Prediction and optimization weld nugget size in resistance spot welding in low carbon steel using design of experiments

In this study, experiments were designed on the basis of response surface method to determine the effects of current, time and electrode pressure on weld nugget diameter using the Design Expert software. The experimental results were employed to develop a mathematical model which is able to predict linear, quadratic and two-factor interactive effects of these parameters on weld nugget diameter of St12 steel with 0.8mm thickness. Adequacy of the model was checked with the help of scatter diagrams and analysis of variance (ANOVA). The predicted results indicated that increase in current and time at low and medium values increased the weld nugget diameter but at higher values due to interactive effects of parameters their increase caused a decrease in weld nugget diameter. Current increase at constant pressures had a similar effect on weld nugget diameter. The developed model was also used to maximize the weld nugget diameter using the above mentioned software. The optimization results showed that weld nugget diameter obtained a maximum value of about 5.80 mm at 10.64 KA current, 9 cycles and 2 bar electrode pressure.

Keywords:

Spot Welding , Design of Experiments , Response Surface , Design Expert SoftwareIntroduction , weld nugget