Wood-plastic composites | machinery feature
mind, the Measurement Technology division of Gneuss has developed a new hard membrane coating option for its sensors which it says is “especially suitable for very abrasive media such as WPCs”. The new GX-Coating will be launched at the NPE exhibition in the USA in April.
Seeking the perfect mix Manfred Wiedmann, sales manager at Coperion, gave a presentation at AMI’s Wood Plastics Composites 2011 conference on optimising compounding lines for PVC- based WPCs. He explained that such formulations typically contain up to 50% wood along with PVC and a mixture of additives – stabilizer, lubricants and pigments or masterbatch – that frequently come in the form of a one-pack. The moisture content of the wood fibre or wood flour
can be up to 20%, which impacts on the handling, mixing, extrusion and pelletizing of the material, as well as product quality and energy consumption. Wiedmann said that for efficient processing, the moisture content of the wood should be below 1% to increase capacity, improve quality and reduce energy consumption. He explained that PVC-based WPCs need to be
produced in a two-stage process ideally with separate heating mixers for wood and PVC prior to being fed into the compounder/extruder. Coperion’s Kombiplast two-stage compounding
system can be used for compounding and pelletizing WPCs. Wiedmann outlined a system using a ZSK MegaVolume Plus twin-screw with a high Do/Di ratio of 1.80 and a high torque of 11.3 Md/a3
. This feeds into an
ES-A single discharge screw to give sufficient pressure for the EGR eccentric pelletizer. The two-stage Kombi- plast ensures that the compounding step is carried out without the axial back pressure of a compression zone or a die-plate. Steer Engineering has been highlighting the
capabilities of its Generation Next Omega H Class twin- screw extruder for the compounding of difficult-to- process materials, including wood and natural fibre composites. It has a very high specific torque rating of 17 Nm/cm3 at 720 rpm and can be supplied with a large external: internal screw diameter ratio (Do/Di) of 1.71. “Due to unsurpassed torque, increased free volume and decreased residence time, the H Class is capable of producing 25 to 50% more throughput than conventional extruders,” claims Steer’s founder and managing director, Dr Babu Padmanabhan. The H Class features three compact side feeders and a vacuum side stuffer for process flexibility.
Coperion’s two-stage Kombiplast combines a twin-screw
compounder with a single-
screw extruder and a pelletizer
Maag Group is the innovative solution provider for pump, pelletizing and filtration systems. We deliver high-quality components and complete systems, from extruder tips to pelletizers. In addition to our primary locations in Switzerland and Germany, we have eight sales and service offices around the globe to provide our customers with full service par excellence.
1 - 5 April 2012 West hall stand 5563
brands of maag group
Automatik Plastics Machinery GmbH Ostring 19 ß 63762 Grossostheim ß Germany ß T +49 6026 503 0 ß
info@maag.com
Maag Pump Systems AG Aspstrasse 12 ß 8154 Oberglatt ß Switzerland ß T +41 44 278 82 00 ß
welcome@maag.com
www.maag.com
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