UNDERCUTS

Definition:

Undercuts are indentation or projection on the walls of a plastic part which interfere with simple ejection from a two part mold; hence they must be avoided wherever possible.

·         Undercuts unduly complicates the mold design and increases the cost considerably because special split molds are required, retracting mechanisms may be required etc.

·         Internal undercuts require more expensive tooling than the parts with external undercuts.

·          Post mold machined undercuts are often cheaper than those molded in, especially external undercuts and circular undercuts.