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

Rapid electrode wear is the major concern in resistance spot welding Of gal vanised steels. The electrode lift irt such instances is tremendously influ enced by the continuous alloying reactions that occur between the molten fr ee zinc and the copper electrodes. It is shown in the present work that the use of compound electrodes can considerably enhance the effective electrod e life. The compound electrodes are fabricated by introducing a tungsten in sert at the tip of conventional circular face electrodes. The performance o f these new electrodes has been investigated under laboratory conditions du ring multispot welding. It is observed that the compound tip electrodes can offer superior electrode life only for a small insert size. A finite eleme nt method based numerical simulation has simultaneously been carried out. T he results of the numerical calculation also indicate that the optimum desi gn of the compound tip electrode depends on the insert size. (C) 2000 IoM C ommunications Ltd.