Experimental investigation and optimization of welding parameters on weld strength in friction stir spot welding of aluminum using Taguchi experimental design

Nineteen years ago, the automotive industry started using the friction stir spot welding (FSSW) process in joining metallic parts. The popularity of this welding process became higher every year. In this study, aluminum (Al) 1020 sheets of 2mm thickness were joined with the FSSW process. The effects of FSSW parameters (plunge depth, tool rotation speed and dwell time) on the mechanical properties of weldments were investigated. The mechanical performance of the welds was evaluated by using the lap-shear tensile test. The optimization was done by using the Taguchi method. 'The-higher-the-better' quality control characteristic using the analysis of variance (Anova) method was applied to determine the optimum welding parameters. The signal-to-noise ratio was computed to calculate the optimal process parameters. The percentage contributions of each parameter were validated by using the Anova technique. The experimental results were analyzed by using the Minitab 17 software. The tool rotation speed was found as the dominant welding parameter on the weld strength of aluminum 1020 sheets for the FSSW process. The weld that had been produced with the optimum welding parameters gave a 23% higher fracture load than the initial welds.