Modelling of melt pressure development in polymer extrusion: Effects of process settings and screw geometry

Melt pressure is one of the most important process parameters in polymer extrusion and it is also closely related to the product quality. However, it is not directly controllable and is affected in a complex manner by changing other process operating conditions such as screw rotation speed and set temperatures. The ability to predict such parameter would be a powerful tool to aid process design and optimisation. However, only a few practical process models are available to predict the melt pressure based on process settings in polymer extrusion. This paper describes new nonlinear static and linear dynamic models which have been developed to explore the effects of process settings and screw geometry on melt pressure development in single screw extrusion. A computationally efficient linear-in-the-parameters modelling technique was used in model development and the resultant models show satisfactory performance in predicting the melt pressure with good accuracy over a wide operating window.