Prediction Welding Quality in Multi-Pass Welding Process Using Mahalanobis Distance Method
The welding quality in multi-pass welding is mainly dependent on the pre-heating from pervious pass or root-pass welding. In this study, a Mahalanobis Distance and normal distribution method is illustrated and employed to determine whether welding faults have occurred after each pass welding and also to quantify welding quality percentage. To successfully accomplish this objective, sets of multi-pass welding experiment were performed with different welding parameters in each pass; the welded samples of SS400 steel flats adopting the bead-on-plate technique were employed in the experiment. The result of current and voltage for each pass is obtained through the real time mentoring systems. In order to verify the effect of the performance and weld quality of the different weld-pass, Mahalanobis distances for voltage and current values were calculated and used for qualitative and quantitative analysis with comparison to values obtained from the root-pass as reference welds. The results of the experiment and statistical analysis have demonstrated that the weld faults after each weld pass is feasible.