machinery feature | wood-plastic composites
‘woodstock’ technology uses co-rotating twin-screw extruders and the resulting sheets are mainly used
for automotive internal trims, as well as in footwear and construction applications. one line that was delivered last year to a leading
European processor of such materials is designed to make 1,700 mm wide sheets by direct extrusion
achieved because of the
reduced raw material consump- tion. Additional benefits of foaming
B&P and Milacron combined their compounding and extrusion expertise to create the TE 125
include the increased thermal and acoustic insulation values of the finished profiles. The cincinnati milacron presentation also covered the use of co-extrusion to incorporate increased levels of recycled material behind thin cap-stock layers that provide good surface finish and weathering resistance. Jones outlined a Tc86 line for wpc co-extrusion using Maguire loss-in-weight feeders to blend multiple additives and complete formulations above the extruder. He said that the system provides high outputs using dried wood flour or agglomerated pellets. cincinnati milacron has also been working with
compounding machinery specialist B&P Process Equipment. They have been collaborating to produce complete lines for the high-output production of wpc deck-board. B&p provides its Bp series co-rotating twin-screw
extruders with its patented XlT discharge and VVSS vacuum vent side stuffers. The unit is integrated with milacron’s mosaic control panel to complete milacron’s TimberEx TE production package for wpc deck-board. The patented XlT discharge technology eliminates
the need for a gear pump or a single-screw extruder for pressure generation. Based on a cooled barrel segment without moving parts, it generates pressure at the die without creating a temperature spike. in addition, the high free volume of the twin-extruder helps it handle heat-sensitive materials. B&p has a TE 125 mm machine in stock, ready for
This Gneuss DA pressure
transducer has a special GX- coating to withstand abrasive
materials such as WPCs
40
shipping to produce deck-board. in addition, its demonstration centre in Saginaw, michigan, uSA, is equipped with a 50 mm compounder to perform deck- board production trials and demonstrations. The company adds that its Bp twin-screw extruders
with XlT and VVSS can also be used for the production of wpc pellets with moisture levels below 1% and an extra-long shelf life. ICMA San Giorgio has developed machinery for the direct extrusion of sheets from wpc materials. its
compounding world | February 2012
www.compoundingworld.com
of polyolefins compounded with wood flour. The hourly output of the line is 1,500 kg. it is based on an mcm /140 co-rotating twin-screw extruder with an l/d ratio of 40. This is equipped with two side-feeding units. one of the challenges has been to make thick sheets
– of up to 12 mm – using standard calendering technol- ogy. This is a new demand from the construction market, says the company. Because of this, the calender has been designed with a specific feature: the flexibility of changing the roll axis position to achieve the optimal calendering point for each thickness. This gives advantages in the optimisation of plastic coating on the textile substrate.
Abrasion resistance The abrasive nature of wpcs means that extruders require hard-wearing screws and barrels for long-term use. For example, Cincinnati Milacron is using hard- wearing tungsten coatings on barrels and screws to give uniform resistance. KraussMaffei Berstorff has also been developing its
extruders to increase their wear resistance when handling natural fibres in polyolefins or pVc. its counter-rotating twin-screw extruders are now offered with tungsten-carbide armouring and hard chrome plating of the screws, plus bimetallic plating of the barrel bores. in addition, the screw geometry has been adapted to give optimised clearances to reduce the risk of adhesive wear. it is also important that instrument sensors are able to stand up to the aggressive environment. with this in
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