Engineering Questions with Answers - Multiple Choice Questions

# Manufacturing Engineering – Pattern and Allowances

1 - Question

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
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.

2 - Question

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
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 - Question

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

4 - Question

Which one of the following is a negative allowance?
a) Draft allowance
b) Shrinkage allowance
c) Shake allowance
d) Machining allowance
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 - Question

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

6 - Question

Which one of the following will not give good dimensional accuracy in the presence of moisture?
a) Wood
b) Plastics
c) Metals
d) Ceramics
Explanation: Wood absorbs moisture as a result of which the dimension changes. To compensate such losses some allowance should be given.

7 - Question

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)
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.

8 - Question

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
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 - Question

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
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.

10 - Question

For good dimensional tolerances and smooth surface which of the following is used as pattern material?
a) Wood
b) Plastics
c) Metals
d) Ceramics