Abstract <p>Nowadays, aluminum alloys can be safely welded by using bobbin tool friction stir welding (BT‑FSW) having various advantages over the fusion welding process. This research work was carried out to evaluate the welding process parameters such as tool rotation speed, tool pin diameter and welding speed affecting the mechanical performances of welded AA 6063 sheets. Taguchi technique was used to analyse the influence of process parameters on the hardness of the welded joint. L₉ orthogonal array and the analysis of variance was employed to investigate the importance of process parameters for their responses. Experimental results revealed that the hardness of the welded joint was improved with increasing the tool rotational speed and tool pin diameter. The hardness was decreased with increasing the welding speed. The analysed results were verified in the confirmation experiments. The optimal hardness value 92 HV was achieved for the welded joint at the 1200 rpm tool rotation speed, 5.5 mm tool pin diameter, and 50 mm/min welding speed. The FSW process was simulated using Abaqus software to compare the results. The microstructure analysis for different zones of the weld joint and scanning electron microscopy for the welded joint was also performed.</p>