So far it has been assumed that when describing the flow process in single-screw extruder, the melt will be wall-adhering. using certain process conditions, however, some materials such as PVCs, high-molecular PEs, elastomers, polymer suspensions, ceramic materials and food products become wall-slipping [1 to 4]. During simulation of the flow process using the Finite Element Method (FEM), the boundary condition of "wall-adhering" was substituted for "wall-slipping". The numeric results refer to one-dimensional, non-Newtonain, isothermal flow processes and have been evaluated accordingly. Since the wall-slipping properties are dependent on critical shear stress, the influence of non-Newtonian behaviour on wall shear stress is illustrated by investigating the barrel and screw root surface. Conclusions with regard to wall-slipping properties may be drawn from the resulting upper and lower limits. The effect of wall slippage on pressure/throughput behaviour is examined along with the various velocity profiles, resulting from differnet compression ratios, dimensionless critical shear stress, material-related constants and screw configuration.
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