Shrinkage and warpage can be seen if plastic material is processed and cooled down in the mold and later after ejection.
In order to compensate shrinkage the mold design is modified using a factor, which is very often based on experience.
The given dimension of the part is multiplied by the factor to enlarge the part and create a cavity based on the new dimensions.
A filling simulation can be done to predict warpage due to fiber orientation, stresses, etc. as well as the shrinkage of a part during production.
In order to compensate warpage the cavity is modified in the oposite direction of what can be seen as part warpage.
This modification is called tool adaptation.
To do this in a best way the simulation result warpage is multiplied with a factor of -1 and exported as .stl file for example.
In the CAD system the mold cavity is adjusted taking care of that no undercuts are build in.
It is essential that, based on the new cavity geometry a new simulation is done in order to verify the desired results.
If this simulation shows good results the tool adaptation can be implemented into the mold.

Tool Adaption in Plastic Industry

Simulations: Left: part warpage; right: tool adaption.

Related topics:
Reverse Engineering

This glossary of plastic industry is provided by PLEXPERT Canada Inc.