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The development of thermal joining process for plastics-metal components without filler material, into a hybrid component is a goal of the workgroup "Thermal Joining" in the Cluster of Excellence "Integrative Production Technology for High-wage Countries." In order to develop thermal joining processes, basic knowledge needs to be created. To gain this knowledge a simple machine is created which allows to bond plastic to metal, in a lap joint or butt joint, to a hybrid product. The plastic is locally plasticized and under welding pressure applied on the metal surface. The heat required to plasticize is introduced via heat conduction into the metal. Accompanying to the joining experiments the process is mapped in a simulation. The simulation based imaging of temperature gradients across the thickness of the plastic and the metal part gives valuable insights into details of the thermal joining process.The relative error in the simulation was 1.25%. In addition to the material combinations, classic joining parameters, such as joining temperature, joining pressure or joining time are varied. Different metals such as stainless steel, aluminum and galvanized steel are combined with different thermoplastics like polycarbonate, polyamide and polybutyleneterephthalate. The latter two thermoplastics are also modified with glassfiber. The surface properties of metals have a significant influence on the adhesion quality. To investigate this influence the roughness of the metal surface is modified by sand blasting or it will be provided with undercuts by laser structuring. With optimal choice of parameters a cohesive failure of the plastic partner is possible. The bond strength is determined in tensile tests. Tensile stress at break can be up to 35 MPa. |
