Blow holes in castings are due to
A.high moisture content of the sand
B.low permeability of sand
C.excessive fine grains and gas producing ingredients
D.any of the above
Category: Foundry Technology Mcqs
The contraction allowance for pattern depends on
A.composition of the metal
B.method of moulding used
C.pouring temperature
D.all of the above
There is no need for the withdrawal of pattern from the mould in case of
A.wax patterns
B.hollow patterns
C.patterus with core
D.consumable patterns
Which of the following is very powerful carbide former in cast iron?
A.Silicon
B.Vanadium
C.Chromium
D.Nickel
Which of the following holes appear on the surface of the casting when it is machined?
A.Blow holes
B.Pin holes
C.Gas holes
D.Slag holes
In case of carbondioxide moulding, the binder used is generally
A.sodium silicate
B.china clay
C.coal dust
D.graphite
Which of the following statement about gates is incorrect?
A.he size of gate depends upon the rate of solidification
B.A small gate is used for castings which solidify rapidly
C.More than one gate may be used to feed a fast freezing casting
D.A gate should not have sharp edges
The residual stresses in casting occur due to
A.sand particles being taken into molten metal while pouring
B.the insufficient gate size
C.the differential solidification rate of thin and thick sections of casting
D.none of the above
Pattern draft for internal surfaces is
A.Less than that for external surfaces
B.More than that for external surfaces
C.Equal to that for external surfaces
Sand acquires a predetermined shape under pressure and retains the same when pressure is removed. This is due to the property of sand known as
A.Cohesiveness
B.Plasticity
C.Refractoriness
D.none of the above
