Question

Which of the following casting process uses an expendable pattern?

• A. CO$_2$ casting
• B. Die casting
• C. Centrifugal casting
• D. Investment casting

Hint:

Investment casting uses wax patterns that are melted away—hence called an expendable pattern method.

Answer 1

The Correct Option is D

Investment casting, also known as lost-wax casting, is a process that uses an expendable wax pattern.
The wax pattern is created and then coated with a ceramic material to form a mold.
Once the ceramic hardens, the wax is melted and drained away, leaving a cavity into which molten metal is poured.
After casting, the ceramic shell is broken away to retrieve the final product, and the pattern is not reused.
Thus, the pattern in investment casting is expendable.
In contrast, CO$_2$ casting, die casting, and centrifugal casting use reusable or permanent patterns or molds.