Some plastic parts quickly swell or swell on the back of the metal insert or in a particularly thick part after the mold is demolded. This is because the plastic that is not completely cooled and hardened is caused by the expansion of the gas under the action of the internal pressure.
solution:

1. Effective cooling. Reduce the mold temperature, extend the mold opening time, and reduce the drying and processing temperature of the material.

2. Reduce the filling speed, reduce the forming cycle and reduce the flow resistance.

3. Increase holding pressure and time.

4. Improve the condition that the wall of the part is too thick or the thickness changes greatly.