In-situ manufacturing of metal-plastic composite structures by process combination of hydroforming and injection molding

The application of lightweight structures especially in automobile industry is a major factor for reduction of fuel consumption and related CO2 emissions. Beside the implementation of lightweight materials such as Ultra-High Strength Steel, Aluminum, Magnesium or Fiber Reinforced Polymers there is an upcoming request of Hybrid Materials. Metal Plastic Hybrid Structures are an efficient solution to use the right material at the right place in design space. State of the art regarding production technologies for hybrid structures is that metal components are produced separately in conventional forming processes. These parts are engaged in the molding die and the core injection molding process is only responsible for shaping plastic ingredient and joining. Such process chains are complex and extensive. The paper shows a new approach of the process combination of conventionally metal forming technologies and the application of the fluid plastic from molding process as a forming media in the meaning of hydroforming. By this the aim is a process combination of metal forming and injection molding in one die and one process step to produce high complex hybrid metal-plastic components in an high efficient way. In a first development step deep drawing of sheet metals and injection molding process where combined. By this the plastic melt is also used as forming media in the meaning of hyfroforming and it was successfully merged in one tool and one process. The second development step increased the complexity to a combination of gas forming and an injection molding for tubes and closed profiles. For this process combination the gas forming technology was integrated into an injection molding press. One main challenge in such hybrid structures is the joint strength in interface between the metal and polymer component. To substitute chemical bonding agents, such as Vestamelt®, comprehensive investigation were done in surface structuring of metal tubes, such as sandblasting, knurling and laser structuring.