COMPOUNDING: New Screw Elements Permit Major Output Gains

Involute screw and kneading elements significantly increase throughputs of twin-screw compounding extruders.

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Involute screw and kneading elements with a new and patented cross-section design have been introduced by Coperion Corporation (U.S. office in Sewell, N.J.) to significantly increase throughput rates of its twin-screw ZSK compounding extruders. These screw elements are suited to highly filled recipes, such as 70-85% CaCO3 or TiO2, and 20-50% talc, in PP or PE. Besides higher throughput rates, these involute screw elements ensure higher loading of filler, better dispersion and homogenization, and lower energy consumption.

Coperion’s tests reportedly showed “remarkable” throughput increases. For example, when processing PP with 70% CaCO3 on a ZSK 58 Mc18, the new screw elements achieved a 64% increase from 1212 to 1984 lb/hr. When processing PE with 80% CaCO3 on a ZSK 92 Mc18, throughput increased 36% from 4850 to 6614 lb/hr.