From the perspective of motion principle, the co-rotating intermeshing and counter-rotating intermeshing and non-intermeshing types in twin-screw extruders are different.

1. Co-rotating intermeshing twin-screw extruder

There are two types of extruders of this type, low-speed and high-speed, with the former mainly used for profile extrusion and the latter for specialty polymer processing operations.

Close meshing extruder. Low-speed extruders have a closely intermeshing screw geometry in which the flight profile of one screw closely mates with the flight profile of the other screw, a conjugate screw profile.

Self-cleaning extruder. High-speed co-rotating extruders have closely matched flight profiles. This kind of screw can be designed to have a relatively small screw gap, so that the screw has a closed self-cleaning effect. This twin-screw extruder is called a compact self-cleaning co-rotating twin-screw extruder.

2. Counter-rotating intermeshing twin-screw extruder

The gap between the two screw grooves of the closely meshing counter-rotating twin-screw extruder is very small (much smaller than that in the co-rotating twin-screw extruder), so it can achieve positive conveying characteristics.

3. Non-intermeshing twin-screw extruder

The center distance between the two screws of the non-intermeshing twin-screw extruder is greater than the sum of the radii of the two screws.