Designing Equipment for Extrusion Lines
Prof. Jose Covas
IPC – Institute for Polymers and Composites, Departamento f Polymer Engineering, University of Minho, 4800 Guimarăes
Portugal

Keywords:

---

Extrusion is one of the major polymer processing technologies, hence it is not surprising that it has focused a significant investigation effort for the physical understanding and the mathematical modelling of the various aspects of the process. The results of this activity, together with the spectacular developments in computer performance, yielded the availability of powerful process modelling tools, which can be used to solve important practical problems, such as defining operating windows, or designing new equipment. However, this is often done in a very inefficient trial-and-error basis, since the software is generally designed for modelling rather than for design purposes.

The authors approach design as an optimisation problem, where the available direct algorithm is used iteratively until the prescribed performance is reached. The method is anchored on three modules: i) a modelling package of the direct problem, ii) an objective function quantifying the process performance (by using the responses provided by the model), and iii) an optimisation algorithm that attempts to maximise/minimise the value of the previous function. Depending on the nature of the problem, distinct algorithms and objective functions have proven to be more appropriate. This methodology is illustrated with three examples: i) single screw design, ii) die design and iii) thermal design of calibrators.