Question

Breaking of the sand mould is done after sufficient cooling of castings, to have_____

(a) proper surface finish of castings

(b) no any distortion to castings

(c) high casting yield

(d) less casting yield

This question was addressed to me in homework.

My question is from Casting Cleaning topic in section Pouring – Gating Design, Melting Furnaces, Melting and Casting Quality of Casting-Forming-Welding I

Answer 1

Correct answer is (b) no any distortion to castings

The best explanation: The sand mould is to be broken to extract the casting. But the breaking of the sand mould is to be done only when the castings are sufficiently cooled, since the metal at high temperature has very little strength, due to this it may cause distortion to the casting if breaking of mould is done before proper cooling of the mould.