Draft is the taper that allows a formed part to release from the tool. Insufficient draft increases sliding contact and can cause sticking, scuffing, distortion, extended cooling, or tearing during demolding.
The required angle is not fixed. Positive tools usually need more release allowance because the part shrinks onto them. Texture, draw depth, polymer shrinkage, tool temperature, undercuts, and surface finish all affect the requirement.
Evaluate the release condition
Scuff marks that follow the direction of tool withdrawal are a strong draft indicator. If release improves only when the part is unusually hot, the geometry may be locking as shrinkage develops. If the problem varies with mold temperature or cooling time, thermal control is also involved.
Draft should be increased where design permits. Polishing, controlled texture, air eject, split tooling, or a stripper may support release, but they do not eliminate a geometric lock. Release agents should not be used as the primary fix for production tooling with inadequate draft.