Plastics Processing IKV produces parts from polyurethane matrix in 5 minutes

Editor: Eric Culp

With support from the German Research Foundation (DFG), the Institute of Plastics Processing (IKV) at RWTH Aachen University is working on developing a polyurethane spray process for producing composite parts with high fibre volume in short cycle times.

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The aim of the project is reportedly to create a fast, fully automated production process for fibre-reinforced structural parts that is suitable for large-volume manufacturing. The project is being sponsored by the DFG as part of the Research Unit 860: “New process chains for composites: Integration of preforming, impregnation, forming and curing”.

Compact polyurethanes are used as the matrix material. Not only do they have a wide spectrum of properties, but they also offer many advantages owing to the fact that their reaction kinetics can be adjusted over a broad range.

For production of the composite parts, textile preforms are impregnated with oriented, non-compacted continuous fibres by means of the spray technology. A non-foaming Baypreg polyurethane from Bayer MaterialScience AG serves as the matrix material. A polyurethane spray centre was built at IKV’s Composites pilot plant with the support of KraussMaffei Technologies GmbH.

Application of the matrix and pre-impregnation of the dry preforms, carried out on a vacuum-assisted impregnation tool, takes just 30 seconds. Complete consolidation and cross-linking of the impregnated textile are performed in a newly developed compression moulding tool that is operated isothermally at 100°C and enables excess resin to flow away in controlled side-cavities. The spray process and adapted compression technology in combination produce parts as large as 500 x 500 x 3 mm and having a fibre content exceeding 50% in cycle times under 5 minutes.

The original target was 10 minutes, says IKV. Thus, process time has been more than halved. It is to be reduced further through modification of the polyurethane’s chemical composition.

Institut für Kunststoffverarbeitung (IKV)

Aachen, Germany