This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Pattern Allowances”.
1. A pattern is generally made up of how many pieces?
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
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
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
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
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
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
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.
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
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.
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.
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