EFFECT OF MULTI-RESPONSE PERFORMANCE CHARACTERISTICS ON OPTIMUM PLASMA ARC WELDING PROCESS PARAMETERS
DOI:
https://doi.org/10.4314/njt.311.101Keywords:
weld strength, process parameters, PAW, ANOVA, Taguchi method, grey relational analysisAbstract
A significant number of failures that occur in metal structures usually occur first at welded joints. Weldments are usually of lower strength than the parent metal because of certain factors such as the presence of pores due to entrapped gases, overheat treatment due to prolonged welding, brittleness of the weld as a result of weld metal oxidization, and possibly poor quality welding from operators’ lack of skills. However, these inadequacies can be corrected by altering the process parameters aimed at optimizing the welding. In this research, the process parameters were optimized by applying the Taguchi method along with the Grey relational analysis. From this analysis, an optimum combination of process parameters is obtained. The optimum combination of A1B3C3D1; a torch stand-off of 4.5mm, welding current of 220A, welding speed of 500 mm/min and plasma flow rate of 2.2 litres/min, were the optimum plasma arc welding process parameter combination obtained in this study. The resulting optimal combination was further investigated by applying the Analysis of Variance, ANOVA, to show which welding process parameter significantly affected the performance characteristic of the welding process. From the ANOVA, the torch stand-off, welding speed and plasma flow rate were found to be the primary contributing factors that greatly influence welding performance whereas the welding current was considered a secondary factor. The confirmation test shows that the proposed optimum process parameters are 1.41 times better in terms of the fracture strength of the weldment, than the existing parameters. This indicates that the multiple response performance characteristics are greatly improved through this study.Downloads
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