Question

Which of the following reasons stand for the crumbling of green sand mould?

(a) The sand grains are not adequately bonded

(b) Excess of water and clay mixture

(c) Due to the presence of impurities in the green sand mould

(d) Fine grain size

I have been asked this question in class test.

I need to ask this question from Green Sand Mould in division Pattern and Mould, Principles of Gating & Risering of Casting-Forming-Welding I

Answer 1

The correct choice is (a) The sand grains are not adequately bonded

To explain: Sand mould crumbles because moulding sand is not adequately compacted in the flask. Clay, together with water acts as a bonding agent and the organic additives also save the mould from crumbling by burning out at high temperatures and make room for the moulding sand to expand.