Mechanical Joining of Magnesium Components by Means of Inductive Heating - Realization and Capability

The aspect of lightweight constructions becomes more and more important. This particularly applies to the automotive industry which wants to lower the fuel consumption by a smaller vehicle weight. Under this point of view in recent years steel has often been replaced by aluminum alloys. In comparison with this the application of lightweight magnesium alloys, whose specific density is appropriate within the range of plastics, opens further prospects for weight reduction. The pre-condition for this purpose is the supply of suitable joining processes for magnesium alloys, which are universally applicable and offer the maximum utilization of the materials of the joined parts under operating loads. Mechanical joining techniques provide the opportunity of connecting magnesium components homogeneously as well as in material mix. However, the anisotropic deformation characteristics of the hexagonal crystal structure of magnesium at room temperature contain the application for mechanical joining techniques. Only starting from temperatures of approx. 225°C a sufficient plastic deformation and thus a crack-free shaping of the magnesium material is given. Therefore preheating of magnesium substrates leads to a broad extension of deformability and offers the chance to realize a high quality mechanical joint. This article describes a process-safe realization of the mechanical joining operations clinching, self piercing riveting and clinch riveting of magnesium sheets by means of an inductive heating of the substrates in laboratory scale. In this context, feasibilities and limits of the considered joining techniques are shown.