Optimization of preform geometry in extrusion blow molding: A simulation approach to enhance material efficiency
As part of the research project ‘Calculation of the strand expansion of the parison during extrusion blow moulding’, an innovative simulation model is being developed that takes into account the swelling and elongation effects. The aim is to precisely predict the preform geometry under real industrial conditions in order to significantly increase material efficiency and optimise production processes.
© IKVExtrusion blow moulding is a process for the production of hollow plastic parts and can be divided into two technological steps: The extrusion of the tubular parison is followed by the shaping of the hollow body by means of blowing air and cooling in the blow mould. The main objective here is to produce a moulded part with the smallest possible and most homogeneous wall thickness distribution. However, especially the deformations of the parison under swelling and gravitational forces are difficult to predict with simultaneous changes of the mould geometry by the wall thickness control and represent a large source of error for the process. Here, numerical flow simulations offer the possibility to support the developer in extrusion blow moulding. While individual sub-steps of the extrusion blow moulding process, such as the flow processes in the mould, can already be simulated with a high degree of reproducibility, the highly complex deformation of the preform after it exits the mould cannot yet be represented.
© IKVThe aim of the current research project “Calculation of the parison swelling during extrusion blow moulding under industrial conditions to increase material efficiency” is the development and subsequent experimental validation of a simulation model to predict the parison geometry taking into account swelling and elongation effects. For this purpose, a model is being developed in the open-source software OpenFOAM (OpenFOAM Foundation Ltd., UK) that can calculate the swelling behaviour under consideration of gravitational forces for different polyolefins, processing temperatures and throughputs with the help of the Phan-Tien-Tanner (PTT) model. For the experimental validation, a segmentation tool is used which enables the quantification of the wall thickness distribution. With the help of an online rheometer, process data is recorded at the blow moulding machine, which is intended to detect the influence of material fluctuations on the swelling behaviour as early as possible in the process. The knowledge gained will support small and medium-sized companies in particular in the design of moulds and in the reduction of rejects during operation, especially with regard to the material fluctuations to be expected with the increased use of post-consumer recyclates.
We cordially invite you to participate in the project as part of the project accompanying committee and to discuss the procedure and the results achieved with us and other participants from industrial companies. Participation is of course non-binding and free of charge.
Project Data and Funding
The research project 22731 N has been sponsored as part of the “Industrielle Gemeinschaftsforschung und -entwicklung (IGF)” by the German Bundesministerium für Wirtschaft und Klimaschutz (BMWK) due to an enactment of the German Bundestag through the AiF. We would like to extend our thanks to all organisations mentioned.
Project Duration: 01.06.2023 – 31.05.2025
Project Partners
