Investigation the effect of bobbin tool geometry in friction stir welding of aluminum alloy 6061-T6

The purpose of this study is to investigate the effect of using bobbin tool on the mechanical properties of aluminum alloy 6061-T6 in friction stir welding. The friction stir welding method is one of the suitable process to welding aluminum alloys to reducing welding defects and increase joint strength. In this process, the welding parameters such as the rotational speed of tools and travel speed, beside the type and geometry of the tool also has a great effect on the quality and strength of the weld. In this study by using the typical tool and bobbin tool the effect of welding parameters on the mechanical strength of the welded joint are investigated. The results of this study show that the bobbin tool has a higher performance and capability in connection with this type of alloy. The main advantage of the bobbin tool is welding the both sides of the weld zone at one stage of the welding process compared to the typical tool. Also in terms of mechanical strength of connection, the use of bobbin tool has resulted in improving the tensile strength of the connection and resistance to a better impact. The effects of welding parameters show that by increasing the rotational speed of the device from 900 to 1100 rpm as well as increasing the travel speed of the tool from 25 to 32 mm/min of the joints shear strength has increased.