Question

How much percentage of water or moisture is contained by green sand cores?

(a) 5%

(b) 10%

(c) 20%

(d) 40%

This question was posed to me during a job interview.

My doubt is from Dielectric Core Bakers in section Core and Core Making of Casting-Forming-Welding I

Answer 1

Correct answer is (a) 5%

The explanation: Green sand cores are made of green sand which mainly contains water or moisture nearly about 5% and 15 to 30 % of clay. It imparts very high permeability to the core material and hence reduces the chance of defects such as shrinkage or voids in the casted parts. Green sand cores are not dried but usually baked by dielectric bakers to maintain the moist content.