Extruders (from the Latin: extrudere = to push out) are machines for manufacturing tubes, hoses, profiles etc. from thermoplastics.

The powdery or granulated thermoplastic is fed to the machine via the hopper (1). In the area of the screw (2) it is heated or cooled, homogenized, plasticated, conveyed and finally extruded through the shaping nozzle in the head (3). As a rule the point of entry of the screw(s) into the housing is sealed by lip seal rings. The rotary transmission for the heat transfer oil used in the tempering is sealed by mechanical seals.