical properties are easily controlled in the slush casting method.

a) True

b) False

Answer: b

Explanation: When manufacturing by slush casting, it is very difficult to control the strength and other mechanical properties accurately because of the formation of irregularities at the inside portion of the casting. Properties can be enhanced or improved by providing heat treatment to the metal casting.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “CO 2 Process”.

1. Which of the following moulds or moulding is also known as sodium silicate process.

a) Shell moulding

b) Permanent moulding

c) Slush moulding

d) Co 2 moulding

Answer: d

Explanation: Carbon dioxide moulding is also known as sodium silicate process is one of the widely used processes for preparing of moulds and cores. Basically, sodium silicate is used as a binder, but it binds the sand particles only in the presence of Co 2 . Co 2 is passed through the mould to tighten it, as shown in below figure. casting-questions-answers-co2-process-q1

2. Co 2 moulding is mainly used for the increase in strength and hardness of the moulds and cores.

a) True

b) False

Answer: a

Explanation: Mould is prepared by adding sodium silicate binder. Co 2 gas is supplied to the mould for sufficient time. It reacts with sodium silicate and produces silica gel which has better bonding properties. Due to this strength and hardness of the large sized moulds and cores can be increased.

3. How much percentage of sodium silicate (Na 2 SiO 3 ) is added to the sand mixture in Co 2 moulding?

a) 0 to 2 %

b) 2 to 6 %

c) 6 to 10 %

d) 10 to 14 %

Answer: b

Explanation: No other things like clay, water and resins are added to the sand except sodium silicate, which reacts with the sand mix to increase the flow-ability to fill up corners and intricate contours. Then the Co 2 is supplied to the mould and reaction takes place as follows:

Na 2 SiO 3 + Co 2 —–> SiO 2 + Na 2 Co 3

Where, SiO 2 is having gelling action .

4. Continuous passing of Co 2 through the mould can decrease the strength of mould and results in a weak mould.

a) True

b) False

Answer: b

Explanation: Continuous passing of Co 2 always results in a strong and hard mould. More the passing of Co 2 more will be the strength of the mould. Only the drawback is the decrease in permeability and collapsibility of the mould. Much passing of Co 2 gas results into difficult breathing of the mould.

5. How much time  is usually required for the passing of Co 2 through the mould?

a) One

b) Two

c) Five

d) Seven

Answer: a

Explanation: In Co 2 moulding, mould of sand is hardened by passing of Co 2 for about one minute. The Co 2 gas forms a weak acid that hydrolyzes the sodium silicate (Na 2 O, SiO 2 ) solution to form amorphous silica gel which acts as the bond and sodium silicate itself also provides some bonding action.

6. Additives can be used for the non-ferrous application to avoid the poor collapsibility of the mould.

a) True

b) False

Answer: b

Explanation: In Co 2 moulding, poor collapsibility of the mould is a major disadvantage. Although some additives are used for the improvement in the properties of ferrous metal castings, these additives which are added to the sand mixture, cannot be applicable for the non-ferrous applications.

7. Sometimes over-gassing can cause the sticking of pattern to the mould in Co 2 moulding.

a) True

b) False

Answer: a

Explanation: In Co 2 moulding, over-gassing and under-gassing can affects the properties of cured sand adversely. When the continuous passing of Co 2 is done for long time, this may results into sticking of pattern with the mould which cannot be removed easily, so proper care should be taken while passing of Co 2 gas.

8. It is very safe to use Co 2 in Co 2 moulding, so it eliminates the use of any shielding apparatus.

a) True

b) False

Answer: a

Explanation: In Co 2 moulding, the process uses relatively safe carbon dioxide gas and it does not cause any of the sand disposal problems or any kind of odour while mixing and pouring. So the using of carbon dioxide gas is very safe to human operators. And so, no any equipment is required for the shielding.

9. Which of the following additives are added to the sand in Co 2 moulding for the improvement in collapsibility of the sand?

a) Copper oxide

b) Wood flour

c) Aluminium oxide

d) Oil

Answer: c

Explanation: After the preparation of the sand mixture by adding sodium silicate to the sand, the next step is to add additive, in which mainly aluminium oxide is added and sometimes molasses are also added to impart the favorable properties and for the improvement in the collapsibility of the sand mix.

10. Co 2 moulding process is an ideal process, where speed and flexibility is the prime requirement.

a) True

b) False

Answer: a

Explanation: In Co 2 moulding, moulds and cores of varied sizes and shapes can be formed, this is mainly achieved by the using of binder sodium silicate that can binds the sand in any shape and size, and that is further tightened by the passing of Co 2 gas. This makes the moulding process very fast and flexible, so this process is more economical, where speed and flexibility is the prime requirement.

11. Moisture from the mould can be removed by using of dryer or heater in Co 2 moulding.

a) True

b) False

Answer: b

Explanation: In Co 2 moulding, water is never added while preparing a sand mixture. Instead of water, sodium silicate is added to act as a binder. Hence the moisture is completely eliminated from the mould. So, this process provides great dimensional tolerances and high accuracy in the production of castings.

12. Co 2 moulding is a kind of sand moulding, but it is not economical than the green sand moulding.

a) True

b) False

Answer: a

Explanation: Better surface finish of castings with close tolerances are produced by Co 2 moulding, but it is still not economical than the green sand moulding because this process uses expensive devices like Co 2 cylinder, hoses, regulator, hand held applicator gun or nozzle etc., and the processes in green sand moulding are simple and no expensive devices are required, due to this, green sand moulding is more economical.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Inspection and Testing”.

1. Inspection of castings is mainly carried out to detect any flaws in the castings.

a) True

b) False

Answer: a

Explanation: Inspections are mainly carried out before a lot of castings have been completed to detect any flaws that may have occurred in the process so that corrective measures can be taken to remove the defect in the remaining units. Many ways or methods are performed to inspect the castings.

2. In inspection of castings, salvaging of defective castings cannot be possible in any condition.

a) True

b) False

Answer: b

Explanation: Defective castings can be salvaged, it mainly depends upon the nature and extent of the defect in the castings. Sometimes defective casting is completely rejected and re-melted for their material content, and then this liquid metal is reused for the production of castings.

3. In inspection of castings, destructive type of testing is more reliable than the non-destructive testing.

a) True

b) False

Answer: b

Explanation: Destructive type of testing suffer from the disadvantage that the saw cuts may miss the flaw or the sample may not represent the behavior of the entire lot, and as the name shows that it damages the product while testing of the castings. So, non-destructive tests are generally more commonly relied upon than destructive tests.

4. Which of the following methods is best for examining surface flaws on the castings?

a) Pressure test

b) Magnetic particle inspection

c) Visual inspection

d) Acoustic emission test

Answer: c

Explanation: Visual inspection is a type of non -destructive testing technique that provides a means of detecting and examining the variety of surface flaws, such as surface finish, discontinuities and surface cracks on the castings. This method is very cheap and widely used because most of the surface defects and roughness can be observed easily.

5. Visual inspection is more economical than the other methods of non-destructive testing.

a) True

b) False

Answer: a

Explanation: When other non-destructive techniques are used to detect surface cracks, visual inspection often provides a useful supplement. And the time delay and costs involved in other NDT methods would be unacceptable where large tonnage of products are produced each day. So, direct visual inspection is more economical to use for inspection of castings.

6. Visual inspection can be the complete inspection for detecting any defects in the castings.

a) True

b) False

Answer: b

Explanation: Visual inspection can observe most of the surface defects and roughness of the castings, but the defects at the interior part of the surfaces, which cannot be observed easily by naked eyes. So other methods of non-destructive testing are used where small areas are subjected to sensitive tests to detect surface blemishes.

7. It is not possible to detect malformed castings and shut running defects in visual inspection.

a) True

b) False

Answer: b

Explanation: Visual inspection of each casting ensures that none of its features has been omitted or malformed by moulding errors, shut running, or mistakes in cleaning. Most of the surface defect can be observed easily at this stage, but for sensitive testing, other expensive methods of NDT are implemented.

8. Liquid penetrant testing  is mainly used for detecting internal blow holes defects in the castings.

a) True

b) False

Answer: b

Explanation: Liquid penetrant testing  is a non-destructive test method used for revealing discontinuities that are opened to the surface. The main reason for using penetrant inspection is for locating cracks, pores and other flaws which are opened to the surface being inspected.

9. Which of the following types of light is preferred for using fluorescent penetrant in liquid penetrant testing  method?

a) Normal light

b) Monochromatic light

c) Ultraviolet light

d) Red light

Answer: c

Explanation: In LPT method, the objective is accomplished by entrapment of the inspection liquid by the flaws followed by visual inspection of the surface under ultraviolet light  and for visible dye penetrant, normal light can be used for the inspection process.

10. In liquid penetrant testing  method, preparation of testing surface is very critical.

a) True

b) False

Answer: a

Explanation: For the use of penetrant inspection, proper preparation of the test surface is critical because unprepared surface will only reveal gross porosity and large cracks on the surface. So for preparing the surface for testing, process like machining, caustic etching, acid pickling etc. are used.

11. Which of the following processes is preferred for preparing aluminium ingots for liquid penetrant testing method?

a) Machining

b) Caustic etching

c) Grinding

d) Acid pickling

Answer: d

Explanation: When liquid penetrant test is used for aluminium ingots, before the test, the surfaces of the aluminum ingots are prepared or treated with the acid pickle. This process is basically known as acid pickling and it is recommended in preference to all other processes like caustic etching, machining etc.

12. Which of the following inspections is used for detecting invisible surface defects in a nonmagnetic casting?

a) Visual inspection

b) Dye penetrant inspection

c) Radiographic examination

d) Ultrasonic inspection

Answer: b

Explanation: Dye penetrant inspection method is mainly used to detect invisible surface defects in a nonmagnetic casting. The casting is cleaned by brushing, and then spraying or dipping of the casting is done into a dye containing a fluorescent material. Then for inspection, casting is dried and viewed in darkness that reveals the discontinuities in the surface.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Inspection Procedures”.

1. Which of the following methods of inspection is mostly used for ferromagnetic materials?

a) Acoustic emission test

b) Ultrasonic inspection

c) Magnetic particle inspection

d) Visual inspection

Answer: c

Explanation: Magnetic particle inspection  is a method of locating surface and subsurface discontinuities in ferromagnetic materials. In this method, the material or part is magnetized and then the magnetic discontinuities occur which indicates the size, shape and extent of discontinuities.

2. In MPI method, the magnetic discontinuities lie in a direction parallel to the direction of the magnetic field.

a) True

b) False

Answer: b

Explanation: In MPI method, after the magnetization of the material or part which to be inspected, the magnetic discontinuities that lie in a direction generally transverse to the direction of the magnetic field. This causes a leakage field to form at and above the surface of the part, which indicates the presence of surface discontinuities.

3. Any type of particles can be used for the detection of surface discontinuities of material in MPI method.

a) True

b) False

Answer: b

Explanation: In MPI method, the presence of discontinuities and the leakage field is mainly detected by the use of finely divided ferromagnetic particles applied over the surface, with some of the particles being gathered and held by the leakage field. This magnetically held collection of particles to form an outline of discontinuity, which defines the characteristics of the surface discontinuities.

4. Magnetic particle inspection is a very sensitive technique for the detection of defects in the castings.

a) True

b) False

Answer: a

Explanation: Magnetic particle inspection is a highly effective and sensitive technique for revealing cracks or similar defects at or just beneath the surface of castings made of ferromagnetic metals. This method is widely used where high accuracy and complete defects free castings are required.

5. For the detection of discontinuities beneath the surface, liquid penetrant testing method can be used.

a) True

b) False

Answer: b

Explanation: It is very important to detect discontinuities just beneath the surface because such cleaning methods as a shot or abrasive blasting tend to close a surface break that may go undetected in visual or liquid penetrant testing. So, magnetic particle inspection is preferred for the detection of discontinuities beneath the surface.

6. Which of the following methods is best for detecting interior flaws in the castings?

a) Liquid penetrant test

b) Visual inspection

c) Magnetic particle inspection

d) Ultrasonic inspection

Answer: d

Explanation: In the ultrasonic inspection, a beam of high frequency sound waves is introduced into material for the detection of interior flaws in the material. Then the sound wave travels through the material with some loss of energy and are reflected at interfaces, which are further analyzed to define the presence and location of flaws in the casting.

7. Coarse grained structures of casting material lead to increase attenuation in ultrasonic inspection.

a) True

b) False

Answer: a

Explanation: Coarse grained structures in thick plates, ingots and cast materials cause considerable increase in attenuation, that shows more loss of energy during an inspection of the castings. It mainly occurs due to scattering and diffraction at grain boundaries of the casting material. This is known as ultrasound attenuation.

8. Ultrasound attenuation has no affects on the detection of discontinuities or defects in the castings.

a) True

b) False

Answer: b

Explanation: In ultrasonic inspection, ultrasonic beam intensity decreases exponentially with the metal travel distance. Ultrasound attenuation in metal influences discontinuity detection greatly and also the material characterization technique. So, it is very important to establish attenuation measurement practices to carefully perform the inspection.

9. Which of the following formulas is used for the calculation of ultrasonic attenuation coefficient ?

a) α = 10 log(A 0 /A)/X

b) α = 20 log(A 0 /A)*X

c) α = 10 log(A 0 /A)*X

d) α = 20 log(A 0 /A)/X

Answer: d

Explanation: Ultrasonic attenuation coefficient  is calculated from the following equation-

α = 20 log(A 0 /A)/X

Where, A 0 and A are the ultrasound amplitudes before and after travelling through the material, and X is the travel distance. The measurement of attenuation coefficient is mainly used to find qualitative and quantitative information on the internal structure of products or castings.

10. In ultrasonic inspection, some standards are taken as a reference to measure the size of discontinuity in the material.

a) True

b) False

Answer: a

Explanation: In ultrasonic inspection, the instrument is adjusted using a series of reference standards in the form of cylindrical blocks containing some flat bottom holes of specified sizes at different depths. So the discontinuity size is easily determined by comparing the reflected signal amplitude with that reflected by a flat bottom hole at a similar depth.

11. Monitoring of porosity defects in casting by ultrasonic inspection is very difficult.

a) True

b) False

Answer: a

Explanation: Individual pores do not produce any distinguishable indications under testing conditions. The ultrasonic indication of centre line porosity is typically presented or revealed in the form of noise. This makes it very difficult to distinguish between porosity and large grained structure that gives similar ultrasonic indications.

12. In ultrasonic inspection, there is no chance of rejection of good material.

a) True

b) False

Answer: b

Explanation: In ultrasonic inspection, plates or ingots with large grain structure may produce a similar effect or indication as produce by the porosity defects in the castings, so this can result in rejection of good material. In such cases, ultrasonic data acquisition systems are used, which offer digital filtering to eliminate the problem.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Visual Inspection”.

1. What does M.F.F.T. stand for?

a) Maximum Flow Filling Temperature

b) Minimum Flow Filling Temperature

c) Minimum Film Forming Temperature

d) Maximum Film Forming Temperature

Answer: c

Explanation: M.F.F.T. stands for Minimum Film Forming Temperature, at this temperature, the aqueous polymer bonds with itself. This bonding takes place in a semi dry state to form a continuous film.

2. Which of the following was not a classification of a subject taking the MFFT?

a) Slow accurates

b) Slow in-accurates

c) Fast-Accurates

d) Reflectives

Answer: a

Explanation: The subjects on taking the MFFT, the subjects were then classified into four categories namely, fast-accurates, reflectives, impulsives and slow-inaccurates. Slow-accurates was not one of the classifications.

3. Which subject classification of the MFFT has the characteristics, short time spending and high errors making?

a) Fast-accurates

b) Slow-inaccurates

c) Reflectives

d) Impulsives

Answer: d

Explanation: According to the subject classification of MFFT, the category of impulsives has the characteristics of spending less time and making more errors.

4. Which subject classification of the MFFT has the characteristics, long time spending and less errors making?

a) Fast-accurates

b) Slow-inaccurates

c) Reflectives

d) Impulsives

Answer: c

Explanation: According to the subject classification of MFFT, the category of reflective has the characteristics of spending long time and making less errors.

5. Which subject classification of the MFFT has the characteristics, short time spending and few errors making?

a) Fast-accurates

b) Slow-inaccurates

c) Reflectives

d) Impulsives

Answer: a

Explanation: The category of fast-accuratives has the characteristics of spending less time and making few errors, and this is according to the subject classification of MFFT.

6. Which subject classification of the MFFT has the characteristics, long time spending and high errors making?

a) Fast-accurates

b) Slow-inaccurates

c) Reflectives

d) Impulsives

Answer: b

Explanation: According to the subject classification of MFFT, the category of impulsives has the characteristics of spending long time and making more errors.

7. Which of the following cannot be detected using visual inspection?

a) Blowholes

b) Crack within the cast

c) Tears

d) Rattails

Answer: b

Explanation: Visual inspection can be used for detection of many kinds of defects like cracks, tears, blowholes, rattails, metal penetration, swells, shifts and many more. But for detecting cracks within the cast, visual inspection is not the way.

8. Negative surface irregularities cannot be caused by which of the following factor?

a) Slag inclusion

b) Oxidation pitting

c) Nitride pitting

d) Shrinkage

Answer: c

Explanation: For the formation of negative surface irregularities, slag and oxide inclusion, oxidation pitting, gas and shrinkage are very important factors, but not nitride pitting, as it does not cause negative surface irregularity.

9. Positive surface irregularity is caused by excess metal penetration.

a) True

b) False

Answer: a

Explanation: During the formation of positive surface irregularity on the casting, an excess amount of metal has to penetrate into the ceramic mold material, or there should be an entrapment from air to liquid next to the pattern.

10. Visual inspection is essentially carried out using a magnifying glass.

a) True

b) False

Answer: b

Explanation: Visual inspection can be carried out using various equipment such as Mark 1 eyeball or Mark 0 eyeball. For carrying out visual inspection, detecting defects can be done using the naked eye too.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Dimensional Inspection”.

1. In a dimensional inspection, a part of casting can be broken for the proper inspection of casting.

a) True

b) False

Answer: a

Explanation: Dimensional inspection is generally carried out to make sure that the castings produced have the required overall dimensions including the allowances for the machining process. Sometimes it is necessary to break a part of the casting to take measurements of inside dimensions properly.

2. Which of the following machines is used for checking the dimensions more accurately?

a) Radiography machine

b) UV machine

c) Coordinate measuring machine

d) Universal testing machine

Answer: c

Explanation: Coordinate measuring machine  is basically used for the measurement of dimensions more accurately. However, the checking of dimensions of any casting or material can be done manually but the CMM makes more accurate and precise measurement with high automation.

3. Dimensional inspection does not affect machining of casting rather it may increase time and cost of machining process.

a) True

b) False

Answer: b

Explanation: Dimensional inspection mainly reduces the time and cost of machining when the casting is made. This method gives accurate details and proper forecasting can be possible before the machining process which greatly helps to make the casting more economical and reliable for the application.

4. Computerization in dimensional inspection improves the speed and accuracy of measuring casting dimensions.

a) True

b) False

Answer: a

Explanation: Computerization greatly improves the speed and accuracy of measuring casting dimensions, for example, the coordinate measuring machine  makes the process repetitive and acts as a statistical tool which makes easier for the producers to inspect the casting more comfortably.

5. Maintaining of very sharp tolerances of casting cannot be possible by dimensional inspection.

a) True

b) False

Answer: b

Explanation: To ensure a part meets dimensional requirements, dimensional inspection helps greatly, in which a metal casting facility can check the dimensional accuracy of a part manually or by the help of coordinate measuring machine . And any tolerance can be maintained easily by dimensional inspection.

6. Heat and the head pressure of molten metal can cause variation in the dimensions of a casting.

a) True

b) False

Answer: a

Explanation: Heat and the head pressure of molten metal can make a variation in the dimensions of casting, the heating and cooling of molten metal which results into expansion and contraction of it respectively, this changes the volume of a mould cavity and further results into the undesired dimensions of the casting.

7. It is not necessary to measure critical dimensions of compact or large castings for dimensional inspection.

a) True

b) False

Answer: b

Explanation: It is very important to measure critical dimensions of compact or large castings for dimensional inspection. Measurement of large volume of castings is done for more often to check possible drifts, particularly drift is mainly occurs due to the wearing of a pattern.

8. In dimensional inspection, the cost involved in measuring tools is very high.

a) True

b) False

Answer: a

Explanation: The accuracy of the measuring tools is just as important as the dimensional accuracy of the castings, that’s why the measuring tools are made of high quality and strength which makes it expensive to use. Sometimes, the gauges or fixtures needed to check the dimensions are supplied to the casting facility by the customer for better accuracy.

9. By the data concluded from dimensional inspection, it is possible to form casting of exact required dimensions.

a) True

b) False

Answer: b

Explanation: It is not possible to form a casting of exact required dimensions. The efficiency of exactness cannot be hundred percent, only it can be improved by using better and high quality equipment. Dimensions of each casting will vary slightly, so castings are specified by setting a range of values that the dimensions can fall within.

10. Narrowing the range of required dimensions make the casting more expensive and difficult to produce.

a) True

b) False

Answer: a

Explanation: The range between the lower tolerance limit and upper tolerance limit is always set by a producer to make dimensions to come within the range, but the narrowing or shortening of range makes the casting more expensive and difficult to produce, and problems also arise while testing of casting.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Testing of Mechanical Properties”.

1. Mechanical testing of material or casting involves deformation and breakage of materials.

a) True

b) False

Answer: a

Explanation: Mechanical testing often involves deformation and breakage of samples of materials. A machine called UTM  is conventionally used, in which specimen is loaded or fixed at the chuck side and it performs various types of test like tension test, compression test etc.

2. In testing materials, only un-notched specimen of standard shape and size can be used.

a) True

b) False

Answer: b

Explanation: The simplest test specimens are smooth and un-notched, but more complex geometries can be used to produce conditions resembling those in actual engineering components. Notches like holes, slots or grooves that have defined radius can be machined in specimens. This gives more accurate information about the material.

3. Apart from UTM machine, servo-hydraulic systems are also used for testing materials which can be controlled manually.

a) True

b) False

Answer: b

Explanation: Various equipment are used for mechanical testing which ranges from simple, hand-actuated devices to the complex type of equipment, for example, servo-hydraulic system is one of the complex type which is used in testing and completely controlled through computer interfaces.

4. The tension test is generally used or performed for determining static properties of materials.

a) True

b) False

Answer: a

Explanation: The tension test is the commonly used test for determining static properties of materials. The data obtained from the test is mainly used to predict failure of parts subjected to more generalized stress states. Static properties are basically related to the strength and hardness of the material.

5. Tension test of brittle material may cause unexpected failure of the material.

a) True

b) False

Answer: a

Explanation: A direct tensile load is difficult to maintain because of misalignment of specimen grips and some bending usually occurs. It has no problem while testing ductile materials because local yielding can redistribute the stress, so uniformity remains; however, in brittle materials, local yielding is not possible and cause the failure of specimen in an unexpected way.

6. In tension test, the elongation or strain in the elastic region of material can be measured with the help of extensometer.

a) True

b) False

Answer: b

Explanation: The load in the specimen can be read directly from the testing machine, while the elongation is measured with the help of extensometer. But in the elastic region, the strains are so small that cannot be measured by extensometer, so some type of magnification of the deformations are generally required to measure the strains.

7. Which of the following categories is not the part of hardness testing of materials or castings?

a) Scratch test

b) Indentation test

c) Shear test

d) Rebound test

Answer: c

Explanation: In the mechanical properties of material, hardness is basically defined as the resistance of a material to penetration. To characterize hardness, it can be divided into three primary categories such as scratch test, rebound test and indentation test. Shear test is not the part of hardness testing; it is used to measure shearing strength of the material.

8. Which of the following properties of a material is assessed by the rebound test of hardness?

a) Toughness

b) Ductility

c) Malleability

d) Resilience

Answer: d

Explanation: The rebound test of hardness has generally employed some techniques to assess the resilience of material by measuring changes in potential energy of the material. For example, testing employs a hammer that is dropped onto the surface of the material being tested; same is also used for polymers testing.

9. In indentation testing of material, the hardness is a function of force and size of the impression.

a) True

b) False

Answer: a

Explanation: Indentation test actually creates a permanent impression on the surface of material. And the hardness is a function of force and size of the impression, so the force and size of the impression can be related to the hardness which can be objectively related to the resistance of material to the permanent penetration.

10. Which of the following types of indenter is employed in Brinell hardness test?

a) Diamond pyramid

b) Diamond ball

c) Titanium ball

d) Steel ball

Answer: d

Explanation: In this test, a large steel ball of generally 10 mm diameter is used with a force of relatively large magnitude. This force is usually compatible with either 3000 kg for relatively hard materials such as cast iron and steel or 500 kg for soft materials such as aluminium and copper alloys. For very hard materials, a tungsten carbide ball is preferred.

11. In testing of mechanical properties of material, torsion test is more preferred than the tension test.

a) True

b) False

Answer: a

Explanation: The torsion test is more preferred than the tension test because shear stress and shear strain are found directly in the torsion test, rather than tensile stress and tensile strain as in the tension test. And all the deformations of ductile materials are by shear, so the torsion test is more fundamental.

12. Which of the following devices is used for the measurement of angular deformation in torsion test?

a) Tachometer

b) Extensometer

c) Troptometer

d) Slip gauges

Answer: c

Explanation: A device known as troptometer is basically used to measure angular deformation in torsion test. This device mainly consists of two collars which are clamped to the specimen at the desired gauge length, in which one collar is equipped with a pointer and the other with a graduated scale.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Destructive Testing”.

1. Destructive tests are generally much easier to interpret than the non-destructive tests.

a) True

b) False

Answer: a

Explanation: Destructive tests are mainly carried out to the specimen’s failure, in order to evaluate a specimen’s performance or material’s behavior under different loads. These tests are much easier to carry out, give more information, and are easier to interpret than non-destructive tests.

2. Destructive testing is not economical for mass production as this method destroys material for the inspection.

a) True

b) False

Answer: b

Explanation: Destructive testing is the most suitable and economic method for objects which will be mass-produced, it only involves the cost of destroying a small number of specimens which is quite negligible. Destructive test is not economical where only one or two things are to be produced.

3. In destructive testing, all the operations are performed manually, thus it does not require any technologies or electronic devices.

a) True

b) False

Answer: b

Explanation: In destructive testing, analyzing of destructive failure mode is often completed using a high-speed camera, which records continuously until the failure is detected. Detection of the failure can be accomplished by using a sound detector which produces a signal to start the high-speed camera.

4. High speed camera used in destructive testing can give very precise information about the failure of casting or material.

a) True

b) False

Answer: a

Explanation: The high-speed cameras used in destructive testing have advance recording modes to capture almost any kind of destructive failure. After the failure of casting, camera stops recording and the captured images can be played back in slow motion which shows precise information, image by image during and after the destructive test.

5. Destructive testing method can also be economical for large casting or structure.

a) True

b) False

Answer: b

Explanation: Destructive testing method can be applicable to the large structures but it is not economical because destruction of large casting or structure will cause steep downing of productivity. So for large structures or castings, other methods are used for the inspection like modeling by finite element software.

6. Which of the following tests is not the type of destructive testing of materials?

a) Stress test

b) Crash test

c) Hardness test

d) Pressure test

Answer: d

Explanation: Pressure test is basically a type of non-destructive test in which a gas is injected in a closed casting, and then the casting is dipped into water and if it produces any leak of gas in the water, that basically shows presence of defects in the casting that can be simply observed by visual inspection. And the test like a stress test, hardness test and crash test, these are related to the destructive testing of materials.

7. Which of the following tests uses a heavy pendulum for the breaking of a specimen while inspection?

a) Pressure test

b) Static tear test

c) Stress test

d) Charpy v-notch test

Answer: d

Explanation: In the Charpy v-notch test, the specimen is first heated to a specified temperature. Then it is placed in a machine and broken within five seconds. This testing machine uses a heavy pendulum to break the specimen. This test indirectly provides fracture toughness of the material or casting.

8. Charpy v-notch test can only estimate the energy absorbed by the fracturing of material.

a) True

b) False

Answer: b

Explanation: In charpy test, not only the absorbed energy, but the percentage of shear fracture area can also be measured. This is generally evaluated by observing the fracture surface of the specimen or work-piece and this estimates the relative amount of shear fracture, which looks rough or torn.

9. The dynamic tear test is mainly used for evaluating fracture properties of ultrahigh strength steel castings.

a) True

b) False

Answer: a

Explanation: The dynamic tear test is used to characterize the fracture properties of ultrahigh-strength steels and also for the aluminum and titanium alloys which generally do not exhibit any sharp transition temperature behavior. This test is performed by impact loading and results into absorption of energy at various testing temperatures.

10. In impact testing of materials, the notches are made to reduce the stress concentration.

a) True

b) False

Answer: b

Explanation: In impact testing of materials, the notches in specimen are made intentionally to increase the stress concentration so as to increase the tendency to fracture as most of the mechanical components have stress raisers. The notch material should be tough enough to withstand the impact force.

11. The fatigue performance of metallic casting is generally determined by endurance limit of the material.

a) True

b) False

Answer: a

Explanation: The fatigue performance of the material is generally evaluated by endurance limit of the metal which indicates maximum stress, stress range or stress amplitude. It is also determined by a number of load cycles which are applied to the material or casting for the evaluation of properties.

12. Which of the following parameters is also known as stress intensity factor ?

a) Creep

b) Proof resilience

c) Fracture toughness

d) Endurance

Answer: c

Explanation: The fracture toughness parameter is also called as stress intensity factor  which is used for heavy sections of high strength and low ductility material of casting developing plain strain conditions, and other energy based methods are generally used for comparatively thinner sections made of low strength and high ductility material.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Non destructive Testing”.

1. In non-destructive testing, sound test used is a very fine and accurate method of detecting flaws in the castings.

a) True

b) False

Answer: b

Explanation: Sound test is a very rough test to indicate any flaws or discontinuities in the casting. The casting is suspended by suitable support and tapping is done at the surface of the casting with a hammer that makes a variation in the tone which indicates the existence of flaws. This method does not indicate the exact location and extent of the discontinuity in the casting.

2. Impact test for detection of defects in the casting is the most crude and unreliable method of non-destructive testing.

a) True

b) False

Answer: a

Explanation: In the impact test, the casting is subjected to a blow by the help of a hammer of known weight, which basically strikes or falls on the surface of the casting. Defective castings fail due to the impact of the blow, but this method is very crude and unreliable to the material or casting which is inspected.

3. Which of the following methods of NDT requires leak proofing of casting before inspection?

a) Impact test

b) Visual inspection

c) Sound test

d) Pressure test

Answer: d

Explanation: Pressure test used on castings required to be leak proof. In this method, all the openings of the casting are closed and then gas with high pressure is introduced in it. If the casting is having a porosity or another defect, then it can be detected by leaking of gas in the water when the casting is submerged into the water.

4. Which of the following types of rays is used in radiography for the inspection of castings?

a) X- rays

b) Infrared rays

c) Ultraviolet rays

d) Visible rays

Answer: a

Explanation: Radiography uses X-rays, these rays penetrate through the castings and makes a shadow picture on a film which is placed behind the material. These rays have a very short wave length of the order of 0.001 Angstrom. And sometimes gamma rays are also used for the inspection of castings.

5. In radiography, the penetration of rays is much easier with the less density of metal or casting.

a) True

b) False

Answer: a

Explanation: The ability of rays to penetrate through the metal mainly depends on the density of metal and they can penetrate more easily where less density of metal is present and it leads to the formation of shadow picture on the film. And any defects in the casting can easily be identified from the shadow picture.

6. In penetrant testing of NDT, a liquid is penetrated into the cracks of metal by the application of pressure.

a) True

b) False

Answer: b

Explanation: Penetrant testing method is generally used for detecting very small surface cracks and it has an advantage over the magnetic particle method that it can be used for any material. A penetrant liquid is used which is drawn into the cracks or voids by means of capillary action. In this method, there is no requirement of pressure.

7. Which of the following methods of inspection uses high frequency of sound waves for the detection of flaws in the castings?

a) Penetrant test

b) Radiography

c) Pressure test

d) Ultrasonic inspection

Answer: d

Explanation: Ultrasonic inspection is used to detect defects like cracks and porosity within the interior of the casting or material. This method uses reflection and transmission of high frequency sound waves, which are much higher than the audible range and then these waves are made pass through the casting for inspection.

8. In ultrasonic inspection, a signal processing technique is used for the accurate indication of porosity in the castings.

a) True

b) False

Answer: a

Explanation: A signal processing technique is used for accurately verifying the presence of porosity and also to determine the size and volume fraction. This is mainly done by measuring the changes in frequency by using a broad band transducer, in which the front and the back surface signals of the casting are acquired and digitized.

9. Which of the following terms changes in the eddy current testing method for the detection of defects in the castings?

a) Resistance

b) Impedance

c) Conductivity

d) Capacitance

Answer: b

Explanation: In the method of eddy current testing, the impedance of a coil is changes and the coil is brought close to a conductive material which indicates the eddy current induced by the coil and thereby indicates various properties and also the defects of the casting. This method can be used effectively with both ferromagnetic and non-ferromagnetic materials.

10. There are no restrictions in the eddy current testing method; it can detect defects up to high depth in the castings.

a) True

b) False

Answer: b

Explanation: Eddy current inspection is generally restricted to the depth less than 6mm, that’s why it is not as sensitive to small open defects of high depth as liquid penetrant testing  or magnetic particle inspection . But it can replace LPT method for detection of surface connected discontinuities.

11. Eddy current testing method can also be used for the evaluation of heat damage to the metal alloys.

a) True

b) False

Answer: a

Explanation: Eddy current conductivity testing method is commonly used to assess heat damage of various heat treatable alloys. In order to have a quantitative assessment of heat damaged material, the establishment of conductivity, hardness and strength, a  relationship is required for each alloy.

12. Acoustic emission testing method is basically employed for the detection of surface discontinuities on the castings.

a) True

b) False

Answer: b

Explanation: Acoustic emission testing method, in which solid materials emit sound or acoustic emission when they are stressed mechanically or thermally to the point where deformation or fracturing occurs. This creates elastic waves which can be analyzed by an acoustic emission test system to monitor the condition of the material or casting under stress.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Mechanism of Solidification”.

1. Which of the following characteristics is mainly considered for the solidification of castings?

a) Appearance

b) Crystal structure

c) Moulding capacity

d) Surface finish

Answer: b

Explanation: A clear understanding of the mechanism of solidification and cooling of molten metal and alloys is very essential for the production of successful castings. During solidification, crystal structure of the casting material is mainly considered along with its composition at different parts of the casting.

2. A proper care should be taken while cooling or solidification of castings to avoid defect formation.

a) True

b) False

Answer: a

Explanation: A proper care is must for the solidification of castings. Unless a proper care is taken, defects like shrinkage cavity, hot tear, misrun and cold shuts are occurred in the castings. To avoid defects, a proper technique should be implemented with clear understanding of material used for the formation of castings.

3. In the case of pure metals, liquid metal should be cooled above their freezing points.

a) True

b) False

Answer: b

Explanation: Liquid metal always needs to be cooled below their freezing points before the solidification starts. This is because the energy is required to create surfaces for new crystals and the degree of super-cooling necessary is also reduced by the presence of particles which serve as the initial nuclei for crystal growth.

4. Which of the following types of crystal are formed near the mould face during solidification?

a) Big crystals with random orientation

b) Small crystals with systematic orientation

c) Small crystals with random orientation

d) Big crystals with systematic orientation

Answer: c

Explanation: When a liquid metal is poured into a mould, the mould face itself acts as the nucleus for crystal growth, and when the conductivity of the mould is high, that causes the formations of randomly oriented small crystals which grow near the mould surface. Subsequently, a temperature gradient results within the casting.

5. As the solidification progresses gradually inwards, small crystals with systematic orientation are formed.

a) True

b) False

Answer: b

Explanation: After the starting of solidification of casting material, temperature gradient is set up and by progressing inwards, long columnar crystals are formed with their axes perpendicular to the mould face. This orientation of crystal growth is basically desirable from the point of strength of the castings.

6. An alloy, unlike a pure metal, does not have a sharply defined freezing temperature.

a) True

b) False

Answer: a

Explanation: An alloy, unlike a pure metal, does not have a sharply defined freezing temperature. Due to this, the solidification of an alloy takes place over a range of temperature. This makes the separate out of the solids parts at different temperatures which possess varying compositions in the material.

7. Which of the following factors is independent to the direction of crystal growth in an alloy?

a) Thermal gradient

b) Composition gradient

c) Variation of solidus temperature

d) Material aesthetics

Answer: d

Explanation: The direction of crystal growth in an alloy depends on many factors, such as the thermal gradient within the mould, the variation of solidus temperature with composition and the composition gradient within the casting. And material aesthetics basically deals with the appearance of the casting, which is independent to the direction of crystal growth in an alloy.

8. The difference in the progress of crystallization at different points in the casting material causes fast and abrupt growth of crystals.

a) True

b) False

Answer: b

Explanation: The difference in the progress of crystallization at the different points in the casting material does not make fast growth of crystals, even this makes the hampering of crystal growth which basically restricts or retards the columnar growth of crystals starting from the moulding surface during casting process.

9. A dendritic crystal growth structure is formed by the difference in progress of crystallization at different points in the casting material.

a) True

b) False

Answer: a

Explanation: A dendritic crystal growth structure is produced when there is difference in the progress of crystallization that shows completion of crystallization at any point before with respect to another point. This is mainly caused by very small thermal gradient with a very high concentration difference. Dendritic structure formed is looks like as shown in below figure. casting-questions-answers-mechanism-solidification-q9

10. The presence of solid crystals at solid-liquid interface makes feeding of molten metal more easily.

a) True

b) False

Answer: b

Explanation: The presence of solid crystals ahead of the solid-liquid interface does not make easy feeding, even this makes more difficult to feed the liquid metal. This basically implies a greater risk of having voids within the casting which is normally referred to as centre-line shrinkage defect.

11. Which of the following parts can be used to have uniform crystallization at all over the points in the casting material?

a) Chaplets

b) Biscuit

c) Chills

d) Core

Answer: c

Explanation: To avoid the problem of difference in progress of crystallization, a large thermal gradient within the mould can be produced by having chills in the casting system. Chills generally are cooled metal block with the high thermal conductivity; this is normally placed at the mould’s end.

12. Rapid heat extraction from the casting causes narrowing of liquid-solid zone which sweeps itself across the molten metal.

a) True

b) False

Answer: a

Explanation: In solidification of casting material, it is commonly starts from the centre-line of the mould before the solidification is complete even at the mould face. In the chilled mould, due to the rapid heat extraction from the casting, a narrow like liquid-solid zone sweeps across the molten metal.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Rate of Solidification”.

1. Which of the following is mostly analyzes during the casting and solidification of casting material?

a) Mould coating

b) Mould material

c) Mould aesthetics

d) Heat transfer

Answer: d

Explanation: The quality of final casting mainly dependent on the rate of solidification as rapid solidification makes fine grains structures with better mechanical properties. The analysis of heat transfer during the casting and solidification of casting is mainly carried out to have better properties of casting material.

2. The solidification time can be increased by increasing the thickness of the mould.

a) True

b) False

Answer: a

Explanation: The temperature variation with time of the casting is generally recorded by which cooling curves are obtained for the determination of solidification time of the cast. This shows that the moulding thickness increases the solidification time of the casting material during solidification.

3. A large shape of a riser is mainly used for the casting of grey cast iron.

a) True

b) False

Answer: b

Explanation: Grey cast iron is an interesting exception where solidification occurs in two stages. The shrinkage associated with the first stage can be compensated by the expansion of the casting due to the presence of graphite flakes in the material. Due to this, there is no use of riser in the casting system.

4. Feeding of an alloy in the mould is considered to be difficult if centre-line feeding resistance  is_____

a) greater than 70%

b) less than 70%

c) less than 20%

d) 0%

Answer: a

Explanation: The difficulty of feeding an alloy in a mould is expressed by a quantity which is commonly known as centre-line feeding resistance . It is basically defined as the ratio of a time interval between start and end of freezing at centre line to the total solidification time of casting. Normally, feeding is considered to be difficult if CFR is greater than 70%.

5. Which of the following is independent of the solidification time of the casting?

a) Mould material

b) Chaplets

c) Heat transfer coefficient

d) Mould wall temperature

Answer: b

Explanation: The solidification time of the casting is generally dependent on the various parameters like mould wall temperature, heat transfer coefficient at the metal and mould interface, mould wall thickness and material of the mould. Chaplets are another part used for supporting the core in the mould.

6. Casting which is cooled quickly generally have coarse grain structure.

a) True

b) False

Answer: b

Explanation: The mould is a cavity where liquid metal is poured to solidify and form the desired shape of the casting. The rate at which castings solidify affects its microstructure, quality, and mechanical properties. Basically, the casting which cools quickly will have a fine grain structure and which cools very slowly will have a coarse grain structure.

7. Refractory coating to the metallic mould helps in reducing the chilling effect on the casting.

a) True

b) False

Answer: a

Explanation: Metallic mould is made of metal capable of withstand high temperature and coated with refractory wash to reduce its chilling effect on the cast and also facilitates the removal of cast product from the mould cavity. It also helps in better surface finishing of the casting material.

8. The scale of segregation cannot be reduced or avoided by implementing any kind of method.

a) True

b) False

Answer: b

Explanation: There is very little segregation ahead of dendrite tip because the main partitioning is of solute trapped between the dendrite side arms. The scale of this segregation can be decreased by increasing the solidification rate because the dendrite arm spacing then decreases. Segregation can also be decreased by inducing a greater number density of nuclei.

9. The transfer of heat across a gap  is given by_____

a) q = h+∆T

b) q = h/∆T

c) q = h*∆T

d) q = h-∆T

Answer: c

Explanation: The transfer of heat across a gap  is given by q = h*∆T, where q is the heat flux, h is the heat transfer coefficient of the interface and ∆T is the temperature difference between the source and the sink. Values of the heat transfer coefficient may vary from 10 to 102 for large air gap; 103 to 104 for normal castings.

10. What should be the value of biot number  for chill mould castings?

a) Less than 1

b) Greater than 1

c) Greater than 5

d) Greater than 11

Answer: a

Explanation: Chill mould castings use a massive metal mould with a large thermal capacity or water cooled metal mould, so that biot number  is always less than 1. When the melt is poured in at a temperature above its melting temperature , it first cools and then begins solidification when T = Tm.

11. The deduction of cooling rate from a simple heat balance can only be possible when the process is isothermal and the specific heats of the liquid and the solid are same.

a) True

b) False

Answer: a

Explanation: In the solidification process, extraction of heat can be achieved by applying a suitable cooling to the molten metal in order to create a heat flux. The cooling rate can be deduced from a simple heat balance only if the process is isothermal  and the specific heats of the liquid and the solid are the same.

12. Increase in mould thickness always decreases the rate of solidification of casting material.

a) True

b) False

Answer: b

Explanation: The increase in mould thickness can increase the rate of solidification of casting material. This is because the increase in thickness increases the amount of heat absorbed by mould or due to the chilling effect of the mould which is also dependent on the heat content of the molten metal.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Solidification of a Large Casting in an Insulating Mould”.

1. During the solidification of casting in an insulating mould, the heat transfer takes place from the upside of the moulding system which might cause defects in the castings.

a) True

b) False

Answer: b

Explanation: During the solidification of casting in an insulating mould, the entire casting’s thermal resistance is offered by the mould material. Hence, the analysis of freezing time is done by mainly considering the thermal resistance of the moulding material. This method usually takes more time for solidification as compared to the other methods.

2. Concave, convex and plane types of metal mould interfaces are mainly considered for the estimation of freezing time of metal.

a) True

b) False

Answer: a

Explanation: During the solidification of casting material in the mould, concave, convex and plane types of metal mould interfaces are mainly considered for the estimation of freezing time of molten metal. These types of interface show the different direction of heat transfer from the casting material to the mould.

3. In solidification of large casting in an insulating mould, precise calculations are made for the analysis of freezing time of the complex contours of casting.

a) True

b) False

Answer: b

Explanation: In solidification, to find out the freezing time of complex contours of casting, only observations are made without any use of calculations. This is mainly done to observe the basic features to know whether the analysis made underestimates or overestimates the actual freezing time of the casting material.

4. Which of the following metal-mould interfaces show the divergent nature of heat flow from the casting material?

a) Concave

b) Square plane

c) Rectangular plane

d) Convex

Answer: d

Explanation: During the solidification of casting in an insulating mould, the divergent nature of heat flow is shown by the convex type of metal-mould interface and the convergent nature is shown by the concave type interface. And plane interface reveals the straight and parallel nature of heat flow. The nature of heat flow in all three interfaces is shown in below figure.

casting-questions-answers-solidification-predominant-interface-resistance-q4

5. More divergence of heat flow from the interface shows consequently high solidification rate of the casting.

a) True

b) False

Answer: a

Explanation: Divergence of heat flow from the interface is directly proportional to the solidification rate of the casting material. More the divergence then much faster will be the solidification rate. When the heat flow is of convergent nature then consequently it will have less solidification rate of the casting.

6. The amount of heat removed from the castings is dependent on the amount of superheating in the casting.

a) True

b) False

Answer: a

Explanation: The amount of heat that should be removed from casting to make it solidify is directly proportional to the amount of superheating and also to the amount of metal present in the casting or the casting volume. Conversely, the ability to remove heat from casting is directly proportional to the amount of exposed surface area of the casting.

7. Which of the following formulas is given by Chvorinov’s rule for the estimation of total solidification time ?

a) t s = B/ n

b) t s = B* n

c) t s = B* n

d) t s = B/ n

Answer: c

Explanation: According to Chvorinov’s rule, the total solidification time (t s ) is the time from pouring to the completion of solidification which can be computed by: t s = B* n , where n = 1.5 to 2.0; V is the volume of the casting; B is the mould constant; and A is the surface area, which depends on the characteristics of the metal being casted.

8. Chvorinov’s rule is commonly used for prediction of surface finish of the casting made in the mould.

a) True

b) False

Answer: b

Explanation: Chvorinov’s rule is not used for the aspect of finishing of the casting. It is mainly used to ensure that the casting made in the mould will solidify before the riser. This is very necessary if the liquid metal within the riser is to effectively feed the casting to compensate for solidification shrinkage.

9. It is very necessary to use high refractoriness of mould material for the making of insulated mould.

a) True

b) False

Answer: a

Explanation: The mould material used should be of high refractoriness because the mould used for the solidification of casting is to be insulated. So the mould should be capable of maintaining all the thermal resistance to withstand very high temperature for the long duration of time until the casting is made.

10. The solidification of casting in an insulating mould produces casting of hard and brittle nature.

a) True

b) False

Answer: b

Explanation: During the solidification of casting in an insulating mould, the casting made is generally of ductile nature as the heat transfer to the surrounding is restricted and the casting is kept for long time in the mould which have slow solidification rate that causes coarse grain structure in the casting produced.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Solidification with Predominant Interface Resistance”.

1. Which of the following is used for the controlling of heat flow in the casting process?

a) Mechanical resistance

b) Biscuit

c) Chaplets

d) Thermal resistance

Answer: d

Explanation: In the casting process, the heat flow is generally controlled by the thermal resistance of the metal-mould interface. These interfaces can be of convex, concave or plane shape, depending on the heat flow rate required for the casting. These processes mainly include permanent mould casting and die casting.

2. Perfect wetting only occurs when there is no contact resistance phenomenon in the casting interface.

a) True

b) False

Answer: a

Explanation: The condition of no contact resistance exists only when the metal-mould contact is so close and tight that causes the occurrence of perfect wetting that is the casting gets soldered to the moulding surface. This causes the sticking problem and it becomes very difficult to extract casting from the mould cavity.

3. Superheating is the only main consideration for the existence of no contact resistance between the metal and mould.

a) True

b) False

Answer: b

Explanation: For no contact resistance between the metal and mould, the solidification process is considered by assuming that the thermal resistance at the interface is of over-riding importance. In this kind of cases, superheating is not considered for the temperature distribution in the casting solidification.

4. Good thermal conductivity of the solidified metal can lower down the surface temperature below than the freezing temperature.

a) True

b) False

Answer: a

Explanation: Good thermal conductivity of the solidified metal can provide considerable thermal resistance. Because of this, the surface temperature of the casting material can be lower down below than the freezing temperature of the casting, which results in the formation of sub-cooled solidified casting.

5. Surface irregularities of the solidifying casting can increase the temperature at the interface.

a) True

b) False

Answer: b

Explanation: The surface irregularities of the solidifying casting results in irregular contacts to establish between the die wall and the casting produced. This always results in a temperature drop across the interface. The extent of temperature drop or the degree of resistance mainly depends on the contact area, physical and thermal properties of the materials in contact.

6. The heat transfer through the interface of metal and mould is always considered as of convection mode.

a) True

b) False

Answer: b

Explanation: When the air gap forms at the interface, the heat transfer across the interface drops rapidly. The mode of heat transfer through the gap is considered to be due to both conduction and radiation, conduction is more dominant mode at the lower temperatures while radiation depends upon the surface temperatures and emissivities.

7. Conduction mode of heat transfer mainly depends upon the conductivity of the medium and the size of a gap at the interface.

a) True

b) False

Answer: a

Explanation: Conduction heat transfer depends on the conductivity of the medium and the gap size as well. Thus, the correct modeling of the heat transfer across the interface depends upon many factors like interface temperatures, surface characteristics, thermo-physical properties of the gap medium including coating material etc.

8. A gap of finite thickness at the interface of mould and metal always increases the heat flux.

a) True

b) False

Answer: b

Explanation: A gap of finite thickness separating the mould and casting interface always results in lowering of heat flux. It is the most important phenomena for controlling the solidification of the casting in the metallic mould. The time of its formation and distribution affects the temperature distribution in the casting.

9. For the complex geometries of the casting, the calculation is more difficult to obtain the air gap at the interface.

a) True

b) False

Answer: a

Explanation: In the process of casting different materials, due to complexities of material behavior, internal liquid metal pressure and the mould geometry make the calculation more difficult to obtain the air gap at the interface. To solve this, proper care is to take during the process of casting products.

10. The magnitude of the air gap at the interface of casting and mould continuously decreases with time.

a) True

b) False

Answer: b

Explanation: The constant air gap width at the interface cannot be assumed for simulation. The magnitude of the air gap continuously increases with time. The time of start of the air gap at the corner of the casting is always less than that for the middle, and the air gap never starts simultaneously at all points in the casting.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Solidification with Constant Surface Temperature”.

1. A thin water cooled mould always tends to make a casting of soft and ductile nature.

a) True

b) False

Answer: b

Explanation: Thin wall of the mould and the water cooling makes the solidification rate fast, which produces fine grain structure of the casting. The fine grain structure of casting is always brittle and hard in nature because the process is somewhat similar to quenching which also produces a casting of brittle nature.

2. Rapid cooling of strand surfaces of casting is mainly done to increase casting speed and productivity.

a) True

b) False

Answer: a

Explanation: For the casting line productivity and to increase casting speed, rapid cooling of strand surfaces must be employed. It results in the development of thermal stresses and formation of surface cracks if the casting speed and cooling conditions or the arc of casting system are not appropriate for the casting process.

3. In the continuous casting line, the solidification or cooling rate is normally very high.

a) True

b) False

Answer: a

Explanation: Solidification of metal in the continuous casting line proceeds under non-equilibrium conditions and is specified by the large cooling rate. These can lead to the occurrence of defects at cast strands such as surface or internal cracks, which might also affect the composition of the casting material.

4. The analysis of heat flow is much easy in chilled casting process compared to the other type of castings.

a) True

b) False

Answer: b

Explanation: Chilled castings present heat flow analysis much more complex than the normal type of castings. The first step in analyzing is to isolate the metal from the mould, and to consider heat flow in the molten metal separately, using the simplest possible boundary condition such as constant casting surface temperature.

5. The surface temperature of chilled casting is normally lower than the melting point of the metal.

a) True

b) False

Answer: a

Explanation: It is an essential feature of chilled castings that the surface temperature is appreciably lower than the melting point of the molten metal, which totally differs from the sand castings and it moderates to steep the temperature gradient exists in the solid metal or casting produced.

6. In any condition, the effects of superheat cannot be considered in the process of chilled castings.

a) True

b) False

Answer: b

Explanation: In chilled castings, initially a mass of liquid metal at the melting temperature suddenly cools down to the surface temperature at zero time. The effect of superheat is not considered in chilled casting, but it would be quite possible to consider superheat in the one-dimensional case, but the results obtained may be unrealistic.

7. During solidification of casting material, the successive droplets of the material take a longer time to solidify than the first droplet.

a) True

b) False

Answer: a

Explanation: During solidification of casting, the successive droplet’s interface has lower temperature gradient when compared to the temperature gradient experienced by the first droplet of the material. Thus, heat transfer occurs at low rates and successive droplets take longer time to solidify that the first droplet of the casting material.

8. Which of the following temperature ranges  can start the re-melting of droplets of casting material?

a) 400 – 450

b) 450 – 500

c) 500 – 600

d) 600 – 700

Answer: d

Explanation: As the first droplet solidified when the successive droplets make an impact to it and the temperature of the pre-solidified droplet is very close to its melting temperature. The droplet temperature is approximately greater or equals to 623 K, at which the pre-solidified droplet re-melts and shows re-melting behaviour at different time instants.

9. Thermal contact resistance can be affected by impact or thermal parameters during the casting process.

a) True

b) False

Answer: b

Explanation: The effect of thermal contact resistance on the phase change process is very important to consider during solidification. Thermal contact resistance is varied by changing the heat transfer coefficient at the interface. Thermal contact resistance is always constant throughout the process and cannot be affected by impact or thermal parameters.

10. During solidification, the interface temperature is independent to the magnitude of contact resistance.

a) True

b) False

Answer: a

Explanation: During solidification of casting material, the interface temperature which generally prevails in the absence of contact resistance has physical meaning when the contact resistance is in effect. The interface temperature is independent to the magnitude of contact resistance and is dependent only on the thermal properties.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Solidification with Predominant Resistance in Mould”.

1. In continuous casting technology, solidification of casting starts in a thick sand mould of a closed structure.

a) True

b) False

Answer: b

Explanation: In continuous casting technology, metallic mould is generally preferred. The solidification is initiated in a water-cooled open-ended copper mould. And the casting which gets shaped in the mould includes a core of liquid metal which slowly solidifies as the strand moves through the caster during the solidification.

2. Handling of very high heat flux can be possible in continuous casting technology.

a) True

b) False

Answer: a

Explanation: The solidification process starts in the mould with the secondary cooling zone using a combination of water spray and radiation cooling, which maintains high heat flux. Solidification speciality of this technology arises from the dynamic nature of the casting process which relates to handling of very high heat flux in the mould.

3. Predominant resistance in mould of casting system generally produces castings of brittle nature.

a) True

b) False

Answer: b

Explanation: Due to predominant resistance in the mould of casting system, the heat transfer does not occur easily. However, it can be done forcefully, but in normal way the casting produced is of ductile nature as the heat is kept within the casting for a longer time. But, inaccurate way of solidification might cause defects in the casting.

4. In the continuous casting process, there is a strong possibility of breaking of casting parts at the initial stage of solidification.

a) True

b) False

Answer: b

Explanation: Continuous casting process nurtures the initial thin and fragile solid shells for the avoidance of breakout during the solidification of casting. And it also eliminates the surface and internal defects from the cast product by having the proper solidification dynamics in the casting process.

5. Minimization of friction between the mould and casting surface can reduce the chances of tearing of thin parts of the casting.

a) True

b) False

Answer: a

Explanation: During solidification, prevention of sticking and tearing of the initial thin shell of the casting is a major consideration. To minimize the shell sticking and tearing, friction between the casting surface and mould wall must be kept below a critical level which depends upon the shell strength of the casting.

6. To reduce the friction between the mould’s surface and casting, a refractory coating is done to the surface of mould.

a) True

b) False

Answer: b

Explanation: Minimization of friction between the mould and casting surface and for the continuous release of the shell from the mould is achieved through the introduction of mould oscillation aided by the lubrication. Refractory coating of the mould’s surface is basically done for the finishing aspect.

7. Lubrication at the interface is arises due to the infiltration of mould slag into the gap between the mould and casting.

a) True

b) False

Answer: a

Explanation: Lubrication at the interface of mould arises from the infiltration of mould slag into the air gap. The motion of the mould relative to the solidified casting gives rise to a frictional force due to the viscosity of slag film. The frictional force generated through this mechanism is termed as liquid friction.

8. Which of the following formulas is used for the determination of solid friction  between the mould and casting during solidification?

a) f s = η s -H

b) f s = η s /H

c) f s = η s +H

d) f s = η s *H

Answer: d

Explanation: When the relative movement occurs between the casting and the solidified mould slag, then the friction force is generated by the solid-solid contact. The resulting solid friction (f s ) is expressed as f s = η s *H, where η s is the coefficient of solid friction, and H is the Ferro-static pressure of molten metal.

9. Due to mould oscillation to minimize friction, oscillation marks formed on the surface of casting does not affect the castings.

a) True

b) False

Answer: b

Explanation: The oscillation marks itself is a surface defect and its severity may prevent hot rolling. And increased thermal resistance at the bottom of mark reduces the local cooling rate which retards shell growth and coarsens the local microstructure, this can disturb the whole casting by inducing defects in the casting.

10. Analysis of frictional concept at the interface is very important and necessary for the increase in casting speed.

a) True

b) False

Answer: a

Explanation: The friction concept is very useful in explaining the increased tendency of breakout with the increase in casting speed. Analysis of friction at the interface of mould and casting is done to specify the speed of the casting process or it can also be adjusted by maintaining the amount of lubrication at the gap.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Riser Placement”.

1. The presence of chills in the mould does not have any affects on the riser mechanism.

a) True

b) False

Answer: b

Explanation: The presence of chills in the moulding system greatly affects the riser mechanism. Chills in the mould increase the feeding distance of the riser, which is basically achieved by providing a sharp thermal gradient with the consequent decrease in the feeding resistance of the riser mechanism.

2. For a single riser in the casting system, the chill should be placed at the ends of the riser.

a) True

b) False

Answer: a

Explanation: To have proper directional solidification and to maintain the riser mechanism, the chill used should be placed at the ends of the riser. When more than one riser is used in the casting system then the chill should be placed at the midway between the two risers to have accurate and systematic solidification.

3. Which of the following equations defines the form of risering curve in the riser mechanism?

a) x = a* + c

b) x = a/ + c

c) x = a/ + c

d) x = a* + c

Answer: c

Explanation: The equation for a risering curve in the riser system is given by: x = a/ + c, where a is the freezing constant for the molten metal, b is the contraction ratio from liquid phase to the solid phase and c is a constant depending on the different media around the riser and the casting.

4. For a casting with a high area to volume  ratio, one central riser can be enough to feed the entire casting.

a) True

b) False

Answer: b

Explanation: Normally, for casting with a high area to volume  ratio , usually more than one riser is required. And for the low area to volume  ratio casting like cube and sphere, one central riser can be used to feed the entire casting. In such cases, the proper location of the riser is decided.

5. Placing of riser at the correct location is necessary to feed the melt to the desired locations within the casting.

a) True

b) False

Answer: a

Explanation: In casting system, riser is provided to compensate the liquid and solidification shrinkage during solidification of the casting in the mould. But to feed the melt at desired locations within the casting, it is very important to identify the correct location on the casting system to set up the riser mechanism.

6. A large size of riser should be placed on the casting system to compensate the solid shrinkage of the casting.

a) True

b) False

Answer: b

Explanation: In the solid shrinkage of the casting, casting cannot take any molten metal from the riser, as the casting is almost solidified. So, riser has no application for the solid shrinkage of the casting. To compensate the solid shrinkage, pattern of large size is placed in the mould which called a pattern with shrinkage allowance.

7. Which of the following formulas is used for the calculation of shape factor for complex casting in risering system?

a) /h

b) (l 2 + w)/h

c) (l 2 – w)/h

d) /h

Answer: d

Explanation: In tedious calculation for a complex casting, a method is used which gives different risering curve than the conventional method of area to volume ratio. In this method, the shape factor /h is used instead of , where l, w, and h denotes the maximum length, maximum width and the maximum thickness of the casting respectively.

8. The allowable thermal gradient generally depends on the shape and size of a cross-section of the casting.

a) True

b) False

Answer: a

Explanation: The thermal gradient within the casting is the most important factor during the last stage of cooling of casting. The minimum allowable thermal gradient generally depends on the shape and size of a cross-section of the casting. So to set up the risers in the casting system, area to volume  ratio of the casting is considered.

9. It is always desirable to have a large volume of molten metal in the riser to make casting products.

a) True

b) False

Answer: b

Explanation: The riser basically represents waste metal that is to be separated from the casted part and re-melted to make other castings. It is always desirable to have a minimum volume of molten metal in the riser to make efficient production of castings. This increases the casting yield which saves metal and reduces the time of production too.

10. In casting system, the riser is generally placed at the heaviest section to avoid defects from the casting.

a) True

b) False

Answer: a

Explanation: In the casting system, the risers must be placed at the heaviest sections to obtain better casting free from defects. And because the heavier sections, themselves act as feeders for the thin sections of the casting, and variations in the volume of riser should be done if the shape and size of casting sections also vary.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Residual Stress”.

1. Residual stresses are also known as locked-in stresses.

a) True

b) False

Answer: a

Explanation: Residual stresses or locked-in stresses are defined as the stresses existing within a body in the absence of external loading or thermal gradients. In other words, residual stresses in a material or component are those stresses which exist in the body without the application of any other external loads or forces.

2. Manufacturing process is the only consideration which can cause residual stresses in the casting.

a) True

b) False

Answer: b

Explanation: Manufacturing process is not only the single consideration which can cause stress. Residual stresses may be present in any mechanical component because of many causes. Residual stresses can be due to the technological process used to make the parts of casting, but manufacturing processes are the most common causes of residual stress.

3. Localized yielding of material can also be the reason for the generation of residual stresses in the casting.

a) True

b) False

Answer: a

Explanation: Localized yielding of material can induce residual stresses in the casting, because of a sharp notch or from various surface treatments like shot peening or surface hardening. To relieve residual stresses from the casting. Usually, heat treatment of the casting is done which also enhances mechanical properties in the casting product.

4. Residual stresses can cause any defects in the casting except distortion of the casting component.

a) True

b) False

Answer: b

Explanation: Residual stresses can be sufficient to cause any defects in the casting. It can split the metal part into two or more pieces abruptly without any application of external load or force. Residual stresses can also result in distortion of the casting component, which cannot regain its original shape easily.

5. Residual stresses can also be calculated the same way as the stresses due to the external loads is calculated.

a) True

b) False

Answer: b

Explanation: Residual stresses have the same role in a component’s strength as common mechanical stresses. However, the stresses due to external loads can be calculated with accuracy, but residual stresses are difficult to calculate. Therefore, it is very necessary to have a reliable method able to measure them with minimum damage to the surface of the casting.

6. The presence of residual stresses in a component can prevent failure of the casting component.

a) True

b) False

Answer: a

Explanation: Residual stresses may play an important role in explaining or preventing failure of a component at times. For example, shot peening of component to induce surface compressive stresses, in which residual stresses prevent failure and also improves the fatigue life of the component. But the internal or residual stresses should be kept balanced in the casting component.

7. By using resin bonded sand in the making of mould, the stresses produced in the casting can be reduced.

a) True

b) False

Answer: a

Explanation: By using resin bonded sand in the making of mould, the deformability of the mould and core is always improved which helps in reducing the internal stresses in the casting produced. The stresses are also reduced by increasing the holding time of casting in the mould, so as to reduce the difference in temperature distribution.

8. Natural aging treatment is a fast and accurate method for reducing residual stresses in the casting compared to the heat treatment.

a) True

b) False

Answer: b

Explanation: In natural aging treatment, generally the casting component is stored for several years to make the residual stress released slowly. This method takes long time and it is only suitable for the production of small-batch and larger casting components. And heat treatment does not take much of time depending on the type of heat treatment.

9. Machinability of the casting product can be improved by reducing the residual stresses in the casting.

a) True

b) False

Answer: a

Explanation: Reducing the casting of residual stresses can improve the machinability of the casting and increases tool life also. On the other hand, the castings machined after reducing the residual stresses have good dimensional stability, persistent precision and good reliability of the casting products.

10. Cold cracking failure of the casting product can be avoided by shot peening method which induces internal stresses in the casting.

a) True

b) False

Answer: b

Explanation: Cold cracking is basically caused by residual stresses exceeding the limitation of the casting’s strength. It normally appears at the tensile sites of the castings, especially at the sites of stress concentration. Shot peening method, instead of avoiding this defect, it increases the chances of cold cracking by inducing more stresses into the casting product.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Classification of Defects & Factors Affecting Salvage of Castings”.

1. Inspection of quality in a unit casting is much easier and beneficial, rather than inspecting it by separating the entire casting.

a) True

b) False

Answer: b

Explanation: It is very important to mention the correct qualifications of criterion usage of quality improvement tools. Separation of casting in parts takes place to investigate all the spheres of formation easily and usage of products to make an accurate inspection, but it may increase the time for inspection of castings.

2. The castings of minor defects can be salvaged economically without any high expense.

a) True

b) False

Answer: a

Explanation: The minor defects, which can totally allow the castings to be economically salvaged and leave a reasonable margin for the profit in a production of castings, but the major defects in the castings cannot be salvaged and results into the rejection of the casting and total loss of the production.

3. Which of the following is not part of an integrated management system in the production of casting?

a) Quality of production

b) Protection of environment

c) Casting yield

d) Safety in working conditions

Answer: c

Explanation: The quality of production, protection of environment, safety and protection of humans and machines in working conditions are integral part of management system. Integrated management system is the system which integrates management systems into one continuous system. Casting yield is another concept which does not considered in integrated management system.

4. The defects in the castings are majorly caused by the surrounding environmental conditions.

a) True

b) False

Answer: b

Explanation: The surrounding has negligible affects on the castings. The defects are majorly caused by unsuitable raw materials used in moulding, using improper tools, equipment, patterns. And sometimes faulty organization and lack of training for the workers can also lead to the inducement of defects in the castings.

5. The decision for rejection or replacement of casting is majorly considered with respect to the functioning of casting instead of defects in the castings.

a) True

b) False

Answer: a

Explanation: The decision for rejection or replacement of casting should be based upon not only the presence of defects in the casting itself but also on the significance in relation to the functioning or working of the casting product. This makes salvaging of casting products more easy and efficient.

6. Varieties or non-standardizing in the production of castings gives more safety and protection from the defects.

a) True

b) False

Answer: b

Explanation: In the production of casting components, close control and standardization of all aspects of technique give the best safety and protection against the inducement of defects in the castings. And it becomes easier to understand the laws and designs related to production by implementing standardization.

7. Defects like sand inclusion in the metal casting can lead to rejection of the whole casting.

a) True

b) False

Answer: a

Explanation: Sand inclusion is one of the most frequent causes for rejection of casting. It is very difficult to diagnose, as this type of defect normally occurs at varying positions in the casting which is caused by eroding of sand by a metal stream and then float to the surface of the casting. So it is not easy to attribute to a local cause.

8. In the case of steel castings, the salvaging operations are costlier than the conversion operations.

a) True

b) False

Answer: b

Explanation: In case of steel castings, the salvaging operation is preferred as a cost of salvaging is much cheaper than the total conversion, while in case of grey cast iron castings, sometimes the salvaging operations are costlier than the conversion process. Salvaging is only preferred when it is economical for the castings.

9. In proper design and working of the casting system, the salvaging operation can be avoided.

a) True

b) False

Answer: a

Explanation: Salvaging is one of the most costs affecting constituent and an avoidable operation. Salvaging can be avoided if the casting process takes place in the correct manner and according to the design considered. The success of the production of castings is indirectly proportional to the extent of salvaging carried out.

10. Electrodes are basically used in the process of salvaging which are more or less similar to the base composition of the casting.

a) True

b) False

Answer: a

Explanation: Despite the continuous technological growth, a certain percentage of castings always possesses imperfections that further cause defects in the casting product. The salvaging is always carried out using electrodes, whose composition is more or less similar to the base composition of the casting.

11. Which of the following is not a gas defect?

a) Blow holes

b) Run out

c) Pinhole porosity

d) Air inclusions

Answer: b

Explanation: Run out is not a gas defect, instead it is a moulding material defect.

12. Which of the following is a metallurgical defect?

a) Hotspots

b) Shrinkage cavities

c) Slag inclusions

d) Metal penetration

Answer: a

Explanation: Hot spots are a type of metallurgical defect. Occurs due to the chilling of the casting.

13. Dropping of loose moulding sand or lumps is responsible for which of the following defect?

a) Misruns

b) Cuts

c) Drop

d) Fusion

Answer: c

Explanation: Drop defect is caused when anything including loose sand and lumps drops from the cope into the drag portion of the casting.

14. Shrinkage cavities are compensated by ___________

a) Providing proper chill techniques to the casting

b) Providing proper feeding of liquid to the casting

c) Using specific risers

d) Using proper ramming during solidification

Answer: b

Explanation: Shrinkage cavities are formed due to volume decreasing phenomena while solidification of liquids. Proper liquid metal feed is given to reduce the effect of shrinkage.

15. Proper ramming is used to eliminate which of the following defects?

a) Swell

b) Run out

c) Pinhole porosity

d) Cuts and washes

Answer: a

Explanation: Heavy metallostatic forces cause the mould wall to move back and result in an increment in dimensions if the casting. Good ramming techniques are used to eliminate this defect.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Salvaging Techniques”.

1. Which of the following welding method is not used for salvaging?

a) TIG welding

b) MIG welding

c) Gas welding

d) Oxy-hydrogen welding

Answer: d

Explanation: In casting processes, there are many occasions on which a lot of material is wasted. Among the following, TIG welding, MIG welding and gas welding, are a few methods used in salvaging welding.

2. Which of the following is not a method of preparation of defective areas?

a) Chipping

b) Grinding

c) Rolling

d) Gouging

Answer: c

Explanation: In salvaging techniques, when a particular part has to be welded. Before the beginning of the weld, the defective part has to be prepared for it. Chipping, grinding and gouging are a few types of doing it.

3. Which of the following method is most suited for salvaging?

a) Brazing

b) Welding

c) Caulking

d) Plugging

Answer: b

Explanation: It is observed that, when the material which has been wasted, to be able to bring it to use, with the help of salvaging techniques, welding serves as the most appropriate operation than all others.

4. Which of the following is not an important property in terms of filler metals?

a) Thermal resistance

b) Chemical resistance

c) Corrosion resistance

d) Appearance

Answer: a

Explanation: When filler metals are considered, one has to be very careful while operating on it, as they play an important role in the weld characteristics. The thermal resistance has to be taken into account, but not as much as chemical resistance or corrosion resistance or the appearance of it.

5. Below what temperature does a solder melt?

a) 500°F

b) 600°F

c) 700°F

d) 800°F

Answer: d

Explanation: The process of soldering is very much similar to that of brazing, except for the temperature difference. In the soldering process, the solder gets melted, when the temperature goes below 800°F.

6. Which of the following is not an impregnant?

a) Linseed oil

b) Sodium silicate

c) Silicon carbide

d) Synthetic resin

Answer: c

Explanation: Caulking and impregnation are one of the techniques used for salvaging defective castings. Among the following, linseed oil, sodium silicate and synthetic resins are regularly used as impregnants, but not sodium carbide.

7. At what temperature, is sodium silicate immersed in the cast for salvaging?

a) 125°F

b) 175°F

c) 225°F

d) 275°F

Answer: b

Explanation: Sodium silicate is a type of impregnant, used for salvaging. The use of sodium silicate to immerse in the cast is termed as impregnation. The temperature at which this immersion should take place is between 175°F to 200°F.

8. For what time is a cast kept immersed in sodium silicate solution for salvaging?

a) 1 hour to 3 hours

b) 2 hours to 4 hours

c) 3 hours to 5 hours

d) 4 hours to 6 hours

Answer: b

Explanation: In impregnation technique of salvaging casts, the material has to be kept immersed inside the sodium silicate solution at a temperature between 175°F to 200°F, for about 2 hours to 4 hours.

9. Salvaging through welding is mainly focused on high alloy steels.

a) True

b) False

Answer: a

Explanation: Salvaging techniques, use the generated waste from casting processes in useful means by performing various operations on it like, welding, brazing and so on. Welding operation for salvaging is most suited for high alloy steels and more to iron.

10. Filling can be used for non-ferrous alloys.

a) True

b) False

Answer: a

Explanation: There is some sort of preparation required to the defective parts of the metal before it is put for welding. When non-ferrous materials are to be prepared, filling serves as an option, before it is welded. Grinding is also one of the options for preparing non-ferrous materials.

This set of Casting Questions & Answers for Exams focuses on “Salvaging Techniques – 2”.

1. Which of the following parts of castings are mostly salvaged with defective cast cooling bumps?

a) Piston

b) Cylinder

c) Connecting rods

d) Gas turbine parts

Answer: d

Explanation: In salvaging of gas turbine castings, parts are exposed to the one side where high-temperature fluid medium has cast-in bumps on an opposite cooling surface side to increase heat transfer rate. This makes uniform cooling of the casted product to have negligible defects in the casting.

2. In salvaging of castings, cooling fluid used can be directly exposed to the hot castings to enhance heat transfer.

a) True

b) False

Answer: b

Explanation: A cooling medium like coolant air from the compressor or steam is commonly directed to the casting along one or more casting surfaces. This flow for cooling is considered as backside flow, where the cooling medium is not directly exposed to the high temperature of surfaces of the casting.

3. A metallic powder is basically used as a coating for the heat transfer enhancement.

a) True

b) False

Answer: a

Explanation: A coating containing particles such as metallic particles or its powder is applied to the defective area. This sets in intimate contact with the area and brazed by an electric arc wire sprayed thermal process. The selected size of metallic particles depends on the provided heat transfer enhancement.

4. Which of the following types of inspection is mostly used for the identification of cast bumps on the castings?

a) Radiography

b) Eddy current method

c) Visual inspection

d) Dimensional inspection

Answer: c

Explanation: The surface areas of casting manifested by one or more partially cast bumps are first identified by visual inspection or sometimes by thermo-graphy. After identification, the areas are cleaned and the defective bumps are removed by the machining operations like grinding and grit blasting.

5. In salvaging process, the metallic particles used for enhancing heat transfer may stick to the surface areas of casting by melting itself.

a) True

b) False

Answer: b

Explanation: In the salvaging process, the metallic particles are always chosen to withstand the casting operating conditions while providing a high thermal conductivity that enhances heat transfer. The metallic particles must withstand the casting or part operating temperature while not diminishing other part properties.

6. In electric arc wire spray process, the atomizing air pressure is the only significant variable for controlling the surface layers.

a) True

b) False

Answer: a

Explanation: Electric arc wire spray process normally used within the ranges of about 100-500 amps of electric current and an air pressure of about 1.3-5.5 bar to atomize the molten wire metal and to propel droplets into contact with the defectively cast areas. And the atomizing air pressure is the only significant variable for controlling the surface layers of castings.

7. In salvaging of castings, the metallic powder coating can improve the heat transfer by_____

a) 5-10%

b) 10-30%

c) 30-50%

d) 100%

Answer: c

Explanation: In order to boost heat transfer by salvaging of castings, the average coating thickness of metallic particles must be at least about 0.2 mm and less than about 0.4 mm. This metallic coating provides 30-50% improvement in heat transfer which forms the casting defects free and highly efficient.

8. Without knowing the conditions or details about the castings, salvaging can even destroy or damage the whole casting.

a) True

b) False

Answer: a

Explanation: When approaching casting repair or salvaging, it is very important to know exactly which are the material and the condition of the object. By trying any welding or another procedure without sufficient previous information about the casting, it may damage or destroy the whole casting.

9. By using electric arc wire spray process, salvaging of white cast iron becomes very easy.

a) True

b) False

Answer: b

Explanation: In electric arc wire spray process, welding process is sought for casting repair or salvaging of a certain metal, the weld-ability of the casting metal should be good enough to accomplish the salvaging process. But in the case of white cast iron, it has no weld-ability that means it cannot be salvaged by having electric arc wire spray process.

10. In electric arc wire spray process, preheating of metal before welding is mainly done to prevent surface cracking.

a) True

b) False

Answer: a

Explanation: In salvaging of the casting metal, the weld-ability may depend on special techniques. For example, preheating before welding is mainly done to prevent cracking due to thermal stresses and to reduce residual stresses, distortion and hardness of the casting metal. This makes electric arc wire spray process easy and reliable.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Mechanization”.

1. Mechanization basically deals with computer technology and electronic data processing that replaces human labour with machines.

a) True

b) False

Answer: b

Explanation: Mechanization is actually based on the machinery and equipment that ensures high accuracy and speed of operation, and automation is the one which deals with computer technology and electronic data processing that replaces human labour with high tech machines. In mechanization, the equipment is utilized to boost the production of castings.

2. In mechanization of foundry processes, zinc based alloys have less application due to their low structural stability.

a) True

b) False

Answer: a

Explanation: Zinc based foundry alloys with aluminium content have high strength and good tribiological properties, but due to their low structural stability over a long time that restricts their wider application in modern areas in the mechanization of foundry processes. This also reduces ductility due to the formation of dendritic structure.

3. Defects-less casting is the main consideration in mechanizing a foundry.

a) True

b) False

Answer: b

Explanation: The first main consideration in mechanizing a foundry is the investment that must yield a profit. Not only the cost of castings should be reduced, but the additional return on the investment should be enough to fulfill all the demand of an organization. And properties of casting are considered as secondary in mechanization.

4. The economic success in the production of castings is mainly depended on the demand for a product.

a) True

b) False

Answer: a

Explanation: Even after having expensive mechanization in foundry of castings, it has been studied in the all of its financial aspects that its economic success mainly depends to the existence of a great demand that is enough to justify the increased output in the production of castings, which directly indicates high productivity in an organization.

5. The transportation cost of casting is generally less as compared to the cost of mechanization.

a) True

b) False

Answer: b

Explanation: It is very important for an organization to have the initial capital for implementing mechanization. But, even though a foundry through mechanization may produce a certain casting at a cheaper price and much of the price of casting is in the form of transportation cost from foundry to the place of use.

6. In the mechanized foundry, the breakdown of one part of a producing unit may affect the entire production.

a) True

b) False

Answer: a

Explanation: In the mechanized foundry, when a part or component of machine fails or collapses, the entire production of castings can be disturbed. This is the only main drawback of mechanization in comparing with manual working for production. To avoid this drawback, all machine parts should have proper maintenance.

7. The maintenance cost in mechanized foundry is also cheap as the cost of castings produced by mechanization.

a) True

b) False

Answer: b

Explanation: A mechanized foundry always produces castings of cheaper cost than any other foundry. But lacks of maintenance can results into low productivity because in the maintenance of expensive equipment requires specially trained maintenance men which basically results in high cost of maintenance.

8. In mechanized foundry, rubber conveyor cannot be used for long time during production of castings.

a) True

b) False

Answer: a

Explanation: Difficulty arises by virtue of high temperature of the molten metal and its liquidity, spilling of the melt during pouring may freeze the roller conveyor. In the few instances when rubber conveyors have been tried, they were immediately discarded when a spillage of molten metal burnt the conveyors apart.

9. In sand moulding, the thickness of sand mould and bond strength should be high as much as possible to avoid sand inclusion in machine parts.

a) True

b) False

Answer: b

Explanation: High bonding strength of sand in mould mixture and its thickness does not avoid the problem of sand inclusion in machine parts greatly, and even this reduces permeability of moulding mixture in a great amount which results into the formation of castings with defects like blow holes.

10. Using sand in mould mixture can cause problems to machines in the mechanized foundry.

a) True

b) False

Answer: a

Explanation: Dust content of the air is generally kept low in some modern foundries, thus reducing the hazards to the workers. In sand moulding, the sand might get into the bearings of a roller conveyor or the moving parts of machines. Many foundry machines breakdowns due to the presence of sand or dust in the air.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Mechanized Foundry”.

1. In the mechanized foundry, a roller conveyor is used for the transportation of moulds, on which moulds are transferred by rolling.

a) True

b) False

Answer: b

Explanation: The transportation of the moulds should be controlled. A mould cannot be placed on a roller conveyor and allowed to roll until it is stopped by any obstruction. For transportation, moulds are either conveyed on trains or remained in permanent flasks or pushed mechanically along a roller conveyor.

2. In sand handling system, the moulds are generally taken out in shaking manner.

a) True

b) False

Answer: a

Explanation: In sand handling system of mechanized foundry, the moulds are taken out in a shaking manner that will allow the sand to be transported back to the conditioning plant through the conveyor belt. In this method, the process is easily accomplished without going into the various methods of sand handling.

3. In the mechanized foundry, rubber coated chills are used for supporting the cores in the mould system.

a) True

b) False

Answer: b

Explanation: The chills are coated with a rubber compound and in some special cases are sprayed with fine silica sand. These chills are basically used to promote solidification in a particular portion of the casting system, while for supporting the cores, the chaplets are used which placed in the mould space.

4. In the mechanized foundry, using of synthetic sand in moulding makes a casting of better quality.

a) True

b) False

Answer: a

Explanation: The sand handling system and the use of synthetic sand in mould mixture of mechanized foundry improve the quality of castings. The bonding strength and the permeability balances itself in an optimum way that gives mould of high strength and good refractoriness that results in castings of better quality.

5. Operating cost involved in the mechanized foundry is more than the cost of any other simple foundry for large production of castings.

a) True

b) False

Answer: b

Explanation: Implementation of mechanization in any foundry increases the production rate and also reduces the operating cost in large volume production of castings. In mechanized foundry overall cost except for maintenance cost decreases and the process takes place in less time too with high accuracy.

6. Mechanization also standardizes the working and equipment used in the production of castings.

a) True

b) False

Answer: a

Explanation: Mechanization standardizes almost all the processes and equipment involved in the production of castings. For example, use of standard sized flasks has the capability of storing a wide variety of flasks. This makes less variety in the production process and also makes easier for workers to understand the work.

7. In the mechanized foundry, insertion of cores in mould is very easy and normally done with high tech machines.

a) True

b) False

Answer: b

Explanation: In mechanized foundry, insertion of cores in mould is not easy. Cores, which are an important part of every mould, should still be inserted into the moulds manually. It is a very important drawback in mechanized foundry, the insertion of the cores remains as a strenuous operation.

8. Mechanization can eliminate the use of moulding machines in a foundry.

a) True

b) False

Answer: a

Explanation: By implementing mechanization in production, it can eliminate the application of moulding machines which reduces the amount of maintenance expense associated with the production of castings. This also terminates the use of other idle machines that results in optimization and saving of large capital.

9. In the mechanized foundry, removal of casting from mould is not easy and it is generally performed manually.

a) True

b) False

Answer: b

Explanation: In a mechanized foundry, castings are knocked out from the moulds on a vibratory grid at the knock outstation and sand passes down into a hopper through the grid, and then the castings vibrate off into the cooling trays. This makes the removal very easy with less effort and without damaging the castings.

10. In the mechanized foundry, which of the following parts is used for suspending the ladle during pouring of molten metal?

a) Runner

b) Gate

c) Sprue

d) Crane

Answer: d

Explanation: In foundry, the assembly of moulds and cores on a conveyor are carried to the casting station where the liquid metal is poured by the ladle which is suspended by the application of crane, and then moulds filled with liquid metal are cooled as they pass through the cooling tunnel and at last arrive at the knockout station for extraction of castings.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Processing Steps in Mechanized Foundry”.

1. By implementing mechanization in vacuum moulding, it forms better castings with good reliability.

a) True

b) False

Answer: b

Explanation: Vacuum moulding is very different from other types of a moulding process. In this method, water is not used in mould mixture that reduces chances of defects in the castings. But, the processes involved in vacuum moulding are very slow and this method cannot be adaptable to mechanization.

2. Mechanization can be the reason for creativity and involvement in working for the production of castings.

a) True

b) False

Answer: a

Explanation: By mechanization and modernization in the production of castings, fatigue and strain on the workers considerably reduce during working, and work culture also improves itself tremendously. Efficient working in production can lead to a sense of participation, involvement, and creativity.

3. In the mechanized foundry, the process of solidification is done manually and it is not affected by any tool of mechanization.

a) True

b) False

Answer: b

Explanation: In the mechanized system, tools help to simulate the casting solidification during processing. It enables the way to design the casting correctly and hence to avoid defects like hot spots and also to identify and indicate the stress concentration zones. It provides temperature history of castings, detailed information on the temperature contours inside the solidifying casting.

4. Which of the following parts is used for cleaning the castings in a mechanized foundry?

a) Magnetic roller

b) Spherical roller

c) Scrubbing cylinder

d) Steel balls

Answer: c

Explanation: When casting passes over a vibrating screen are generally conveyed to a self clearing scrubbing cylinder. In this rotating cylinder, castings are tumbled and sprayed with water so that they emerge from the process cool enough for the certain inspection and transportation on a rubber belt.

5. The method of scrubbing or cleaning cannot be used for excessively large castings in a mechanized foundry.

a) True

b) False

Answer: a

Explanation: The method of scrubbing or cleaning is mainly used for removing the gates from the casting; this process uses a scrubbing cylinder which cannot be used for excessively large castings because this process tends to crack the smaller parts of the casting. So, special techniques or more labours are employed for the process.

6. In the mechanized foundry, the process of breaking gates may crack or damage the castings parts.

a) True

b) False

Answer: b

Explanation: In the mechanized foundry, the gates are break off from the castings without any subsequent damage to the casting part itself. This is achieved by redesigning the gates practically from all of the patterns so that the cross-section of the gate reduces enough to enable it to break off at that point without damaging the casting.

7. Sand with high bond strength can lessen the amount of moisture in mould of a mechanized foundry.

a) True

b) False

Answer: a

Explanation: In the mechanized foundry, use of sand with more bond strength can lessen the moisture content in the mould mixture, or additional sand storage capacity can also enable the sand to cool that might eliminate the moisture problem in the mould. Moisture content should be kept balanced in mould making process.

8. Mechanization can also manipulate the fundamental laws related to the production of castings.

a) True

b) False

Answer: b

Explanation: The methods and techniques involved in mechanized foundry for production of castings can change considerably, but the metal casting is the oldest manufacturing process, so the fundamental principles or laws associated with the manufacturing remain almost the same in the process.

9. In the mechanized foundry, almost all the processes involved in production aims to achieve castings of better quality.

a) True

b) False

Answer: a

Explanation: Casting quality is considered as an important parameter, this basically satisfies the customer requirements. To achieve and maintain quality in production, it is very necessary to control the production process firstly. Manual control cannot fulfill to attain the expected quality of castings. So, mechanization or modernization is introduced to manage and control the process efficiently.

10. Mechanization is not suitable for small type production due to consumption of excessive power by the processes involved in a mechanized foundry.

a) True

b) False

Answer: a

Explanation: Mechanization is only suitable for mass production because the initial cost, power usage, and maintenance costs involved are very higher than any other method. Small type production will not be profitable in a mechanized system. So, a large type of production should have mechanization for high productivity.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Molding Machines”.

1. Which of the following is not a process of ramming?

a) Squeezing

b) Quenching

c) Jolting

d) Slinging

Answer: b

Explanation: Ramming of sands is considered to be one of the most important operations of molding machines. Ramming is done in a molding box. A few types of ramming operations are, squeezing, jolting, slinging and blowing.

2. Which machine is most useful for making shallow patterns?

a) Squeeze machine

b) Sand slinger

c) Jolt-squeeze machine

d) Jot-squeeze roll over

Answer: a

Explanation: In a squeeze machine, there is a squeezer head or a plate which is used as a pressing board to force the sand inside or compress it. This machine is mostly used for shallow patterns.

3. Which of the following is not a power operated molding machine?

a) Squeeze machine

b) Sand slinger

c) Jolt-squeeze machine

d) Jot-sand machine

Answer: d

Explanation: In the power operated molding machines, there is a use of compressed air and hydraulic machinery. There are also electromagnets used in it. These machines are classified as, squeeze machine, sand slinger, jolt-squeeze machine and sand slinger.

4. At what pressure, does the compressed air enter in squeezing machine?

a) 6 kg/cm 2

b) 7 kg /cm 2

c) 8 kg /cm 2

d) 9 kg /cm 2

Answer: b

Explanation: In squeezing machines, the sand used is rammed very hard. It has a greater density at the surface than at the interiors. The air required for compression of the sand, enters at 7 kg /cm 2 .

5. Up to what depth of molds is a squeezing machine used?

a) 10 cm

b) 12 cm

c) 15 cm

d) 18 cm

Answer: c

Explanation: It is considered among one of the limitations of squeezing molding machines, that they can only be used if the mold is shallow. The depth up to which a squeezing molding machine can be used is 15 cm.

6. With an increase in the diameter of the piston, how does the molding force change?

a) Increases

b) Decreases

c) Does not change

d) Not related

Answer: a

Explanation: The force needed for molding is directly related to the square of the diameter of the piston, that is, with an increase in the diameter of the piston, there will be an increase in the molding force.

7. With a decrease in the length of the jolt stroke, how will the power of jointing be affected?

a) Increases

b) Decreases

c) No affect

d) Entities not related

Answer: b

Explanation: In a jolting machine, a cylinder and piston mechanism is present. The power of jolting is directly linked the length of the jolt stroke, which means, with a decrease in the length of jolt stroke, there would be a decrease in the jointing power.

8. With an increase in the jolted area, how does it affect the jolted length?

a) Increases

b) Decreases

c) No change

d) Not related

Answer: b

Explanation: According to the formula of power required for jolting, the jolted area is inversely related to the length of the jolt stroke, that is, with an increase in the jolt stroke, there will be a decrease in the jolted area and vice versa.

9. Hand molding is an inexpensive process.

a) True

b) False

Answer: a

Explanation: Hand molding operation need a lot of time for completion and labor effort, but, in case of molding machines, the equipment needed are costly, making the overall process an expensive one.

10. High amount of tapering allowance is required when molding machines are used.

a) True

b) False

Answer: b

Explanation: In other types of castings, a tapering allowance of at least 3 o to 10 o is required to be given. But, when the entire process gets mechanized, the tapering allowance can be reduced, and much allowance is not required.

11. In the following squeezing machine apparatus, what does the question mark represent?

casting-questions-answers-molding-machines-q11

a) Diaphragm

b) Plate

c) Pattern

d) Flask

Answer: c

Explanation: In squeezing machines, the operations are made to happen under some amount of pressure. In this figure, the pattern is kept with the sand beneath it. This pattern therefore will experience the upward force.

12. In the following squeezing machine apparatus, what does the question mark represent?

casting-questions-answers-molding-machines-q12

a) Flask

b) Pattern

c) Pressure column

d) Plate

Answer: a

Explanation: In a squeezing operation mechanism, there is some amount of sand in the apparatus which is pressurized. This sand is accumulated and not allowed to spread away with the help of the flasks situated at the ends.

13. What is the minimum pressure required to be given in a squeezing process?

a) 4 kg/cm 2

b) 5 kg/cm 2

c) 6 kg/cm 2

d) 7 kg/cm 2

Answer: c

Explanation: In squeezing processes, there is piston used which applies a thrusting force over the sand beneath it. There is air present which gets pressurized in the system. This air pressure, minimum has to be 6 kg/cm 2 .

14. In the following squeezing machine apparatus, what does the question mark represent?

casting-questions-answers-molding-machines-q14

a) Plate

b) Air column

c) Diaphragm

d) Pattern

Answer: a

Explanation: In this figure, the question mark represents the plate. In the squeezing process mechanism, there is a plate involved for taking the load from the piston and transferring it on to the sand and air present there.

15. What is the maximum pressure required to be given in a squeezing process?

a) 6.5 kg/cm 2

b) 7.5 kg/cm 2

c) 8.5 kg/cm 2

d) 9.5 kg/cm 2

Answer: b

Explanation: A molding force is applied with the help of a piston in squeezing machines. This causes the air to get pressurized. This minimum pressure of the air can be 6 kg/cm 2 and the maximum air pressure can be 7.5 kg/cm 2 .

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Core Making Machines”.

1. In core making operation, core sand without binder and moisture is used to increase hardness.

a) True

b) False

Answer: b

Explanation: In the core making process, core sand is used which is also known as oil sand. It is high rich silica sand that blends with oil binders such as core oil which is a combination of linseed oil, resin, mineral oil and other bind substances. Flours and water can also be used in making of large cores which is a very economical way.

2. Cores can be made within the mould by using moulding sand which is used for mould preparation.

a) True

b) False

Answer: b

Explanation: The cores are compact mass of core sand which is a special kind of sand. And cores are always prepared separately and then placed in mould cavity at a required location with proper alignment and accuracy. Core does not allow the liquid metal to occupy space for solidification in that part and hence help to produce hollowness in the casting component.

3. The permeability of core sand is generally kept higher as compared to that of moulding sand in core making operation.

a) True

b) False

Answer: a

Explanation: In the core making process, the permeability of the core sand should be sufficiently high as compared to that of the moulding sand. So the core gases easily escape through the area of the core recesses which is generated by the core prints. And the core sand should also be of highly refractoriness in nature to sustain high temperature of molten metal.

4. Better collapsibility of core sand in core making process can ease the cleaning of castings.

a) True

b) False

Answer: a

Explanation: The core sand must be collapsible in nature, i.e. it should be disintegrate easily after the metal solidifies in the mould cavity, this property can ease the cleaning of the castings. For a sufficient degree of collapsibility, adequate core binders should be used in core making process which also increases strength of core.

5. Inorganic type of core binders is generally preferred as compared to organic core binders in core making procedure.

a) True

b) False

Answer: b

Explanation: In general, the binders are present as inorganic as well as organic ones, but for the core making process, organic binders are normally preferred because they are combustible and can be easily destroyed by the heat at high temperatures thereby providing the sufficient collapsibility to the core sand.

6. Which of the following materials is used for imparting strength and collapsibility in core sand during core making process?

a) Molasses

b) Core oil

c) Sulphite binder

d) Thermo-setting resin

Answer: d

Explanation: Thermo-setting resin is very popular in core making because it imparts high strength, collapsibility to core sand and it also emits a minimum amount of mould and core gases which can produce defects in the casting component. The most general binders under this category are phenol formaldehyde and urea formaldehyde.

7. Uniform and homogenous mixture of core sand can be achieved by manual operation.

a) True

b) False

Answer: b

Explanation: Preparation of uniform and homogenous mixture of core sand cannot be possible manually. So for better and uniform core sand properties using proper sand constituents and binders, the core sands are generally blended with the help of roller mills or core sand mixer which uses vertical revolving arm type and horizontal paddle type mechanisms.

8. In core blowing machines, the filling of core sands in core boxes is done by using compressed air.

a) True

b) False

Answer: a

Explanation: The basic principle of core blowing machine constitutes of filling the core sands into the core boxes by using compressed air. The velocity of the air is kept high to get a high velocity of core sand particles that ensures their deposit in every corner of the core box. On entering of core sand with high velocity, the shaping and ramming of core are performed simultaneously in the core box.

9. In core sand preparation, roller mills are suitable for core sand that contains only a single binder called cereal binders.

a) True

b) False

Answer: a

Explanation: In the case of roller mills, the rolling function of the mulling machine along with the turning over movement caused by the ploughs gives a satisfactory and homogeneous mixing of core sand. Roller mills are only suitable for core sands that contain cereal binders, whereas the core sand mixer can be suitable for all types of core binders.

10. A low viscous fluid as lubricant is basically used for extraction of cores from the core boxes.

a) True

b) False

Answer: b

Explanation: After ramming of sand, the core box is put on a core plate supported by the machine bed. A rapping action is generated on the core box by vibrating a vertical plate. This rapping action helps in extracting the core from the core box. After rapping the core box, the core is pulled up and gets onto the core plate.

This set of Casting Quiz focuses on “Foundry Environment Health and Safety”.

1. Above what noise levels should hearing protector be worn by a worker?

a) 80 dB

b) 85 dB

c) 90 dB

d) 95 dB

Answer: b

Explanation: Hearing protectors are one of the most important tools of safety measures. Every employee who works in a foundry, in a noise level above 85 decibels should wear a hearing protector as a safety measure.

2. Above what period of employment should a person wear a hearing protector?

a) 3 months

b) 6 months

c) 9 months

d) 12 months

Answer: b

Explanation: Industrial noises are of very high frequencies, any sound of such decibels can cause deafening to the employee if he is working for a long period of time. For any employee who is working for more than 6 months should wear a hearing protector.

3. What is the shape of an ear canal seal?

a) Spherical

b) Cylindrical

c) Conical

d) Pyramidal

Answer: c

Explanation: Ear canal seals are a type of hearing protectors which help in reducing the noise level heard by the employee. These are an option to plug type protectors. The shape of ear canal seals is conical.

4. Which of the following is not a source for entering phenols?

a) Steel scrap

b) Coke combustion product

c) Sand binder

d) Scrap iron

Answer: a

Explanation: There are many types of compounds which contain mainly phenolic components in them. These compounds are present in the foundry environment, which may cause damage to human health. Among the following, steel scrap is not a source for entering phenols.

5. Which material is used for destroying phenols?

a) Carbon tetrachloride

b) Carbon dioxide

c) Carbon monoxide

d) Chlorine dioxide

Answer: d

Explanation: In a foundry environment, there is a presence of phenols observed coming through various sources like scrap iron. These phenols can be destroyed with the help of a compound called as chlorine dioxide.

6. What is the allowable time exposure for an air blow noise?

a) 2 hours

b) 3 hours

c) 4 hours

d) 5 hours

Answer: a

Explanation: It is the noise experienced in quick released high pressure air that 4 hours of time can be allowed to be exposed to it. But in case of air blow noise, allowable exposure is only 2 hours.

7. What is the amount of noise produced in hand ramming with a hammer?

a) 90 dB

b) 95 dB

c) 100 dB

d) 105 dB

Answer: b

Explanation: In case of sand slingers, 90 dB of noise is produced. In the case of tumblers, 100 dB of noise is produced. In case of shake out, 105 dB of noise is produced, and in case of hand ramming with hammers, 95 dB of noise is produced.

8. What is the maximum amount of phenol concentration found in a foundry?

a) 3 ppm

b) 4 ppm

c) 5 ppm

d) 6 ppm

Answer: c

Explanation: In foundries, there are many ways by which phenol compounds enter into the working space. High amount of phenol concentration could be hazardous for human health. The maximum amount of phenol concentration found in foundries is 5 ppm.

9. Gloves used in foundries are made up of copper fabric.

a) True

b) False

Answer: b

Explanation: In foundries, gloves are used for the protection of the hand of the worker. These gloves are made up of aluminized fabric, which helps in reflecting the heat. They also contain a material called asbestos, which provides insulation.

10. Cape sleeves cover the knee of the worker.

a) True

b) False

Answer: b

Explanation: A pourer’s legging and a knee legging is used for covering the knee, ankle and the lower part of the leg. A cape sleeve, on the other hand, is used for covering the shoulder, the back, the chest and the arm of the worker.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Foundry Environment Health and Safety – 2”.

1. In working at the foundry, the risk of getting injuries is inversely proportional to the frequency of exposure to the worker.

a) True

b) False

Answer: b

Explanation: Health effects or injuries can occur if a worker is exposed to the hazard which is basically a potential for a process to do harm. The risk of getting injuries generally increases with the duration and frequency of exposure to the worker in the foundry. So, proper equipment with care should be used for working in a foundry.

2. Improper controlling of hazards in the foundry can lead to the occurrence of serious health problems to the workers.

a) True

b) False

Answer: a

Explanation: The processes involved in the production of castings gives rise to heat, liquid metal splashes, dust, noise, vapours and toxic gases in the foundry environment. If these hazards are not controlled properly in the foundry, then the serious health problems can occur to the workers badly.

3. Which of the following hazards presence in the foundry is responsible for lung disease to the workers?

a) Noise

b) Metal splashes

c) Heat

d) Dust

Answer: d

Explanation: The airborne contaminant like dust can cause lung disease to the workers especially due to the presence of silica dust in the foundry. This silica dust is basically generated due to the processes such as mixing, moulding, shakeout and cleaning operations and also during sand conditioning.

4. To control dust in the foundry during casting processes, it is dumped or mixed with water to reuse it for the preparation of mould.

a) True

b) False

Answer: a

Explanation: The dust mainly arises from the sand particles. The efficiency of dust control, the chemical and the physical state of the sand which basically indicates whether the sand particles screened or unscreened, dry or wet, the used sand is either dumped or remixed with the water and binder to use it for preparation of mould.

5. Which of the following processes is used for recycling of silica sand or dust in foundry during the casting process?

a) Radiography

b) UV method

c) Abrasive blasting process

d) Finn method

Answer: c

Explanation: In foundry during the production of castings, abrasive blasting process generally involves the use of sand particles containing a high amount of free silica. The cleaned sand from the castings can also include silica hazard, metal dust which can be toxic, are recycled through the abrasive particles present in abrasive blasting machines.

6. In foundry during casting processes, carbon monoxide gas is produced only by the furnaces.

a) True

b) False

Answer: b

Explanation: In the foundry, carbon monoxide gas is produced in abundant amounts by the presence of furnaces. It can also be produced during the pouring of liquid metal. Inhaling of carbon monoxide gas restricts the blood from carrying a normal supply of oxygen. This further causes headache, nausea, and other health related problems.

7. Which of the following operations in the production of castings gives rise to excessive noise in the foundry?

a) Pouring

b) Shakeout

c) Coating

d) Melting

Answer: b

Explanation: In foundries during the production of castings, operations like dressing, fettling and shakeout give rise to significant noise levels with potentially adverse effects on the hearing of foundry workers. Shakeout operation basically includes extraction of casting from the mould cavity by using a vibrating plate which is the main source of noise in the foundry.

8. Protective cloths are worn by the workers to resist the radiation of heat in the foundry.

a) True

b) False

Answer: a

Explanation: Radiation of heat is the major source of heat or thermal load which is imposed onto the workers. To protect themselves, Protective cloths are worn by the foundry workers to resist the radiating heat from the heat sources. The workers experience a total thermal load which is obtained by the time spent in the foundry.

9. Casting of non-ferrous alloys by continuous casting method can cause an explosion if the casting contacts with water during processes.

a) True

b) False

Answer: a

Explanation: During the casting of non-ferrous alloys like copper and aluminium by continuous casting method can explode the casting violently if it contacts water. Such explosion can splash molten metal onto the foundry workers which might cause serious physical injuries. To avoid such type of violent explosions, great care should be taken by following the given instructions strictly.

10. The study of ergonomics basically does not require as almost the entire foundry operations are performed by automation or mechanization.

a) True

b) False

Answer: b

Explanation: Even after having great mechanization or automation in the foundry, various foundry operations like lifting, carrying and stacking of bulky objects are done manually which requires human workers. So, attention must be given to the ergonomic concept or principles and the correct methods of manual handling must be followed.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Dust Measurement and Sampling”.

1. Which of the following equipment is used for determining the concentration of dust accurately?

a) Screener

b) Air Dryer

c) Jas Filter

d) Gravimetric sampler

Answer: d

Explanation: Gravimetric sampler is used for determining the concentration of dust, which provides a time weighted mean dust concentration. A special filter is used in this sampler which uses the analytical technique to determine silica content and also estimates an average dust concentration over the sampling stage.

2. For determining the concentration of dust, continuous sampling is carried out by manual means.

a) True

b) False

Answer: b

Explanation: For determining the concentration of dust, continuous sampling is carried out which uses automatic sensors, electrochemical, and spectroscopic methodology to produce continuous reports of concentration values of the dust particles. The particular time means concentration values can then be determined by the continuous reports.

3. Which of the following sands can be used as a substitute for minimizing the dust particles in the foundry?

a) Core sand

b) Silica sand

c) Olivine sand

d) Quartz sand

Answer: c

Explanation: It can be essential to substitute less hazardous sand such as olivine sand which can reduce free silica concentrations and thus minimize the dust particles in the foundry. In this case, local exhaust ventilation must be provided at the mixing or mulling period as the sand used in the foundry is dry.

4. The biological monitoring of carbon monoxide is basically done by the blood sampling procedure.

a) True

b) False

Answer: a

Explanation: For the recognition and treatment of carbon monoxide poisoning, all the exposed foundry workers must be instructed. The biological monitoring of carbon monoxide can be done by blood sampling or by exhaled air samples that can also be an applicable method. The samples are mostly taken at the end of working time.

5. To examine health hazards and material damages in the foundry, the sampling site should be away from the source of pollution.

a) True

b) False

Answer: b

Explanation: Sampling sites generally controlled by the factors like objectives, technique of sampling and the resources available. To examine the health hazards and material damages, the sites should be kept close to the objects where the effects are being examined and should be kept at the breathing level in the foundry.

6. Mechanization in the foundry can reduce the level of dust which may further reduce the cost of sampling.

a) True

b) False

Answer: a

Explanation: By mechanization in a foundry, dust level can be reduced by using pneumatic conveying systems which transfers and feeds additives into the process area. This also includes enclosed conveyers with dust controlled transit points, especially for transferring sand into the moulding shops in the foundry.

7. Which of the following processes is responsible for the emission of particulate matter in the foundry?

a) Moulding

b) Melting

c) Dressing

d) Shakeout

Answer: b

Explanation: In the melting process of material in the foundry, particulate matter emissions in the form of dust and metal oxide fumes which generally varies according to the type of furnace, material to be melted and its characteristics. Most of the particulates like coke, rust and silica are produced by the cupola furnaces.

8. To measure and control dust particulates in the foundry, dry dust technologies are mostly preferred than the wet dust technologies.

a) True

b) False

Answer: a

Explanation: To measure and control dust particulates in the foundry, dry dust collection technologies like bag filters are commonly used instead of wet dust technology like wet scrubbers. The dry methods allow dust particulates to be easily collected, transported, and re-circulated to the mould preparing process.

9. In non-ferrous foundries, dust from the emission control equipment is considered as hazardous waste which cannot be recoverable.

a) True

b) False

Answer: b

Explanation: In non-ferrous foundries, dust from the emission control equipment can contain particulates like zinc, lead, nickel, cadmium, and other materials which classified as hazardous waste. But somewhat of materials can be recoverable from this waste, this is done by using filter dust which can allow metal recovery through dust reprocessing.

10. Respirable dust sampling is a method which uses a cyclone to separate and capture dust particles.

a) True

b) False

Answer: a

Explanation: Respirable dust sampling method uses a cyclone to separate and capture dust particles in the range of size. The respirable fraction is attained on a pre-weighed PVC filter which is used for gravimetric analysis. The size of dust particles and its characteristics are obtained by the type of cyclone used with the sampling flow rate.

This set of Casting MCQs focuses on “Dust Control and Dust Extraction in Foundry”.

1. What does LEV stand for?

a) Local Exhaust Ventilation

b) Limited Entry Ventilation

c) Local Entry Ventilation

d) Limited Exhaust ventilation

Answer: a

Explanation: The LEV stands for Local Exhaust Ventilation system. This system has a ventilation place in a downward direction with a turn table to help manipulate the castings.

2. Which of the following would not be counted among foundry dust?

a) Bentonite

b) Silica

c) Iron

d) Sea coal

Answer: c

Explanation: Among the following, bentonite, silica and sea coal are the materials from which a considerable amount of dust is found to remain in the foundries. Iron is not a part of it.

3. What will happen if continuously fine sands are removed from the molding mixture?

a) Brittleness

b) Poor finish

c) Less elasticity

d) More ductility

Answer: b

Explanation: For controlling the sand, if the fine sand which is added in the molding sand is removed continuously, it may cause the casting to be formed with a poorer finish than desired.

4. Which disease is caused by the inhalation of silica sand?

a) Silver syndrome

b) Silicosis

c) Sillence syndrome

d) Sinus venosus

Answer: b

Explanation: Silicosis is caused by the inhalation of silica sand, which in crystalline form. The inhalation of this sand causes inflammation in the upper part of the lungs. The characteristics are shortness of breath and fever.

5. What is the average velocity at the slit in Owan’s Jet counter apparatus?

a) 100 m/s

b) 150 m/s

c) 250 m/s

d) 360 m/s

Answer: c

Explanation: The Owan’s Jet Counter works on very high velocity using a hand pump. The velocity of operation, of this apparatus is between 200 m/s to 300 m/s, which makes the average velocity of operation to be 250m/s.

6. What should be the width of the slit used in Owan’s apparatus?

a) 0.1 mm

b) 0.2mm

c) 0.3 mm

d) 0.4 mm

Answer: a

Explanation: In the Owan’s counter jet apparatus, the length of the slit should be only 10 mm. But, the width of the slit is very small, being only 0.1 mm.

7. What is the amount of clearance allowed between the slits and the collecting plate in Owan’s appartaus?

a) 0.5 mm

b) 1 mm

c) 2 mm

d) 3 mm

Answer: b

Explanation: In Owan’s apparatus, the amount of clearance that is allowed, in between the slits and the collecting plates is only 1 mm, the width for dust depository is only 70 micro meter.

8. Which of the following cannot be a way of spreading dust?

a) Enclosing the mixer

b) Screening the sand

c) Moistening the sand

d) Treating the cast chemically

Answer: d

Explanation: For the prevention of spreading the dust, moistening and screening the sand can be options. By enclosing the mixer too sand spreading can be avoided. But by treating the cast chemically, its physical, chemical, as well as mechanical properties may change.

9. In pneumatic chisel, ventilation is applied through a duct over the operator’s hand.

a) True

b) False

Answer: a

Explanation: In pneumatic chisel, ventilation is applied through three places in the apparatus. A duct over the operator’s hand, a duct connected on the chisel side and a hollow chisel present.

10. In pneumatic chisel, what is the dust velocity normally?

a) 270 meters/min

b) 330 meters/min

c) 370 meters/min

d) 430 meters/min

Answer: c

Explanation: In pneumatic chisel, there is a vacuum created of up to 250 to 375 Hg. This enables the dust velocity to be around 370 meters/minute.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Dust Collecting Equipment”.

1. Which of the following types of filtration system uses an eccentric rod assembly?

a) Reverse air cleaning

b) Jet cleaning

c) Shaker filtration system

d) Pulse cleaning

Answer: c

Explanation: In filtering equipment, the filter bags are intermittently shaken by means of an eccentric rod assembly that can take place if the filtration process is obstructed. This cleaning method is generally used in smaller sized filter systems as the load has to remain low. In general, this cleaning method is not very optimal.

2. Improper application of dust collecting equipment may lead to the occurrence of dust explosion.

a) True

b) False

Answer: a

Explanation: In the foundry, when the dust is combustible and dispersed in air or another oxidant and improper using of dust collecting equipment which increases pressure in the dust compartment of equipment and thereby a thread of ignition due to increase in pressure and temperature can even lead to an explosion.

3. The chances of hazard increase with the increase in the size of combustible dust particles in the foundry.

a) True

b) False

Answer: b

Explanation: The chances of hazard increases due to a decrease in the size of combustible dust in the foundry. More particles in small size in a specific volume provide a larger area for combustion. The volatility of fine dust particles can easily propagate explosion by contacting ignition which might further cause dangerous physical injuries to the foundry workers.

4. A thorough analysis of combustible dust should be followed even after collecting it by dust collecting equipment.

a) True

b) False

Answer: a

Explanation: A thorough analysis should be considered in which dust can be disbursed. Dust is concentrated in equipment such as dust collectors; a combustible combination may be present whenever the equipment is functioning. After assessing hazards, mitigation techniques should be used in the situation to regulate the combustible dust hazards.

5. Ventilation systems can only control the temperature but cannot be used for controlling dust particles in the foundry.

a) True

b) False

Answer: b

Explanation: Ventilation systems are best for controlling air quality by preventing the flow of dust particles. The processes involved in this system are accomplished by mechanical or natural means. It can also control temperature but it is majorly considered for the controlling of air quality by collecting dust particulates.

6. Electrical equipment is also used along with the dust collecting equipment to control ignition of combustible dust particles in the foundry.

a) True

b) False

Answer: a

Explanation: In the foundry, the processes involved in the production of castings like melting, pouring and solidification generates combustible dust particulates which may even burst due to the presence of high pressure, which can cause explosion in the foundry. So, appropriate electric equipment and wiring methods should be used for controlling spark or ignition of dust particles.

7. In non-ferrous foundries, electrical equipment, heating system and dust collecting systems are generally kept in a single unit to optimize space.

a) True

b) False

Answer: b

Explanation: In non-ferrous foundries, there can be chances of a generation of combustive dust particulates which are safely collected by dust collecting equipment. But keeping of this system with heating system might ignite the dust particles which in turns to fire or explosion in the foundry. So it is very necessary to keep dust collecting systems away from the heating systems.

8. A fast acting valve is generally installed to isolate combustive hazards in the foundry.

a) True

b) False

Answer: a

Explanation: A fast acting valve is an isolating or segregating device used for isolating the hazards with a barrier. The purpose of this automatic fast acting valve is to seal off the area of material handling system from spreading of fire. It is intended to prevent the flame front and isolate the part of equipment in the case of rapid burning.

9. Which of the following devices is used for the removing of particulates from a gas by using water droplets?

a) Pulse cleaner

b) Air cleaner

c) Dry scrubber

d) Venturi scrubber

Answer: d

Explanation: Venturi scrubbers are used to remove dust particulate from the gas stream. Venturi Scrubber includes a venturi part in combination with a droplet separator part, where the gas is fed into the part and it proceeds through a water mist at the venturi throat at high speed. The dust particle mixes with water to form large particles that remove itself from the gas in the separator part.

10. In the dry gas scrubbing process, sodium bicarbonate material is used which completely absorbs the acidic gases and other dust particles.

a) True

b) False

Answer: b

Explanation: In dry gas scrubbing process, sodium bicarbonate adsorbent is used which adsorbs the acidic gases and other dust particles. The complete process is adsorption instead of absorption. Adsorption process, in which particles or exhaustive gases adheres to surface of adsorbent by forming an extremely thin layer of particulates to the adsorbent.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Elements of Preventive Maintenance”.

1. Which of the following is not an important condition for preventive maintenance?

a) Size

b) Age

c) Location

d) Oils used

Answer: d

Explanation: Whenever preventive maintenance is to be done, it has to be observed that, there is no major breakdown at the site. For this, there are certain factors which need to be taken into account, like, size and age of the machinery used, the location of the machine and the overall machinery.

2. What is the ratio of preventive maintenance and total maintenance in primary-metal industry?

a) 1 : 1.27 men

b) 1 : 2.17 men

c) 1 : 2.37 men

d) 1 : 3.17 men

Answer: c

Explanation: In various industries, the ratio of preventive maintenance to total maintenance differs according to the conditions prevailing there. When primary-metal industry is used, the ratio is 1 : 2.37 men.

3. Which of the following is not counted among safety equipment?

a) Vacuum reliever

b) Alarms

c) Flashback arresters

d) Temperature reliever

Answer: d

Explanation: Safety equipments play a very essential role in the industries, where the workers are vulnerable to many risks. A few of them are, vacuum and pressure reliever through valves, safety alarms and flashback and flame arresters, but not a temperature reliever.

4. What is the ratio of preventive maintenance and total maintenance in machinery-manufacturing industry?

a) 1 : 10 men

b) 1 : 2.69 men

c) 1 : 2.37 men

d) 1 : 3.77 men

Answer: b

Explanation: According to the various needs and type of works in different industries, the ratio of preventive maintenance and total maintenance differs. In a machinery manufacturing industry, the ratio is 1 : 2.69 men.

5. Which of the following is not a material handling equipment?

a) Cranes

b) Lifts

c) Tongs

d) Hoists

Answer: c

Explanation: When it comes to inspection of the preventive maintenance in an industry, the material handling equipments come very handy. Cranes, lifts, hoists, conveyors and trucks are a few of the examples of material handling equipment.

6. What is the ratio of preventive maintenance and total maintenance in general manufacturing industry?

a) 1 : 10 men

b) 1 : 2.69 men

c) 1 : 2.37 men

d) 1 : 3.77 men

Answer: a

Explanation: The ratio of preventive maintenance and total maintenance, in case of primary-metal industry, the ratio is 1 : 2.37 men, in case of machinery manufacturing industry, the ratio is 1 : 2.69 men and in case of general manufacturing industry, the ratio is 1 : 10 men.

7. Which of the following materials is not used as process equipment?

a) Furnace

b) Compressor

c) Pump

d) Generator

Answer: d

Explanation: During the inspection done in the preventive maintenances, there are certain equipment called as process equipment, which needs a little different inspection. A few of these are compressors, pumps and furnace.

8. Which of the following are not counted among periodic inspection?

a) Tear downs

b) Overhauls

c) Oil burnings

d) Replacement of parts

Answer: c

Explanation: There are many inspections counted under periodic inspection, namely, visual inspections, tear downs, overhauls and scheduled replacements of parts. The checking of oil burning comes under contingent working.

9. Preventive maintenance and its application is an expensive process.

a) True

b) False

Answer: a

Explanation: Preventive maintenances are not to be done very frequently, but it is advised, that, the preventive maintenance must be done at least once in the machines life. This imitation is caused due to very high costs of operation of preventive maintenance.

10. Frequency of inspection is decided on the basis of overloading.

a) True

b) False

Answer: a

Explanation: The frequency of inspection of the processes gets decided on the basis of many factors. A few of them are, stresses experienced, fatigues, dirt, vibrational exposure, susceptibility to lose fittings and also overloading.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on “Pattern Allowances”.

1. A pattern is generally made up of how many pieces?

a) 1

b) 2-3

c) 4-5

d) 6

Answer: b

Explanation: A pattern is basically a duplicate of the object that we intend to cast. Patterns can be made up of wood, plastics or metals. A pattern is generally made up of two or three pieces, whereas it is casting which is in one piece.

2. How does pattern vary in size with casting?

a) Pattern is larger in size

b) Casting is larger in size

c) Both have same size

d) Size depends on other factors

Answer: a

Explanation: Patterns are duplicates of the objects we desire to cast. These patterns can be made up of plastics, metals or wood. A pattern is slightly larger in size as compared to casting because a pattern carries various allowances and the core prints.

3. A pattern carries which allowance for internal and external surfaces?

a) Shrinkage allowance

b) Machining allowance

c) Distortion allowance

d) Draft allowance

Answer: d

Explanation: Draft allowance is also known by the name of tapering allowance, as the diameter of the cast goes on increasing in a trapezoidal shape from the bottom. A pattern has a draft allowance of an order of 1 and 3 degrees for external and internal surfaces respectively.

4. What is draft allowance also known as?

a) Shake allowance

b) Contraction allowance

c) Taper Allowance

d) Rapping Allowance

Answer: c

Explanation: None.

5. Machining allowance does not depend on which of the following factor?

a) Solidifying contraction

b) Machining method

c) Shape and size of casting

d) Casting method

Answer: a

Explanation: Machining allowance does not depend on solidifying contraction as it is one of the form of shrinkage allowance. But, machining allowance depends on remaining other factors.

6. How much does the distortion allowance vary?

a) 1mm to 10mm

b) 2mm to 20mm

c) 1mm to 15mm

d) 2mm to 15mm

Answer: b

Explanation: In distortion allowance, the amount goes on to vary from 2mm to 20mm. This allowance depends on the shape of the casting that is being used. It also depends on the size of the cast and the material that is being employed for the casting.

7. Shrinkage allowance does not depend on which of the following factor?

a) Moulding method

b) Casting dimension

c) Pouring temperature of molten metal

d) Amount of finish required

Answer: d

Explanation: Shrinkage allowance does not depend on the amount of finish required. The amount of finish needed on the machining portion is a factor on which Machining allowance depends. Shrinkage allowance depends on all other remaining factors.

8. Ferrous metals need more allowance than non-ferrous metals.

a) True

b) False

Answer: a

Explanation: Ferrous metals have dimensions on casting which have a larger size to provide stock than the dimensions of the casting of the non-ferrous metals.

9. A pattern is shaken by striking it with a wooden piece. A negative allowance is provided for this. Which allowance is it?

a) Machining Allowance

b) Rapping Allowance

c) Distortion Allowance

d) Contraction Allowance

Answer: b

Explanation: In rapping or shake allowance, the pattern is taken out of the mould and it is rapped or shaken, so as to free it from the adjoining sand. Due to this, there may be a little increase in the size of the mould cavity.

10. The following figure depicts which allowance?

a) Machining Allowance

b) Shrinkage Allowance

c) Draft Allowance

d) Shake Allowance

casting-questions-answers-pattern-allowances-q10

Answer: c

Explanation: The pattern is being taken out of the mould without the mould cavity getting damaged. The pattern is having a tapered shape, that is, it has a tapering allowance. Tapering allowance is also called a draft allowance. Hence, this figure depicts draft allowance.

This set of Casting, Forming and Welding Multiple Choice Questions & Answers  focuses on ” Heating And Pouring”.

1. For casting operation, a metal must be heated to what temperature?

a) Above solidifying temperature

b) Above vapourising temperature

c) Above melting temperature

d) Above room temperature

Answer: c

Explanation: For casting operations to take place, the metal to be casted must be heated above the melting temperature. The casting cannot be done at room temperature, as the metal needs to be liquefied first.

2. Which of the following is not a furnace used for heating?

a) Cupola furnace

b) Crucible furnace

c) Electric arc furnace

d) Blow air furnace

Answer: d

Explanation: Among the following, blow air furnace is not a type of furnace which is used for the heating purposes, whereas cupola, crucible and electric arc, are furnaces which are regularly used for heating.

3. Heat required to raise the temperature to the melting point is called what?

a) Sensible heat

b) Latent heat

c) Calorific heat

d) Specific heat

Answer: a

Explanation: Heat required to raise the temperature to the melting point is called as sensible heat. When there is a change of state of a material, keeping the temperature constant, that heat is called as latent heat.

4. The heat needed for a change of state of a material without changing the temperature is called what?

a) Sensible heat

b) Latent heat

c) Calorific heat

d) Specific heat

Answer: b

Explanation: The heat needed for a change of state of a material without changing the temperature is called as latent heat. Latent heat is also referred to as hidden heat.

5. If there is an increase in the mass of the metal being heated, how would it affect the total heat energy required to raise the temperature of metal?

a) Increases

b) Decreases

c) No affect

d) Quantities not related

Answer: a

Explanation: With an increase in the mass of the metal which is being heated, there would be an increase in the total heat energy which is required to raise the temperature of the metal.

6. What is the unit of specific heat of solid metal?

a) J/kg

b) J °C/kg

c) J/kg °C

d) °C/kg

Answer: c

Explanation: The units to measure the specific heat of a solid metal or that of liquid metal is given by J °C/kg, where Joule is unit of energy, Celcius is the unit of temperature and kg is the unit of mass.

7. When the molten metal is put into the mold, what is that temperature called?

a) Melting temperature

b) Vapourising temperature

c) Pouring temperature

d) Room temperature

Answer: c

Explanation: For a molten metal to be able to be poured, the temperature which it is required to possess is called as pouring temperature. This temperature is higher than the melting temperature but lower than the melting temperature.

8. In any flow through a system, if the area of cross section in which the metal is flowing, decreases, how will it affect the velocity?

a) Increases

b) Decreases

c) No affect

d) Quantities not related

Answer: a

Explanation: If the area of cross section of the system through which the molten metal is flowing, gets a decrease, then the velocity of the flow would increase, as the two hold an inverse relation.

9. What is the shape of the sprue?

a) Cuboidal

b) Cubicle

c) Trapezoidal

d) Spherical

Answer: c

Explanation: The sprue is essentially tapered, giving it a trapezoidal look. It needs to be tapered, because of the inverse relation between area and velocity.

10. According to Bernoulli’s theorem, energies at two points in a flowing liquid are equal.

a) True

b) False

Answer: a

Explanation: According to Bernoulli’s theorem, the energies at two points in a flowing liquid, in a system having equal or unequal cross section areas, at same or different heights, are equal.

This set of Casting Multiple Choice Questions & Answers focuses on “Hot Chamber And Cold Chamber Die Casting”.

1. In pressure die casting, what is the minimum pressure that can be applied?

a) 50 kg/cm 2

b) 60 kg/cm 2

c) 70 kg/cm 2

d) 80 kg/cm 2

Answer: c

Explanation: The minimum pressure, which can be applied in a pressure die casting is 70 kg/cm 2 . Below this pressure at 50 or 60kg/cm 2 , the process of casting will not take place.

2. What is the maximum pressure, which can be applied in a pressure die casting?

a) 4530 kg/cm 2

b) 4980 kg/cm 2

c) 5000 kg/cm 2

d) 5100 kg/cm 2

Answer: c

Explanation: The maximum pressure, which can be applied in a pressure die casting is 5000 kg/cm 2 . For some castings, with lesser hardness, the maximum pressure limit is lesser. If the magnitude of pressure applied exceeds the value of 5000kg/cm 2 , then the cast may get damaged.

3. Alloys of which of the following metal is not used for hot chamber die casting?

a) Tin

b) Lead

c) Zinc

d) Iron

Answer: d

Explanation: Among the following metals, the alloys which are made up of iron are least manufactured using hot chamber die cast method, while all others are widely used.

4. In cold chamber die casting, what is the minimum pressure that can be applied?

a) 140 kg/cm 2

b) 180 kg/cm 2

c) 150 kg/cm 2

d) 200 kg/cm 2

Answer: d

Explanation: In cold chamber die casting, a decent amount of pressure has to be given. The minimum pressure, which can be applied in a cold chamber die casting is 200 kg/cm 2 .

5. In cold chamber die casting, what is the maximum pressure that can be applied?

a) 500 kg/cm 2

b) 1000 kg/cm 2

c) 1500 kg/cm 2

d) 2000 kg/cm 2

Answer: d

Explanation: None.

6. In hot chamber die casting, before the end of the stroke, what uncovers the port?

a) Injector

b) Plunger

c) Burning flame

d) Die cavity

Answer: b

Explanation: In the process of hot chamber die casting, as soon as the stroke ends, there has to be some part which would remove the cover over the port. In hot chamber die casting, before the end of the stroke, it is the plunger that uncovers the port.

7. Which of the following is not counted among the limitations of pressure die casting?

a) Only small parts can be produced

b) High cost

c) Low scale production

d) Castings are porous

Answer: c

Explanation: Pressure die casting is used for mass production, the reason being, that equipment needed in pressure die casting is not available at low costs. The dies used in this process too are very expensive.

8. Up to what tolerances can pressure die casting be possible?

a) ± 0.067mm

b) ± 0.076mm

c) ± 0.025mm

d) ± 0.052mm

Answer: b

Explanation: Pressure die casting, overall is a very useful process. It is handy when small parts are to be produced. Up to ± 0.076mm of close tolerance, in pressure die casting, making small parts becomes possible.

9. Up to what thickness can the sections be casted?

a) 0.3mm

b) 0.4mm

c) 0.5mm

d) 0.6mm

Answer: c

Explanation: In pressure die casting, it is one of the advantages of this process, that castings which have very small sections too can be casted by it. The section of the casts can be manufactured up to 0.5mm.

10. In pressure die castings, production rate is low.

a) True

b) False

Answer: b

Explanation: In pressure die castings, a very high production rate is possible, as it becomes economical for large quantities.