Question

What should be the ratio of rib thickness to wall thickness in castings for proper avoiding of concentration of metal at joints?

(a) 1 to 2

(b) >2

(c) >1

(d) 0.6 to 0.8

I have been asked this question in final exam.

Query is from Product Design for Sand Castings topic in chapter Pouring – Gating Design, Melting Furnaces, Melting and Casting Quality of Casting-Forming-Welding I

Answer 1

The correct option is (d) 0.6 to 0.8

To elaborate: Rib thickness/Wall thickness = 0.6 to 0.8, When the concentration is reduced, one of the walls is made thinner as shown in below figure. That is why for castings, ribs are always made thinner than the wall in the ratio, to avoid the concentration of metal at joints.