Question

There is no requirement of any risers for the casting of grey cast iron.

(a) True

(b) False

I got this question in an internship interview.

Origin of the question is Riser Design topic in section Pattern and Mould, Principles of Gating & Risering of Casting-Forming-Welding I

Answer 1

Right answer is (a) True

The explanation is: In grey cast iron, while solidification the process of graphitization occurs, this increases the volume of the casting and counteracts the metal shrinkage, so risers can be eliminated for the casting of grey cast iron. But for some metals like aluminium and steel, the volumetric contraction is very high, so elaborate risering is required.