The screw is the heart of both extrusion and injection molding machines. No other component in plastics processing exerts such a decisive influence on product quality and process efficiency. In recent years, it has become evident that the “universal screws” developed in the past often no longer meet today’s requirements. Insufficient melt quality, low throughput, and reduced machine efficiency are driving the plastics industry to explore new approaches. The trend is shifting toward tailored solutions that are specifically adapted to the material, the process, and the product.

However, the complexity of the plasticizing process, combined with the growing number of innovative screw and system designs, makes this topic increasingly challenging. Even today, decisions are often based on experience or experimental trials. As an alternative to the commonly used “trial-and-error” approach, the REX/PSI simulation package was developed. It enables the design and optimization of extruders (REX) as well as injection molding plasticizing units (PSI).

The software runs on a standard PC and allows the simulation and evaluation of key process parameters. In addition, numerous program features support the systematic optimization of individual geometric variables as well as the design of entire machine series.

Since 1989, the simulation programs have been continuously developed as part of a joint research project. By implementing more precise calculation models based on three-dimensional finite element methods and integrating current screw geometries, the software is constantly adapted to the increasing demands of users. These tools therefore make a significant contribution to the evaluation and optimization of single-screw machines in industrial applications.

This user manual provides instructions for operating the software. The theoretical principles underlying the calculations are presented in numerous publications and dissertations. A detailed list of references is included in the appendix.

We would like to take this opportunity to thank all project partners who contributed to the development of this simulation software through their participation in the joint project.

Software Engineering Team REX/PSI (Email: software@ktp.upb.de)

Paderborn