Modified Taguchi Approach for Optimal Parameter Selection in Friction Spot Welding of AZ31 Mg Alloy

Abstract

Friction spot welding (FSpW) is a solid-state welding technique that proves highly effective in creating spot-like joints, especially in lightweight materials, thereby offering significant weight-saving potential. This process involves plunging a specially designed, non-consumable and rotating tool, which generates frictional heat and plastic deformation, forming a robust connection between overlapped sheets. Notably, FSpW results in minimal material loss, leading to fully consolidated joints with flat surfaces devoid of keyholes. This study focused on investigating the impact of FSpW parameters, namely rotational speed, plunge depth and dwell time, on the lap shear strength of AZ31 magnesium alloy joints. To achieve optimal results, the input process parameters were optimized using a modified Taguchi design of experiments and Chauvenet's criterion was applied to determine statistically accepted data from repeated tests. Utilizing analysis of variance technique, the study identified the optimal levels of parameters and their respective percentage contributions to the weld strength. The findings revealed that the tool plunge depth exhibited the most significant effect on the weld strength, followed by rotational speed and dwell time.