Manufacturing of hybrid gears by incremental sheet-bulk metal forming

The weight of automotive components has to be reduced and additionally a higher integration of functions is aspired. In the case of geared components, the incremental sheet-bulk metal forming technology enables the manufacturing of load- and weight-adapted functional parts. Due to locally adapted mechanical properties by strain hardening, the subsequent conventional hardening and heat treatment can be avoided for certain cases. However, with the application of high strength steels, the strain hardening reduces the tool-lifetime of the filigree gear forming tools. One possibility to increase the tool-lifetime and also the possible gradient of the mechanical properties can be provided by the manufacturing of hybrid gears. In this case, a stack of aluminum and steel sheets with different initial diameters is joined by the combination of a consecutive edge-thickening and gear forming process. This paper presents the experimental results. A reduction of the tool-load by 20-30% compared to the monolithic process was achieved. Furthermore the metallographic investigation proves the coexistence of a form-fit and force-fit as the resulting joining-principle.