Clinching eliminates process-related auxiliary joining elements, resulting in simpler process control, more favorable plant technology, lighter assemblies and the elimination of a third material within the joint. In addition, clinching without a cutting component eliminates notch effects, as they occur with self-pierce riveting. According to DVS guidelines, the use of hybrid joints can also improve the properties of strength, stiffness, corrosion protection, sealing, damping and failure behaviour compared to the pure individual processes. However, the joining of aluminium die-castings and steel sheets by clinching is not currently state of the art in vehicle manufacturing. The clinching suitability of die-cast aluminium was proven in previous research projects using the alloy EN AC-AlSi10MnMg in the heat treatment state T7. Depending on the topography of the material, it was possible to produce flawless joints with high joint strength values after tool optimisation. However, the research project has also shown that further research efforts must be made to further qualify the joining process for large series applications before competition.
The aim of the project is to extend the clinching of die-cast components in such a way that comparatively brittle material states can be clinched reliably and without damage, taking into account immanent material defects (e.g. gas porosity). The clinching suitability of an aluminium die casting alloy (EN AC-AlSi10MnMg) frequently used for structural components is to be investigated in the cast state as well as in various heat treatment states. The assumption of a comprehensible correlation between component porosity and mechanical properties of the die casting alloy, the casting process parameters and the clinching suitability is to be derived. Due to the high application relevance, hybrid clinching tests using structural adhesives as well as final validation tests on real structural components, as they are currently used on the market, are planned for the end of the project. With the project results, clinching system manufacturers can open up a completely new market in the field of light metal casting.
