Gneuss Kunststofftechnik GmbH has introduced its latest development—a patented evacuation technology for polymer melts. This system represents a significant step with regard to vacuum degassing. The special Multi Rotation System (MRS) allows an increase of the surface in contact with the polymer melt by a factor of approximately 25 compared with conventional twin screw processes. The polymer melt is delivered into a large single screw drum. The drum contains 8 or 10 (depending on the model size) small extruder barrels, parallel to the main screw axis. Installed in these small extruder barrels are the “satellite” screws, which are driven by a ring gear in the main barrel. The satellite screws rotate in the opposite direction to the main screw while they are being rotated around the screw axis.
This increases the surface exchange of the polymer melt, which is of significant importance when applying a vacuum. The extruder barrels, which are cut into the drum of the multi rotation system, are approximately 30% open to ensure the optimum melt transfer into the barrels and so that the evacuation can take place without restrictions. Further, precise control of the melt temperature is possible as the temperatures of all the surfaces in contact with the melt can be controlled accurately.