Manufacturing CFRP sandwich parts using wet moulding

Fibre-reinforced composites are introduced into fabricating car bodies in mass production recently. In order to comply with the increased requirements of automotive manufacturing, production cycle times and production costs need to be reduced. A promising approach is currently under development at BMW Group, involving CFRP sandwich parts manufactured by wet moulding and prepreg pressing. The substitution of a sandwich component for a modular shell construction results in a reduction of the overall production steps and a lesser effort for tooling costs, joining technology, assembly and logistics. This contribution aims at presenting the already acquired knowledge about the process. This includes the influence of core compression and temperature development in the sandwich construction on the characteristics of the face sheets. Additionally, the fabrication of the semi-finished goods is examined individually. Two types of material are utilised to pre-assemble the face sheets: a combination of non-crimp fabric and liquid resin as used in wet moulding and prepregs, which derive from the MAI Autopreg project using filament winding. Due to cost efficiency in mass production, milling of the core has to be replaced by alternate technologies. Recent investigations demonstrate the feasibility of manufacturing near net shape sandwich cores using thermoforming.