Question

Which of the following is used to remove the metal defect of cold shuts from the casting?

(a) Ejector pins

(b) Overflows

(c) Metal cores

(d) Biscuit/Sprue

This question was posed to me by my college professor while I was bunking the class.

I'd like to ask this question from Vacuum Die Casting in division Special Casting Techniques of Casting-Forming-Welding I

Answer 1

The correct answer is:

(b) Overflows

Explanation:

In casting, cold shuts are defects that occur when two streams of molten metal fail to fuse properly, resulting in weak or incomplete areas in the final casting. Overflows are used in the mold design to help ensure that the molten metal fills the mold properly. They act as additional channels for excess metal to flow out of the mold, which helps prevent the occurrence of cold shuts by promoting better filling of the cavity.

Let’s briefly look at the other options:

• Ejector pins (option a) are used to remove the casting from the mold after solidification, not to address casting defects like cold shuts.
• Metal cores (option c) are used to create hollow parts of a casting but do not specifically address cold shut defects.
• Biscuit/Sprue (option d) are parts of the gating system that guide the molten metal into the mold, but they do not correct cold shuts directly.

Thus, overflows are specifically designed to remove defects like cold shuts by ensuring proper flow and solidification of molten metal.