Volumetric shrinkage

Volumetric shrinkage is the contraction of polymer due to the change in temperature from melt temperature to ambient temperature.

High volumetric shrinkage can cause part warpage, sink marks, critical dimensions that are too small, and internal voids. Excessive wall thickness and inadequate packing can both contribute to high volumetric shrinkage in a part.

What to do

The key result to use to identify high volumetric shrinkage are the shrinkage results.

To reduce volumetric shrinkage, you can alter:

• Part design, such as the wall thickness.
• Mold design, such as gate positions.
• Processing conditions, by increasing packing pressure.