A Global Model for Fully-Intermeshing Co-Rotating Twin Screw Extruders using Novel Conveying Parameters

Description

Fully-intermeshing co-rotating twin-screw extruders are found in a multitude of applications. Addressing the application, the modular screw configuration is tailored individually to combine required processes, which include melting, conveying, mixing, and devolatilization. In this context, the most critical screw elements are conveying elements and kneading blocks. Moreover, twin-screw extruders are commonly operated in starve-fed mode leading to large proportions of the screw being partially filled. The degree of filling is crucial for devolatilization, mixing, and adding additives and fillers via side-feeders.
Modeling of twin-screw extrusion is essential for predicting the processing behavior as well as optimizing the setup. In our previous studies, we presented novel dimensionless conveying and power parameters for conveying elements and kneading blocks. These universal models permit a comprehensive capture of the complex three-dimensional flow geometry thereby establishing the basis for a global model, which is presented in this work. A network-theory-based simulation routine written in PYHTON provides the global modelling but also the conveying characteristics of each segment. This allows the prediction of fully filled regions, the degree of filling of the partially filled regions, the pressure distribution, and the mechanical power required. A variety of screw configurations were investigated, comprising different combinations of conveying elements and kneading blocks. These differed in terms of their pitch, staggering angles, conveying directions, and other geometric parameters.
Our proposed global modeling approach goes beyond the state of the art and has the potential to rise accuracy for predicting the processing behavior. Therefore, it could be used for many tasks such as screw design, process optimization, process control, and troubleshooting.

Period	23 Sept 2025
Event title	Americas Regional Meeting of the Polymer Processing Society
Event type	Conference
Location	Guelph, Canada, OntarioShow on map