Chapter 15, Problem 1RQ

What are some of the major disadvantages of the expendable-mold casting processes?

To determine

The major disadvantages of the expendable mold casting process.

Explanation of Solution

The expendable mold casting process includes sand, plastic, shell, plaster, and investment (lost-wax technique) moldings. Expendable mold castings processes have are temporary and non-usable molds.

Major disadvantages of expendable mold casting processes are written below:

1. High melting points materials are difficult to cast by using this process.
2. A new mold has to be made for each pour. Due to which there can be variation in dimensional accuracy, strength, moisture content, and pattern removal. Also, theproduction rate can be slow.
3. It requires highly skilled labor since the casting process is too complex.
4. Grey cast iron gives a negative allowance, which can break the pattern during the expendable-mold casting process.