Variation Manager


User defined


Scale-Up Module


Fast computing times

REX – computer-aided extruder design

REX enables the fast and comprehensive assessment of the machine behavior and thus creates the possibility to perform an optimization of barrel and screw configuration as well as of the process parameters. This goal is achieved by implementing predominantly analytical and closed-form equations. Computationally intensive numerical methods are avoided as far as possible.

Graphical user interface

The results of the simulation calculations can be output graphically in the form of diagrams as well as in tabular form. This graphical output is designed to show the progression of a variable over the screw length. This type of plotting makes it possible to evaluate individual screw zones.


Calculation options

Pressure and throughput calculation

Melting calculation

Calculation power consumption

Calculation of residence times

Calculation of the temperature profile

Calculation of the trickling behavior

Mixing index calculation

Calculation of the shear rates in the process

Calculation of the residence time behavior

Calculation of polymer blends and polymer-filler compounds

REX - Computer-aided Extruder Design is a joint research project in which about 20 industrial companies (references) and the KTP of the University of Paderborn are currently involved. The aim of the project is the ongoing further development of the REX simulation software of the same name, which can be used to calculate plastics processing operations on single-screw plasticizing units.

Features in detail

In addition to the process calculation, REX offers further program functions that support the user during process optimization.

Variation Manager

The Variation Manager can be used to analyze the influences of changing individual or several parameter variations with regard to geometry, material or process parameters. For example, the influence of the passage depth of the metering zone on the pressure curve and the throughput of the entire process can be evaluated. For this purpose, the curves of the changed values can be directly compared with those of the initial process using a so-called multi-graph and in tabular form.


User defined functions

Furthermore, it is possible to calculate user-defined functions. Here, values calculated internally by REX can be used to determine your own company-specific characteristic values. This facilitates the calculation of these values to the extent that, for example, the material characteristic values are always selected for the respective state in the process.


Scale Up

The scale-up module is used to transfer processes to machines with larger or smaller diameters. Starting from a model process, the geometry of the main design and the associated process parameters are calculated on the basis of transfer rules. The starting point for scale-up is any process that can be calculated.

Fast computing times

The software is based on an analytical calculation algorithm, which guarantees extremely short calculation times. In contrast to complex finite element simulations, even complicated geometries are calculated quickly in just a few seconds.

Technical details

Supported barrel designs

  • Smooth bore barrels
  • Degassing barrel
  • Grooved bush barrels
  • Cavity mixing elements

Supported screw sections:

  • Feeding, Compression, Metering, Barrier Maillefer, Barrier, Decompression, Wave, PIN section
  • Conical -, Maddock-, Troester , Spiral-, Cylindrical shearing section
  • Cross hole, Faceted mixing and toothed mixing section

Simulations of plastics processing are subject to constant adaptation of requirements and their technical implementation. In the context of advancing digitalization and the fourth industrial revolution, the networking of processing operations is more in focus than ever before.

The joint project on computer-aided extruder design, in which around 20 industrial companies and the KTP are currently involved, is used for the process engineering design and evaluation of the machine behavior of single-screw plasticizing units.

As part of a further development of this existing REX simulation software, REX-Live offers a simulation environment that enables the process behavior to be assessed in real time. The simulated target variables are then visualized to the operating personnel directly on the control panel on the processing machine in graphical form. This display offers the advantage that the results can be assessed directly and, in the case of a machine behavior that needs to be optimized, a recommendation for action to improve the process behavior can be derived.

These goals are initially achieved by the repetitive reading of the process parameters currently present at the plant and the subsequent simulation of the process behavior in real time.

The calculation is based on the same predominantly analytical equations as in the REX software, so that all calculation options implemented there are also included in REX-Live. After the simulation has been completed, the results are finally made visible to the operating personnel and can be used to improve the process behavior.
The innovation of the live simulation enables the user to simulate a process with changed conditions compared to a currently running reference process and to investigate the effect of the changed process conditions on desired target variables.

Process simulation in real time

REX-Live offers the user a simulation of the process behavior in real time. This offers the advantage that the current machine behavior is mapped live and the operator is quickly alerted to any process fluctuations. The influence of possible fluctuations on the desired target variables can thus be directly examined and mapped.

Visualization of the process behavior

In addition to the live simulation, the results are displayed to the operator in graphical form directly on the machine. Furthermore, the established representation of a target variable via the screw length is used to evaluate individual screw zones separately from each other. Thus, among others, the following calculations can be performed:


  • Pressure and throughput calculation
  • Melting calculation
  • Calculation of the temperature profile
  • Calculation power consumption
  • Calculation of residence times

Visualization of the pressure profile

Visualisierung des Aufschmelzverlaufs

How can I purchase the software?

Our software products are not subject to a classic licensing model. Rather, we aim to advance the development of the software together with our partners. This means that we conduct joint research projects in two-year terms, in the context of which the rights of use for the respective software product are agreed.


PAM - Paderborn
Material database

The Paderborn Material Database is a software tool for managing and evaluating material data in the field of plastics technology.


F. Knaup, M.Sc.

F. Knaup, M.Sc.

Project Manager REX/PSI

Kunststofftechnik Paderborn gGmbH
Universität Paderborn
Pohlweg 47-49
D-33098 Paderborn

Tel.: 05251/60-3837

1 + 2 =


Felix Knaup REX PSI

F. Knaup, M. Sc.

Project Manager REX/PSI

Kunststofftechnik Paderborn gGmbH
Universität Paderborn
Pohlweg 47-49
D-33098 Paderborn

Tel.: 05251/60-3837

5 + 2 =