High pressure forming and injection moulding in a single die: Hybrid lightweight design with metal- and fiber-reinforced plastic tubes

The execution of high pressure forming (HPF) with gaseous or fluid media and injection moulding (IM) within a single die and using one process is a promising approach to solve current needs arising both from lightweight design and the production of complex hybrid parts, as well. High pressure forming makes it possible to manufacture complex closed profiles from a wide range of materials. Injection moulding, in turn, allows the functionalising of these parts through the addition of plastic components. In this way, structural and lightweight design can be combined in an optimal manner. In industrial use, these hybrid parts are hydroformed from extruded aluminium profiles and functionalised with injection-moulded components. Important quality features result from the implementation of the adhesive bond between metal and plastic being a cost driver at the same time. Based on its expertise in processing metal tubes in high pressure forming and injection moulding (HPF-IM) in a single die, the Fraunhofer IWU worked with the TU Chemnitz and partners from industry to refine this procedural combination for use with short and endless fibre-reinforced plastic tubes. Here, the authors provided the fundamentals for the HPF-IM. The aim of this paper is first to outline the development results obtained for combining high pressure forming and injection moulding in a single die, using metal tubes. Next, the researchers describe the process-related challenge and the metal profiles produced, the dies and procedures for gasforming combined with injection moulding (GF-IM) using short fibre- and endless fiber-reinforced components. GF-IM in a single die were performed on both an injection moulding machine with horizontal and a hydroforming press with vertical closing movement.