ME-542 Manufacturing with Non-metallic Materials

The Compression Molding Process

1. Material Preparation:
The molding compound or a prepreg is made, which involves compounding a resin
combining a resin with fibers, etc.

2. Pre-fill Heating
Heating speeds up the process. This may be done outside the mold to using dielectric
heating. With SMC heating takes place after the compound is placed in the mold.

3. Mold Filling
Mold filling starts when the polymer begins to flow and ends when the mold is full.
The flow controls the orientation of the reinforcing fibers. There is no mold
filling in laminates since there is no appreciable flow.

4. In-mold Curing
The part cures in the mold. Cure converts the polymer from a liquid into a solid.
There is an interaction between heat transfer and curing.

5. Part Removal and Cool-Down
Residual stresses are present, due to the difference in thermal expansion between
different positions in the part. As the part cools down, distortions appear. The
temperature distribution and the rate of cooling determine the level of residual stresses
present in the finished part