Manufacturing Engineering Questions & Answers – Pattern and Allowances

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This set of Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Pattern and Allowances”.

1. The allowance provided to take care of the contraction of casting is known as?
a) Draft allowance
b) Shrinkage allowance
c) Machining allowance
d) Shake allowance
View Answer

Answer: b
Explanation: Most metals contract or shrink volumetrically on cooling. The solid-state shrinkage refers to the reduction in volume caused metal loses temperature in solid state. To account for this, shrinkage allowance is provided on the patterns.
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2. Which one of the following statement is not true regarding Contraction?
a) Contraction of liquid takes place from the pouring temperature to the freezing temperature
b) Contraction is associated with the change of phase from liquid to solid
c) Contraction of solid is from the freezing temperature to the room temperature
d) Contraction is not associated with the change of phase from liquid to solid
View Answer

Answer: d
Explanation: As most metals contact during solidification, this contraction can happen at two stages. The liquid stage refers to the reduction in volume when the metal changes from liquid state to solid state at the solidus temperature. To account for this shrinkage; riser; which feed the liquid metal to the casting, are provided in the mold. To compensate the solid state shrinkage, shrinkage allowance is provided on the patterns.

3. While calculating the linear dimension of a material, shrinkage allowance is always?
a) Added
b) Subtracted
c) Multiplied
d) Divided
View Answer

Answer: a
Explanation: While calculating the linear dimension of a material shrinkage allowance is always added. The allowance provided to take care of the contraction of a casting is known as shrinkage allowance. During solidification of casting, volume decreases and hence contraction occurs.
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4. Which one of the following is a negative allowance?
a) Draft allowance
b) Shrinkage allowance
c) Shake allowance
d) Machining allowance
View Answer

Answer: c
Explanation: All metals shrink when cooling except perhaps bismuth. This is because of the inter-atomic vibrations which are amplified by an increase in temeprature. The shrinkage allowance is always to be added to the linear dimensions. Even in case of internal dimensions.

5. Which one of the following is not used to make patterns?
a) Wood
b) Plastics
c) Metals
d) Ceramics
View Answer

Answer: d
Explanation: There are different types of pattern materials: 1. wood pattern (teak wood, Mohagaoni, etc.), 2. metal pattern (aluminium, white metal, titanium), 3. Plastic pattern (epoxy resin, PVC, nylon, cellulose, polystyrene, etc.), 4. wax patterns (handicrafts).

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6. Which one of the following will not give good dimensional accuracy in the presence of moisture?
a) Wood
b) Plastics
c) Metals
d) Ceramics
View Answer

Answer: a
Explanation: Wood absorbs moisture as a result of which the dimension changes. To compensate such losses some allowance should be given.

7. The choice of pattern material depends upon:
i. On size of casting
ii. Number of casting to be made from pattern
iii. Dimensional accuracy
Which of the following is correct?
a) (i) and (ii)
b) (i) only
c) (i), (ii) and (iii)
d) (ii) and (iii)
View Answer

Answer: c
Explanation: All the statements are correct about pattern materials. The choice of pattern material depends upon on size of casting, number of casting to be made from the pattern, dimensional accuracy.
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8. In order to reduce the chances of damage due to withdrawing of a pattern from the mould is done by giving ________
a) Draft allowance
b) Shrinkage allowance
c) Distortion allowance
d) Shake allowance
View Answer

Answer: a
Explanation: While removing the pattern from the mould, the parallel surface to the direction at which pattern being withdrawn has a chance of getting damaged. The draws allowance will allow this easy removal of pattern from the old and does not affect the actual dimension of casting.

9. To have good surface finish and accuracy which of the allowance is given?
a) Draft allowance
b) Shrinkage allowance
c) Shake allowance
d) Machining allowance
View Answer

Answer: d
Explanation: The necessity of machining allowance is as follows: 1. for removing surface roughness, slag, dirt and other imperfections form the casting, 2. For obtaining exact dimensions on the casting, 3. To achieve desired surface finish on the casting.
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10. For good dimensional tolerances and smooth surface which of the following is used as pattern material?
a) Wood
b) Plastics
c) Metals
d) Ceramics
View Answer

Answer: c
Explanation: The primary benefits of using ceramic patterns are as follows: 1. It is a reusable pattern, 2. close dimensional accuracy, 3. excellent surface finish. There are two types of ceramic mold casting known as the “unicast process” and the “shaw process”.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter