What Causes Sink Marks in Injection Molded Parts? (October 2026)
Sink marks in injection molded parts are shallow surface depressions caused by a volumetric shrinkage mismatch: the outer skin of a plastic part solidifies and shrinks while the thicker material behind it is still cooling and contracting, and the frozen surface collapses inward to absorb the difference. They show up on the face opposite a … Read more