For steel castings, the following type
of sand is better ________ .
fine grain
coarsegrain
medium grain
fine grain, coarsegrain and medium grain,
all are equally good
coarsegrain
For steel casting, coarse grain type
of sand is better.
For uniform casting, we need the heat
transfer from the casting should be low and uniform.
Case 1 : If we use fine grains then heat transfer rate will be high.
Case 2 : If we use coarse grains then air resistance between voids of coarse grains sand plays an important role to reduce the heat transfer from the casting to get uniform solidity.
Hence, the correct option is (B).
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