Theoretical and Experimental Study on Die Pressure Prediction in Extrusion of Wood-Plastic Composite

This article presents a theoretical and experimental study on the measurement and prediction of die pressure in the extrusion process of wood-plastic composite (WPC). Die pressure is an important parameter in processing of WPCs as it governs the product strength, quality, and the final output rate, which directly affects the economy of the production. In this research work, a modular die was designed to accommodate for various circular die inserts to produce rod-shaped products having various diameters. Experimentation was carried out to record the pressure for each product. To develop a theoretical formulation for die pressure, two different schemes were considered and modified: non-Newtonian flow and hot extrusion. The comparison of the experimental and theoretical results demonstrated that the experimental values are between the values predicted by the two theoretical schemes. However, it was shown that by applying a correction factor (based on the compaction ratio of die) into the hot extrusion scheme, a theoretical ground can be suggested for pressure prediction in WPC processing. It appeared that the WPC flow in the die resembles more of a plug flow.