Description:
<jats:title>Abstract</jats:title><jats:p>The addition of wood to polymers results in wood‐polymer composites (WPC), whereby the wood content can be up to 80 %. This composite is mainly processed in extruded deckings. The extrusion die is an essential part of the process, which determines both process parameters and the final product. A characteristic of WPC extrusion dies is a partial solidification of the melt before leaving the die. This solidification is necessary to ensure a dimensionally stable extrusion. For the design of WPC extrusion dies numerical flow field calculations are increasingly used. Based on rheological measurements, both the shear thinning flow behaviour and the temperature dependence of the viscosity are modelled. In the parallel zone a pure shear flow is present, while in the transition elements such as the flange to the extruder or the mandrel due to the cross‐sectional changes strain rates are dominant. High‐density polyethylene (HDPE) with wood fibers has shear thinning and strain thickening behavior, so different models are needed to describe it. The results of the numerical simulations are compared with experimental values of an extrusion die for a square hollow profile.</jats:p>