Experimental and numerical investigation of process force evolution in Ultra-High Rotational Speed Micro FSW

A variant of Friction Stir Welding (FSW) called Ultra-high rotational speed micro friction stir welding (UHRS mu FSW) is proposed for welding thin sheets. Experimental and numerical investigations are carried out to study the effect of ultra-high tool rotational speed on the process force. Studies conducted on softer AA1100 and stronger AA5052 alloys show that the axial force is reduced by 62.7% on increasing the tool rotational speed from 3,000 rpm to 24,000 rpm in AA5052 alloy, whereas the decrease is 52.8% in AA1100 alloy. It is discovered that the plunge depth is the most important process parameter - after tool rotational speed - influencing the process force. Results from the current study prove that UHRS mu FSW is an effective method for joining thin metal sheets. Due to the low process force, the proposed variant can help to develop cost-effective FSW welding robots and portable FSW machines.