Hybrid materials - Joining of polymers and metals

Technologies for joining metals and polymers play a key role in exploiting the potential of lightweight design while also considering economic factors like production cost and material cost. Hybrid joining offers the opportunity to use the right material at the right position of the structural component. Especially connecting thermoplastic polymers and metals promises great potential for optimum solutions with respect to creating lightweight structures economically. The interphase between the two materials plays an important role in achieving high strength of the joint. The metal part is pre-treated by a laser-process which generates a structure of Cone-Like-Portrusions (CLP) or a line structure on the surface. These structures represent undercuts on a microscopic scale and increase the surface area. During manufacturing the melt penetrates into these undercuts and creates the joint via three different mechanisms: positive locking, adhesion, and friction. The present paper evaluates different sets of process parameters for thermal welding by laser, injection moulding and pressing by means of quasi-static tensile tests. Uniaxial and multiaxial fatigue test results are presented for the most promising sets of process parameters. On a demonstrator part, a roof crossrail from a luxury car, the technology is validated.