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Thermal direct joining of metal-polymer connections

Presentation held at 9. Internationales Lasersymposium und Internationalen Fügetechnischen Symposium "Tailored Joining" 2016, Dresden, 22.-24.2.2016
: Klotzbach, Annett; Langer, Maurice; Zimmermann, Frieder; Standfuß, Jens; Beyer, Eckhard

presentation urn:nbn:de:0011-n-4048087 (4.8 MByte PDF)
MD5 Fingerprint: 3371c2c32fcb117f45c16f9c6b4aac3a
Created on: 25.11.2016

2016, 22 Folien
Internationales Lasersymposium <9, 2016, Dresden>
Internationales Fügetechnisches Symposium "Tailored Joining" <2016, Dresden>
Bundesministerium für Bildung und Forschung BMBF
Development of laser based joining technologies for dissimilar lightweight constructions
Presentation, Electronic Publication
Fraunhofer IWS ()

In the field of lightweight construction load-capable mixing compounds with the material specific advantages of metal and thermoplastic become increasingly significant. For this efficient process chains including adapted pretreatment and joining processes in combination with process simulation tools are required. Post- or in-mold assembly processes, mechanical joining by screws or rivets and adhesive bonding are state-of-the-art techniques for joining dissimilar materials such as metal and thermoplastics [1, 2]. Specific restrictions can be found at the limited geometry flexibility, the use of additional material and comparable long joining times. Hence new joining solutions are needed. Within this presentation the use of thermal induced joining for metal-thermoplastic parts will be shown. These processes are characterized by short joining times and the substitution of glue, screws or rivets. The key technology to enable high joint strengths is the material adapted surface modification. As a research result the influence of physical and chemical pretreatment will be presented. It could be shown that metal ablation by high power lasers can efficiently generate a macroscopic surface structure, which enables mechanical fastening of the polymer at the metal surface. Depending on the material combination (polymers with or without reinforcements, aluminum or steel) the thermal direct joining process has to be temperature- and pressure- controlled. Using conventional heat plates the joining time is limited by the heat conduction to the metallic partner and the cool-down gradient vice versa. Hence the future development will be focused on laser- or induction-induced heating. This will lead to joining times of only some seconds. Within the presentation the thermal induced direct joining process of metal and thermoplastics will be introduced. It will be shown, that an optimized surface pretreatment enables joints with lap shear strengths of 20MPa and more, depending on the material configuration. By optimizing the heat transfer into the metallic part, the processing time can be minimized up to some seconds.