Effect of tool design and process parameters on lap joints made by right angle friction stir welding (RAFSW)

Abstract

In recent decades, friction stir welding (FSW) has attracted extensive attention of academic and industrial sectors as the most considerable development in metal joining processes. FSW lap joint is an interesting alternative for rivets, fusion welds and bonding particularly in the transportation industry. In this paper, the effect of tool design and process parameters on the generated downward axial force and strength of AA6061-T6 lap joints is studied. The welds are made by a low-cost friction stir welding technique at right angle (RAFSW). The studied tool design parameters are shoulder diameter, shoulder groove depth, pin length, pin angle, pin base diameter and pin lead. Moreover, the effect of tool rotational speed, traverse speed, plunge depth and lap joint configuration is evaluated. The Taguchi method is used to design the experiments and artificial neural network (ANN) modeling is applied to predict the plunging force and the strength of the joints. The results indicate that a quality weld can be obtained at low downward axial forces during welding by proper selection of tool design and process parameters. It is identified that one can achieve a quality lap joint at traverse speeds as high as 1400 mm/min and downward axial forces as low as 3.2 kN by a low-cost RAFSW technique.