Effect of process parameters and tool geometry on the weld strength of aluminum alloy 1050 during multilayer ultrasonic spot welding

This paper presents the effects of process parameters (welding time, amplitude, and load) and tool geometry (knurl tooth angle (KTA)) on aluminum alloy 1050 weld strength during multilayer ultrasonic spot welding (USW). The study used response surface methodology with analyses of penetration depth, interfacial temperature, and vibration dynamics. Weld strength increased to approximately 500 N. Longer welding times, higher amplitudes and loads, and a medium KTA led to base-metal fracture, along with a higher interfacial temperature and larger penetration depth. Weld strength sensitivity decreased in the order of welding time, amplitude, load, and KTA. Displacement and relative displacement in the vibration direction affected the weld strength, only slightly. The findings of this study provide insights and guidelines for process optimization.