Optimization of Ultrasonic-assisted Friction Stir Welded using Taguchi Approach

Friction stir welding process (FSW) is a solid-state welding technique which has several unique advantages. On the other hand, FSW process has some limitations such as low speed and high torque which limit the productivity and applicability of the process. To overcome these limitations, several secondary energy sources were integrated with FSW process. In the present paper, FSW was assisted by ultrasonic vibration energy in a process known as ultrasonic assisted friction stir welding (UAFSW). This paper aims to optimize the main process parameters of UAFSW process using 4 levels for each parameter with a total number of 16 experimental trials using Taguchi technique to help welders to select the proper parameters to achieve the highest efficiency of the joint in terms of the ultimate tensile strength (UTS). The parameters to be optimized are vibration amplitude (20-80 𝜇𝑚), traverse speed (40-160 mm/min) and tool rotational speed (630-1200 rpm). In addition, ANOVA analysis was utilized to determine the contribution percentage of each process parameter. The effect of each process parameter on the UTS was also investigated and analyzed. The results showed that the optimum condition is 20 𝜇𝑚, 80 mm/min, and 800 rpm. ANOVA analysis demonstrated that the rotational speed is the most significant parameter. An UTS of 290 MPa is predicted by the model, where the actual value is 297 MPa with an error percentage of 3.5%.