Krauss Maffei, represented in Oceania by HBM Packaging & Plastics Technologies , have worked with the Hanover University of Applied Sciences, to develop a twin-screw extruder that eliminates the problems that have been inherent in the processing of natural fibres with plastics.
Natural fibre reinforcements are an inexpensive, lightweight and ecologically friendly alternative to conventional reinforcing materials or fillers. However, the materials require pre-drying that is expensive and time consuming.
The patented Multi-Process-Elements (MPE) technology ensures gentle and cost effective incorporation of the natural fibres. It allows the line to be tailored to the moisture content of the material that is to be processed, whether it be flour, wood fibres, flax, hemp, rice husks or palm fibres. An additional advantage is that by eliminating the need for pre-drying, the risk of explosion is eliminated.
The process involves the polymer introduction into the feed zone by gravimetric dosing equipment and melted in the plasticising zone. In addition to the polymer, various additives are fed into the feed section to improve the material properties. The natural fibres are supplied through downstream side feeders and incorporated into the melt by means of the MPEs. Openings arranged along the processing section remove moisture released from the natural fibres. After these have been mixed in, the melt is degassed under vacuum to further remove moisture and volatiles. During a final step, the melt pressure is increased prior to processing through the die.