The process of rolling and The process of working metal to a desired shape by impact or pressure in hammers, forging machines (upsetters), presses, rolls, and related forming equipment. a hollow Raw material or forging stock (also called a "slug" or "multiple") from which a forging is made. over a A blunt-ended tool or rod used to retain or enlarge the cavity in a hollow metal product during forging. in order to produce a weldless, seamless ring or tube. See Saddle/Mandrel Forging.