Krauss Maffei have installed many WPC direct extrusion lines in the past 12 months including an installation for Oceplast, a leading French manufacturer of various WPC decking profiles. Their line consisted of a KMD 75-32/WPC twin-screw extruder, a calibration table, haul-off/saw combination and a tilting table that were designed specifically for the customer's requirements. The extremely compact line has been designed for the processing of extra wide profiles and has a maximum output of 200kg/hr.
The Krauss Maffei solution was chosen as the twin screw extruders have a high wear resistance rate required for the very abrasive properties of WPC compounds. The screws have tungsten carbide armour plating while barrels are lined with a bi-metallic bushing.
Direct extrusion allows products to be made in a single-step process by direct metering of the two compounds ie. wood and PVC. A two component gravimetric system transports wood flour and PVC dryblend into a dynamic mixer which feeds the perfectly homogenized material mixture directly into the extruder. The typical complex compounding process using a heat-cooling mixer is therefore not required, which saves production space and energy as the wood flour is already pre-dried.
Another recent installation was for Pinuform, a German company - which installed three WPC twin screw extruders and a twin screw compounding extrder to carry out direct extrusion. The company recycles wood chips from their timber mill and then uses these to produce WPC decking profiles.
Krauss Maffei is represented in Oceania by HBM Plastics Technologies.