Modelling the effects of operating conditions on die melt temperature homogeneity in single screw extrusion

The extrusion process is fundamental to the production of the vast majority of polymer and composite products in the plastics industry. The delivery of a melt which is homogenous in composition and temperature is paramount for achieving high quality extruded products. However, melting stability can be difficult to monitor/control via typical thermocouple measurements as they provide only a single point temperature measurement of melt flow. Previous studies have shown that die melt temperature changes considerably across the die and point based measurements are not sufficient to determine thermal homogeneity. In this work, the die melt temperature profile is monitored by a thermocouple mesh technique and the data obtained is used to formulate linear/nonlinear models to predict the effects of process settings on the die melt temperature homogeneity in a single screw extruder. A static nonlinear polynomial model is developed, which shows a good agreement with the measured data and provides a straight forward approach for investigating the effects of individual processing parameters on the melt flow homogeneity.