Publisher Summary Extrusion is a relatively new method of fabricating metals. Originally it was developed for the fabrication of lead piping for Victorian gas and water systems. It is possible to successfully extrude aluminium, copper, lead, and steel and their alloys. However, a special technique is required for steel. A typical press for the extrusion of copper alloys would be of about 5000-tonne ram-load capacity, and would consist of a heavy steel shell, lined with heat-resisting alloy steel. This could accommodate a billet of 560 mm diameter and 1 m length. The extrusion die is made of heat-resisting tool steel and the shape of the orifice together with the orifice bearing or parallel are carefully prepared by the die-room toolmaker. Extrusion dies are made of high-speed tool steel and are very important components in the extrusion process. As the die material is so expensive, it is often made in the form of a thin disc much smaller in diameter than the billet and is supported by a die bolster. The die orifice controls the shape of the extruded metal.