Page 451 - Injection Molding Advanced Troubleshooting Guide

45 Voids

„ „45.1„ Description

Voids are internal pockets inside the part wall stock. Voids are different from bub-
bles even though they may appear the same. Bubbles are trapped gas in the part
but a void is actually a vacuum that was created from shrinkage. To distinguish a
bubble from a void slowly warm the wall stock with a heat gun. If the area sinks it
was a void, but if it blisters up it was a gas bubble. Figure 45.1 shows a void in a
polycarbonate part.
Also known as: internal sinks
Mistaken identities: gas trap, bubble, blister

Figure 45.1 Void in thick section of part