A simultaneous forming of aluminium-GRP-aluminium sandwiches could be performed successfully. Using
microscopical investigations, new insights in the forming mechanisms of GRP, when forming simultaneously with
aluminium cover sheets, were achieved. However, challenges in the combined forming arise. Wrinkling in the
flange area is one of the major challenges. In conventional deep drawing the down holder supresses wrinkles in the
flange area. But when forming sandwich cups with thick FRP-layers, high down holder forces would extrude the
FRP from the flange in areas where the drawing direction is perpendicular to the fibre direction. Furthermore, in
the inner cover sheets wrinkling of 2nd order was seen. Following the wrinkling, the GRP was forced to accumulate
or thin out in certain areas. It was seen, that in areas, where the fibre direction is perpendicular to the drawing
direction, the fibre layers start to overlap in order to fill upcoming cavitation. A tool concept with an all-over tool
contact, and thus pressure, is suggested in order to prevent wrinkling in the side wall area. In order to gain further
understanding of the forming behaviour and interaction of the components metal, thermoplastic and fibres a
thorough investigation and further experimental set-ups are necessary. Especially the effects of the temperature, an
appropriate tool concept and simulation models seem to be key factors.