Analysis of the resin residence time distribution in a pultrusion profile
In the production of lightweight components made of fibre-reinforced plastics (FRP), the reinforcing fibres are continuously impregnated with the plastic matrix in processes such as pultrusion and wet winding. One method of impregnation is injection box technology, for which IKV is developing an experimental method to measure resin residence time and local variations across a pultrusion profile’s cross-section in the project Injectionsbox-Design II.
Advantages of using injection boxes are improved component quality, reduced exposure to volatile organic compounds, and increased productivity by processing highly reactive resin systems. In the preceding project, the geometric influences on the flow field in the injection box were investigated and design guidelines were derived. The findings provide a basis for the design of new injection box cavities, but neglect the influence of the injection strategy and the divergence of the resin residence time across the profile cross-section. These factors, however, directly influence process speed and the formation of deposits, thereby impacting process stability and component quality.
In the current project IKV is developing an experimental method to measure resin residence time and its local variations of resin distribution across a pultrusion profile’s cross-section. To this end, the matrix colour is changed in an impulse-like manner during the process. The resulting colour distribution depends on the existing flow field. Each cross-section has a different colour distribution depending on how far the colour change has progressed. Digital image correlation is used to analyse the variation in colour change for each successive cross-section. This methodology allows investigation of the influence of the injection strategy, injection box geometry, and the use of flat semi-finished products.
© IKVProject data and funding
We would like to thank the BMWE for funding the IGF project (funding code 23502 N) and the project partners for their cooperation.
Project duration: 01.12.2025 – 30.11.2026
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