Dieless clinching and dieless rivet-clinching of magnesium

Joining by forming of magnesium alloys is restricted by the limited forming capability of magnesium at room temperature. For this reason heating of the parts to temperatures of 220 degrees C or more is required to form connections without cracks. State-of-the-art joining by forming methods (Such as clinching or self-pierce riveting) are usually working with a contoured die as a counter tool. Researches on these joining methods have shown that a minimum heating time of 3 to 6 seconds is needed to achieve connections of acceptable quality. New joining by forming methods working with a flat anvil as counter tool make it possible to decrease the heating time considerably. In this paper two methods - the dieless clinching and the dieless rivet-clinching - and their potential for the joining of magnesium parts shall be introduced in detail. The results of extensive research on the influence between heating parameters and the formation of the connections as well as tensile test done to characterize the strength of dieless joined connections are discussed.