Session 2 of the 33rd IKV Colloquium focuses on thermoplastic foam injection molding as a sustainable manufacturing process for automotive applications.
IKV is researching the substitution of non-recyclable material composites in soft-touch applications through the use of foamed thermoplastic elastomers (TPE) in the automotive sector and is dedicating a special session to this topic at the 33rd International Colloquium on Plastics Engineering.
The special process of thermoplastic foam injection moulding (TFI) has great potential to significantly reduce material consumption and energy demand for injection-moulded components. The Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University, conducts research on how to replace non-recyclable material composites in soft-touch applications by the use of foamed thermoplastic elastomers (TPE) in order to meet future recycling requirements under the End-of-Life Vehicle Regulation (ELV).
Conventional multi-component soft-touch components often consist of a thermoplastic carrier, polyurethane (PU) foam and a decorative layer, which may be made of polyvinyl chloride (PVC) film or nappa leather, for example. In this case neither joint mechanical recycling nor separation of the different material classes prior to recycling are possible.
In the “Foam2Cycle” project, which is funded by German Federal Ministry for Economic Affairs and Energy, IKV is investigating the production of soft-touch applications using TPE foams manufactured via TFI (Figure 1). Applying a two-component injection moulding process, soft-touch components are produced that offer the following advantages:
© IKV- Manufacturing in a single, closed process
- Constructed exclusively from thermoplastic components that can be recycled together
- High-quality surfaces thanks to a customised injection moulding process
- Cost-effective production compared to conventional soft-touch composites
Results from the project will be presented at the 33rd International Colloquium Plastics Technology in Aachen in Session 2: Circular products through foam injection moulding.
A question of timing in negative embossing
During the production of the soft-touch component, the TPE component is foamed by means of a negative embossing stroke. To achieve this, the mould is partially opened after full volumetric filling, allowing the foam to expand by the controlled cavity opening. Setting up this negative embossing stroke is not trivial. Factors such as delay time, mould wall temperature, opening distance and opening speed have a significant influence on the resulting foam structure and the achievable foaming degrees of the TPE. If the process is not carried out properly, defects such as a torn foam core or insufficient foaming may occur (Figure 2). At IKV, the interactions between these parameters were identified and parameter windows were defined that can be used to produce a homogeneous foam morphology with high foaming levels.
© IKVCharacterisation methods for TPE foam haptics
The quality of TPE foams depends not only on the aforementioned set-up parameters, but also on material fluctuations and environmental conditions. Quality testing is therefore crucial to ensure consistent component quality during production. However, due to the short cycle times of the injection moulding process, the testing time available for in-process control is very short. For this reason, the material behaviour of TPE foams is being investigated in order to understand the significance of certain quality characteristics. Based on these investigations, an optimised test method for indentation tests is being developed in order to obtain relevant information about foam quality within the limited time of a production cycle. The test method is to be evaluated in a real-world application in order to validate the significance of the individual parameters in a production environment.
Circular economy at the 33rd International Colloquium Plastics Technology
The colloquium will address the topic of circular economy and recycled material use in several sessions:
- Session 1: Additives, de-inking, coating – building blocks for increasing the use of recyclates
- Session 2: Circular products through foam injection moulding
- Session 6: Mechanical recycling of CFRP: Vitrimers as enablers
- Session 7: Analysis and improvement of the quality of polyolefin recyclates
- Session 12: Processing and recycling technologies for polyurethanes
- Session 14: Processing of recyclates in film extrusion)
At ‘IKV 36 – Research Live’, IKV scientists bring the topic to life at various stations in the IKV technical centre.