Optimization of weld pitch on overlay welding using mathematical method

It is important to overlap the even bead continuously to automate the overlay welding process. To obtain the even surface bead on overlay welded product, optimization of pitch distance between the each pass is one of the methods. Therefore, this study determines the optimal second pass pitch distance with respect to welding parameter such as torch position and welding speed. Variety of welding experiments was carried out with different welding parameters using Central Composite Rotatable Design (CCRD) method. Based on the experimental results, empirical models were developed after analyzing correlation between welding parameters and bead height, width and decentration of overlay welding. Finally, optimized empirical models were developed for predicting bead height and width by analyzing the main effect of each factor which affects bead geometry and their influence on interaction. In addition, a mathematical model was developed which determines the bead profile for visualizing the bead shapes using the Matlab curve fitting tool. These two models were combined for one of the overlay bead shape model. Furthermore, the mathematical model is then used to determine the second pass pitch distance, by allowing the same area above and below the point of interaction between two overlay weld pass.