Aachen, Germany -- The Institute of Plastics Processing (IKV) at RWTH Aachen University is currently working on the development of a polyurethane spray process for the production of composite parts with high fibre volume contents in short cycle times.
The institute's aim is to develop the fast, fully automated production process for fibre-reinforced structural parts to make it suitable for large-volume manufacturing processes, IKV said in a 23 May news release. The German Research Foundation (DFG) is sponsoring the project.
The matrix material is a non-foaming Baypreg polyurethane from Bayer MaterialScience. For production of the composite parts, textile preforms are impregnated with non-compacted continuous fibres by means of the spray technology, IKV said. A polyurethane spray centre was built at IKV's composites pilot plant with the support of KraussMaffei.
IKV said application of the matrix and pre-impregnation of the dry preforms is carried out on a vacuum-assisted impregnation tool in just 30 seconds. Complete consolidation and crosslinking of the impregnated textile is performed in a newly developed compression moulding tool. This tool is operated isothermally at 100 °C and enables excess resin to flow away in controlled side-cavities.
Through the combination of the spray process and the adapted compression technology, parts can be produced in sizes of 500 x 500 x 3 mm3 with a fibre volume content of over 50 percent in cycle times of less than 5 minutes, IKV noted. The research institute added that the originally targeted process time of ten minutes has been more than halved and the team aim to reduce this even further through modification of the chemical composition of the PU.