Friday, April 23, 2010

reinforced plastics


 
Hanover, April 22, 2010 – Intensive material and heat exchange, narrow residence time distribution, efficient degassing and speed-independent output rates – these are the highlights of the ZE-UTX twin-screw extruder series offered by Hannover-based KraussMaffei Berstorff, Hanover for optimum processing of natural fibre reinforced compounds.

 

Thanks to the continuous development and improvement of technical details and its wealth of experience, the extruder manufacturer has succeeded in designing the perfect extruder for high-performance compounding at low operating costs. Large free volume, special mixing elements and efficient barrel temperature control are the key factors that ensure excellent processing results.

 

The R version of the ZE-UTX series with an OD/ID ratio of 1.74 is perfectly suited for the processing of undried natural fibbers. The deep screw channels guarantee a large free volume and thus reliable discharge of the water vapour released during processing. Combined with special 6D long barrel elements, this ensures highly efficient degassing. Tests have confirmed that natural fibbers with a residual moisture content of up to 12% can be processed without any problems. The processing of undried natural fibbers offers two decisive advantages: on the one hand, operating costs are reduced as energy-intensive pre-drying is not required. On the other hand, material handling is facilitated and the risk of dust explosion is eliminated.

 

Gentle processing of natural fibres thanks to top technology

The patented KraussMaffei Berstorff Multi-Process elements used for this purpose ensure particularly gentle incorporation of natural fibbers. In contrast to conventional kneading block systems, high shear rates and temperature peaks that may lead to thermal damage of the natural fibbers are avoided. Nonetheless, these special mixing elements produce the desired homogenizing and dispersing effect and thus ensure comparable mechanical properties of the final product.

 

Finally, low barrel wall temperatures are of decisive importance for natural fibre compounding in order to avoid local melt overheating. This is why KraussMaffei Berstorff has developed a heat treatment method for the barrel elements based on an inductor that heats the figure-eight shaped barrel bore over a defined penetration depth via induced eddy currents. The barrel bore is subsequently cooled. Thanks to this process, the previously used wear protection liners are no longer necessary and the distance between the cooling bores and the processing chamber is reduced, which ensures highly efficient cooling capacity transfer.

 

In order to further increase cost-effectiveness and to achieve more gentle material processing, the natural fibre compound can be directly converted into the final product, e. g. film, profiles or sheet, by connecting the extrusion tool and the downstream equipment directly to the twin-screw extruder. KraussMaffei Berstorff offers a gear pump for this configuration that ensures surge-free melt flow at constant pressure at the discharge end of the extruder.

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