Abstract
A review paper is presented on modeling for polymer extrusion for both single screw and twin-screw extrusion. An issue of global modeling is discussed, which includes modeling for solid conveying, melting, melt flow, and co-operation of the screw/die system. The classical approach to global modeling of the extrusion process, which is based on separate models for each section of the screw, i.e., solid transport section, melting and pre-melting sections, and the melt flow section is presented. In this case, the global model consists of the elementary models. A novel continuous concept of global modeling based on CFD (Computational Fluids Dynamics) computations is also presented, and a concept of using the DEM (Discrete Element Method) computation coupled with CFD computations is discussed.
Highlights
Extrusion (Figure 1) is the most important and most massive technology in the polymer processing industry
The fundamental studies on modeling the solid conveying in the single screw extruder with the use of the discrete element method were performed by Moysey and Thompson [47,48] who demonstrated the suitability of this 3D DEM approach for simulating single screw extruders. They presented the procedures for determining the coefficient of restitution [49], which is used as a material parameter in modeling, and performed the first simulations for compacting granules and the pressure/throughput relation in the feed section of the single screw extruder [50]
It was observed that the basis of computer extrusion models are still the early models of solid conveying and polymer melting, and no significant progress has been made in recent years
Summary
Extrusion (Figure 1) is the most important and most massive technology in the polymer processing industry. It is widely used for the production of film, sheet, pipe, and profiles, as well as for specialty processing operations, such as compounding, mixing, granulating, chemical reactions, and more. These operations are applied for most polymeric materials, and extrusion is mainly used for these operations. There are several important functions of extruding machines, polymer transport (from a hopper to a die), polymer melting, pressure generation, material mixing for thermomechanical and chemical homogenization, and, lastly, product forming. Several fundamental books or book chapters have been devoted to an extrusion process, e.g., by
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