Optimization of the Resistance Spot Welding Process of Galvanized Steel Sheet Using the Taguchi Method

Resistance spot welding is a process used in the industry for joining of sheets, especially in the automobile and aerospace industries. The complicated behavior of this process must be analyzed to set the optimum parameters to get good quality weld. This paper presents a systematic approach to determine the effects of six welding process parameters i.e. preheating current, squeeze time, welding current, weld time, hold time and electrode pressure on the nugget diameter and tensile shear (T-S) strength of the weld joint of galvanized steel. Taguchi quality design concepts of L18 orthogonal array has been used to determine signal-to-noise (S/N) ratio (dB), analysis of variance and F test value for indicating the most significant parameters affecting the spot welding performance. The plots of S/N ratio are used to find out the levels of factors affecting the process. The results obtained prove that improvement in the quality (8.61 % in the S/N ratio for nugget diameter and 19.50 % in S/N ratio for T-S strength) take place if parameters are set at the optimum level predicted by the Taguchi technique.