The optimization of process parameters for friction spot welded 7050-T76 aluminium alloy using a Taguchi orthogonal array

Friction spot welding is a solid-state welding pro- cess suitable to obtain spot like-joints in overlap configura- tion. The process is particularly useful to weld lightweight materials in similar and dissimilar combinations, and therefore an interesting alternative to other joining techniques (rivets, resistance welding, etc). In the current study, the effect of the process parameters, such as plunge depth, plunge time and rotational speed, are investigated in order to obtain the highest lap shear force. The Taguchi method was used, as well as analysis of variance to study the importance of each working parameter. The results show that the plunge depth is the lead- ing parameter in order to obtain the best lap shear force. An analytical model was used to predict the optimum perfor- mance of the design, based on the optimal parameter. Confirmation tests were carried out to evaluate the agreement between the predicted and the experimental values. The frac- ture surface of the best condition obtained was investigated using scanning electron microscope (SEM).