Question

Sprue design is made tapered instead of straight ___________

(a) To easy flow of molten metal

(b) To have smoothness in the metal flow

(c) To maintain the pressure balance

(d) To avoid the erosion of mould sand

The question was posed to me in an internship interview.

My enquiry is from Aspiration Effect topic in division Pouring – Gating Design, Melting Furnaces, Melting and Casting Quality of Casting-Forming-Welding I

Answer 1

The correct option is (c) To maintain the pressure balance

The explanation: Pressure balance is maintained, to avoid the negative pressure (to ensure positive pressure anywhere in the liquid column), the sprue should be tapered. The ideal shape of the sprue is parabola but to reduce the manufacturing difficulty shape of the sprue is considered as tapered cylinder.