TAGUCHI-BASED OPTIMIZATION OF GMAW WELDING PARAMETERS FOR JOINT STRENGTH

Abstract

There is a set of process variables that defines the quality of a gas metal arc weld (GMAW) joint. The iteration of these process variables to find the optimum setting is time-consuming and does not have a statistical basis. The Taguchi method of robust parameter design is used to determine the optimum combination of welding current, arc voltage, shielding gas flow rate and travel speed to maximize the transverse tensile strength and minimize the weld defect count of mild-steel GMAW joints. Three replicates per trial (27 specimens) were used in a 3²7 experiment designed by a 4 factor 3 level L9(3⁴) orthogonal array.This was a 3²7 experiment using 3 replicates per trial in the form of an L9 (3⁴) orthogonal array. To estimate the influence of the factors and to determine single response optima, signal-to-noise (S/N) ratios, analysis of variance (ANOVA) and response-table analysis were used, and grey relational analysis (GRA) was applied to solve the conflict between the two response optima in order to select a compromise set of parameters. Of the 12 factors evaluated, the current and the arc voltage were found to be the most significant factors for both responses, contributing 35.28% and 31.06% of the variance in tensile strength, respectively, and 25.47% and 21.72% of the variance in number of defects, respectively, and for both responses were statistically significant at 1% level. Based on the GRA-based compromise optimum of 220 A / 24 V / 15 L/min / 350 mm/min, the tensile strength of 534.4 MPa with an acceptable defect level is predicted. The methodology, equations, and complete statistical processing are explained in detail in this paper, so that the study can be directly repeated using data measured in the laboratory