Introduction of an in-mould infrared heating device for processing thermoplastic fibre-reinforced preforms and manufacturing hybrid components

Abstract

Automated production technologies of hybrid structures and components are one key requirement to force the way of lightweight constructions and design into automotive large-scale production. Furthermore, lightweight constructions need to provide additional functionality compared to conventional components to compensate for higher material and manufacturing costs. Therefore, the aim of today’s research is to find economic strategies for automated, function and process integrated final-shape-manufacturing processes. Conventional manufacturing processes for large-scale production are applied in sheet-metal working and plastics processing industries. For this reason, industry and science try to apply the process expertise of these industries on processing fibre-reinforced plastics (FRP). The combination of thermoforming of thermoplastic fibre-reinforced preforms (TP-FRP) with metal sheet inserts and efficient injection moulding processes shows a high industrial potential and at the same time the complexity of transferring the expertise of conventional to composite materials. The complexity occurs because of the differing material properties during the course of the process. The main challenge is the dynamic heat management of the TP-FRP during different process steps. For one thing, the preform must be molten and heated above melting point to perform a shaping process, an adhesive bonding with the injected material and the final consolidation. Conversely, a solidified preform has advantages in material handling and is less sensitive towards outside influences. Existing strategies of heating preforms during the process have several disadvantages. Either the preform must be overheated harmfully to balance the temperature losses or the process becomes inefficient because of the high thermal mass of the mould. Therefore, this paper introduces an integrative approach to apply an infrared (IR) heating device in a mould for processing TP-FRP with gentle and effective heating.