The QSM (Pin) technology was one of the decisive co-developments made by TROESTER in the mid 70's. This technology, which has been continuously updated since then, allows tire manufacturers and other rubber-processing industrial sectors to process a diverse range of rubber compounds and still achieve optimum plastification without an extrusion screw changeover. The easy transference of this technology to all extruder sizes - in addition to the outstanding results in output and quality - was decisive in the rapid spread of this cold-feed extruder to all areas of the rubber industry. The QSM-Extruder is thus the complete, universal system for the entire range of rubber compounds.

A QSM (cross-flow mixing) Extruder is of a similar design to a conventional cold-feed extruder. The difference lies in the combination of screw and barrel which depending on the application, is equipped with up to 12 pin rows. The pins eliminate a problem which leads to a noticeable drop in throughput and extrudate quality in the operation of large, conventional cold-feed extruders. Due to temperature and viscosity differences, where no material exchange occurs between neighboring compound layers, "islands" form in the rotating flow between the screw flights. These layers insulate themselves from each other, thus preventing proper mixing of the extrudate.

The QSM pins which are inserted through the barrel from the outside (see diagram below), divide the flow off rubber, invert it and mix the layers with each other. This results in the formation of permanent new surfaces and leads to an intensive exchange of materials and heat (see photograph above).

The QSM-Extruder at a glance:

• universal for all rubber compounds;
• high throughput, whilst maintaining optimum product quality;
• 60 - 300 mm screw diameters can be supplied;
• self-cleaning, in common with conventional extruders;
• also available as vacuum-version.