Smart process combination for aluminum/plastic hybrid components

The research on lightweight construction increasingly gains in importance, especially for the automotive industry. During the last years, research mainly addressed metal/plastic compounds. Besides weight reduction as one main benefit, additional functionality can be integrated or functional tasks can be distributed: The metal ensures the stiffness and realizes the technical connection to the car body by means of welding, while the plastic enables the insertion of special elements for the joining or assembly process. Within the framework of the MERGE Cluster of Excellence the focus of research was the proof of concept, combining metal forming and injection moulding in one single tool. Several publications have shown the successful application of two different part designs. The sheet-based hybrid process was validated using steel as sheet material. Due to its pleasant properties regarding yield strength and stability a stringent examination of the process and the impact of process parameters was possible. However, recent research activities also focussed the application of materials like aluminium, which show a much more difficult forming behaviour. Due to the lower yield strength of aluminium the conventional process control leads to a significant loss of process stability. Thus, the forming tool was supplemented by an active blankholder, based on hydraulic cylinders. This blankholder realized a free adjustment of the distance between the upper and lower tool half and, thus, of the material movement. With the integration of the active forming tool in a closed loop system an extension of the process limits for aluminium-plastic hybrid components was ensured. The tube based process also focusses the combination of a hydroformed aluminium tube with a plastic structure. Using the results of the examinations, gathered within the last years, a cockpit crossmember is realized for a car application. The paper sums up all recent research results with special respect to the aluminium/plastic combination andl give an overview about upcoming fields of interests.