Analysis and optimisation of electrode life for conventional and compound tip electrodes during resistance spot welding of electrogalvanised steels

Abstract

Rapid electrode wear is the major concern in resistance spot welding of galvanised steels. The electrode life in such instances is tremendously influenced by the continuous alloying reactions that occur between the molten free zinc and the copper electrodes. It is shown in the present work that the use of compound electrodes can considerably enhance the effective electrode life. The compound electrodes are fabricated by introducing a tungsten insert at the tip of conventional circular face electrodes. The performance of these new electrodes has been investigated under laboratory conditions during multispot welding. It is observed that the compound tip electrodes can offer superior electrode life only for a small insert size. A finite element method based numerical simulation has simultaneously been carried out. The results of the numerical calculation also indicate that the optimum design of the compound tip electrode depends on the insert size.