THE HOT EXTRUSION OF NON-FERROUS METALS

AbstractThe extrusion process, in which a metal or alloy billet is placed in a sealed container and then forced by pressure through a shaped opening or die, dates from the invention by Joseph Bramah in 1797 of a process of making lead pipes, although the first recorded manufacture of extruded l∼ad was carried out by Thomas Barr in 1820.1 Throughout the nineteenth century extrusion was confined to lead, and in the simple equipment employed for this purpose the container was also the mould, into which the lead was poured and allowed to solidify. Generally, the practice was to raise the container by means of a hydraulic or screw mechanism against the die held in a rigid hollow support through which the lead pipe emerged.