Improving the Weld Quality in Gas Welding of Mild Steel Plates : A Taguchi’s Approach

In this paper, weld quality is improved in the gas welding of mild steel plates by using Taguchi’s Design of Experiment (DOE) technique. The strength of the welded joint is strongly governed by the involving process parameters and filler rod selection. Though many factors affect the weld strength, present paper focuses only on the weld speed, oxygen-acetylene gas pressure, torch angle, gap between weld plate and torch tip and gap between weld plates. These parameters are varied to three levels of values and hence L,g orthogonal array is employed. The sixteen different combinations of experiment are conducted in a special type of pneumatic system designed along with a torch holder to control the process parameters accurately. The weld specimens are tested in the Vickers hardness tester and Universal-testing machine. The best value of the weld process parameters is identified from the S/N curves. A validation experiment is also conducted and it is predicted that, the strength of the welded joint is improved by about 2%. ANOVA calculations are performed to identify the individual effect of process parameters on the weld quality. Finally, empirical models are developed to predict the weld strength on the basis of tensile strength and hardness value. The developed empirical models are having good agreement with the experimental results.