Technical presentation of corotative extruders

The barrel of a corotating twin-screw extruder, comprising two smooth cylindrical bores intersecting in a figure-of-eight shape, acts as an enclosure for the pressurized material. It can be heated from the outside by resistors and cooled by fluid circulation holes, and transmits its temperature to the extruded product. Inside the sheath, two screws of identical geometry rotate in the same direction, meshing with each other and having the same outside diameter as the sheath bores, but with the same clearance.

Screws can be single- or multi-threaded. Their cross-section in a plane perpendicular to the axes results directly from the number of threads (see figure