Question

Uncontrolled permeability in the green sand mould leads to ___________

(a) Blow Holes

(b) Chills

(c) Shrinkage

(d) Tearing

The question was posed to me in class test.

I need to ask this question from Types of Sand Moulds in chapter Pattern Materials & Moulding Sand Tests of Foundry and Forging

Answer 1

Right option is (a) Blow Holes

Explanation: The rate of flow of air passing through a standard specimen under a standard pressure is termed as a permeability number. The permeability of these holes should be properly controlled, otherwise blow holes and gas inclusions are likely to form.