How Extrusion machines work? Extrusion machines force or pull unformed material into alignment guides and shaped dies to produce lengths of stock forms and cross-sectional shapes. Extrusion machines are used mainly in the plastics, metals, and composite-forming industries. Extrusion machines are also used in automotive, aerospace, and construction applications. The basic parts of an extruder include a tubular barrel, a revolving screw, and a ram or plunger within the barrel. An extruder also has a hopper at one end from which the material to be extruded is fed to the screw, ram, or plunger. A die at the opposite end is used for shaping the extruded mass. Extrusion machinery that can cut extruded materials into short or long intervals is also available.