Fold

A forgingThe process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. defect caused by folding the metal back on its own surface during its flow in the dieThe machined recess in a die that gives the forging its shape. cavityThe machined recess in a die that gives the forging its shape.. See LapA surface irregularity appearing as a fissure or opening, caused by the folding over of hot metal, fins or sharp corners and by subsequent rolling or forging (but not welding) of these into the surface..