Numerical study on the effect of electrode force in small-scale resistance spot welding

Since electrode force is an important process parameter in small-scale resistance spot welding (SSRSW), its effects on the electrical, thermal and mechanical behavior of the welding process when using direct current have been studied numerically in the present paper using the finite element method. The variations of contact radius, current density distribution and temperature profile at the sheet/sheet (S/S) and electrode/sheet (E/S) interfaces, the threshold weld times and the maximum diameters of the weld nuggets under three different levels of electrode force are investigated. The calculated results show that increasing electrode force will increase the contact radius at the contact interfaces and decrease the welding current density, and hence delay nugget initiation and growth. Increasing electrode force also decreases the cooling rate at the nugget center after the welding current is turned off.