Question

Which of the following effects can produce porous castings?

(a) Aspiration effect

(b) Viscous effect

(c) Shapiro effect

(d) Turbulent effect

I have been asked this question during an internship interview.

I want to ask this question from Aspiration Effect topic in chapter Pouring – Gating Design, Melting Furnaces, Melting and Casting Quality of Casting-Forming-Welding I

Answer 1

Right answer is (a) Aspiration effect

Easy explanation: When the mould is made, care should be taken to ensure that the pressure anywhere in the liquid metal stream does not fall below the atmospheric pressure. Otherwise, the gases originating from baking of the organic compounds in the mould will enter the molten metal stream, producing porous castings. This is known as Aspiration effect.