Taguchi method of optimization of process variables for ultimate tensile strength of friction stir welded joint of Al-Ce-Si-Mg aluminium alloy plates

Abstract

A novel method of welding known as friction stir welding or FSW has found wide applications in metal joining industries now a days. There are various process input variables which affect the output quality characteristic or response of the weld joint produced. Speed of tool rotation, tool feed and tool pin contour are important input process variables and ultimate tensile stress (UTS) of the FSW joint is the output response considered in this research. The Taguchi method of Design of Experiments type optimization was used to find the level and contribution of each of these input process variables on output quality characteristic of the FSW butt joint produced on plates of Al-Ce-Si-Mg aluminium alloy material. Taguchi L9 orthogonal array type design was utilized to bring down the number of experiments from 27 to 9 for a 3 factor, 3 levels each, analysis. The results of Taguchi analysis indicated that the speed of tool rotation at 1200 rpm, tool feed at 15 mm/min and triangular shape pin tool gave the peak output UTS. The ANOVA tests demonstrated that the contribution percentage of the tool pin contour at 41%, speed of tool rotation at 29%, and tool feed at 22%, showing that the tool pin contour has maximum bearing on the output quality characteristics, i.e., UTS of the FSW joint. The optimum UTS predicted by the Taguchi analysis was 88.29 MPa, whereas the confirmation experiments gave a result of 80.54 MPa, which was well inside the confidence interval predicted by the Taguchi design.