Question

In sand moulding, the thickness of sand mould and bond strength should be high as much as possible to avoid sand inclusion in machine parts.

(a) True

(b) False

The question was asked in an interview.

My doubt stems from Mechanization topic in portion Foundry Mechanizations of Casting-Forming-Welding I

Answer 1

Right choice is (b) False

The explanation is: High bonding strength of sand in mould mixture and its thickness does not avoid the problem of sand inclusion in machine parts greatly, and even this reduces permeability of moulding mixture in a great amount which results into the formation of castings with defects like blow holes.