Also known as sub-bolster, dieThe machined recess in a die that gives the forging its shape. assembly, trimThe removal of the excess metal or flash produced during the forging process. The operation takes place in tools produced to the peripheral shape of the component, the component being pushed through the female impression by the identically-shaped male punch. The operation may be carried out hot or at room temperature.... More and pierceIn ring rolling, the process of providing a through hole in the center of an upset forging using a tapered or cylindrical punch. See Drifting. assembly. An assembly of top and bottom diesThe metal blocks into which forging impressions are machined and from which forgings are produced. and/or tools of each forming stationA regular stopping place in the die during the forging sequence. assembled into one unit.