Interaction Between Foam Injection Molding and Welding Process
- 46 Downloads
Due to increasing demands on component integration, functionalization, saving weight or material, the density and weight of thermoplastic parts could be influenced significantly by using the thermoplastic foam injection molding process.
The characteristic three-layer structure offers numerous advantages for applications, such as weight reduction, increasing the specific bending stiffness with a simultaneous low tendency to warp and optimizing thermal and acoustic properties. For a subsequent joining process, however, difficulties arise due to the thin solid skin layer. Minimum joining distances during welding can no longer be met geometrically and the mechanical properties of the components are reduced.
The present study is intended to analyze the interaction between the microcellular structure of the injection molded parts, the influence on the joining process and the resulting mechanical properties. Therefore, a cooperation of Chemnitz University of Technology and University of Bayreuth was founded to investigate the correlation between injection molding and vibration welding for microcellular polypropylene and polyamide materials.
In addition to various materials with and without fiber reinforcement, the influence of storage time and different joint types were investigated in this study.
The aim of this study was to gain a deeper understanding of the relationships between process, material and its structure as well as the development of processing guidelines which can be transferred to industrial applications.
The results show that the characteristic three-layer structure has a considerable inhomogeneity, depending on the used material, the foaming process and the process parameters.
However, the weldability of foamed thermoplastics strongly depends on the internal structure due to the injection molding parameters, the storage time between foam injection molding and welding process, the joint type and the welding process itself.
KeywordsFoam injection molding Physical foaming Chemical foaming Vibration welding Parameter variation
The investigations were carried out in cooperation of the University of Bayreuth, Polymer Engineering Bayreuth.
The investigations were promoted from budgetary funds of the German Federal Ministry of Economic Affairs and Energy (BMWi) on the basis of a decision by the German Bundestag via the German Federation of Industrial Research Associations (AiF) We would like to record our appreciation of this support.
Furthermore, we thank the companies Lanxess Deutschland GmbH and LyondellBasell Industries for providing the material.
- 2.Okamoto, Kelvin T.: Microcellular Processing. Hanser, Cincinatti (2003)Google Scholar
- 3.Hopmann, C., Kreimeier, S., Schoengart, M.: Laser transmission welding of foamed thermoplastic injection moulded parts. In: PPS – Polymer Processing Society. IKV Aachen, RWTH Aachen University (2016)Google Scholar
- 4.Potente, H.: Schweißen von Thermoplasten mit zellularer Struktur. Final report (AiF – Project 13.595 N), University Paderborn (2006)Google Scholar
- 5.Kishbaugh, L., Kolshorn, U., Bradley, G.: Vibration and ultrasonic welding conditions and performance for glass fiber filled PA 6 and PA 6.6 injection moulded using the MuCell microcellular foaming process. In: Conference Proceedings, Blowing Agents and Foaming Processes (2007)Google Scholar
- 6.DIN EN ISO 6603-2:2002-04: Plastics – Determination of puncture impact behaviour of rigid plastics – Part 2: Instrumented puncture test (ISO 6603-2:2000). Beuth (2000)Google Scholar
- 7.DIN EN ISO 178:2019-08: Plastics – Determination of flexural properties (ISO 178:2019). Beuth (2019)Google Scholar
- 8.DIN EN ISO 527-1:2012-06: Plastics – Determination of tensile properties – Part 1: General principles (ISO 527-1:2012). Beuth (2012)Google Scholar
- 9.DVS-Richtlinie 2203: Prüfen von Schweißverbindungen an Tafeln und Rohren aus thermoplastischen Kunststoffen – Prüfverfahren – Anforderungen. DVS-Verlag, Düsseldorf (2003)Google Scholar