RingExtruder RE®

Revolutionary and disruptive technology for continuous processing applications requiring low energy (i.e. low temperature) mixing and efficient degassing of melts.

Process Technology

What is a RingExtruder? How does it work?


Food-grade PET Recycling Compounding

Technical Data

Available machine sizes


Developed by Josef A. Blach in 1998, the RingExtruder RE® is a multi-screw extruder with twelve (12) co-rotating screws arranged symmetrically around a stationary core; each shaft rotates in the same direction on a fixed axis.

The outer barrel and the stationary inner core enclose the screws with the same gaps as found in twin-screw extruders. Transport of material takes place in a double helix around the stationary core and around each screw (click on the image to visualize material flow in the RingExtruder RE).

The intermesh area between the screws, also known as the apex, is used extensively in the RingExtruder RE as the central part of the process technology. In the intermeshing section, material is passed to the adjacent screw with a change in flow direction, resulting in elongational flow.

With twelve apexes, dispersion via elongation results in low energy input without the shear and pressure peaks associated with twin-screw extruders.

As a result of this patented geometry, the RingExtruder RE provides a high surface-to-volume ratio which is unmatched by any other multi-screw extruder while also maintaining self-wiping geometry. This feature provides enhanced thermal heat transfer for processing temperature-sensitive materials.

The combination of more frequent passages through the intermeshing sections and high surface-to-volume ratio provides superior degassing capability, one of the many benefits of the RingExtruder RE.

The arrangement of the screw shafts in an annular ring eliminates the spreading forces that are common in twin-screw extruders and therefore significantly reduces barrel and screw wear.

Play Video

Click on above image to see material flow with the RingExtruder RE

Modular Process Section for Flexible Process Requirements

Modular barrel design provides flexibility to configure any sequence of unit operations, up to 100D.

Top opening feed and vent barrels can be installed at any axial position

Liquid injection at any axial position (multiple injection ports can be arranged on top and sides at same L/D)

Combi-barrels for feeding/degassing on top and/or sides using side feeders or vent stuffers

Discrete temperature control for each barrel segment available in 4D or 6D lengths

Modular Screw Configuration

RingExtruder RE screw profiles are based on Erdmenger self-wiping designs


Solids feeding of raw materials into the RingExtruder RE

Venting & Degassing

Venting to atmosphere or under vacuum

Distributive Mixing

The 12 melt channels within the RingExtruder RE are repeatedly passed through the 12 intermesh zones (‘apexes’) where the flow is primarily elongational

Product Development

CPM Extrusion Group has laboratory capabilities at all its locations.