A Study on Prediction of Welding Current in Gas Metal arc Welding Part 1: Modelling of Welding Current in Response to Change of Tip-to-Workpiece Distance

A model of the welding arc in gas metal arc welding (GMAW) is very useful for the analysis and automation of the welding process. Thus a mathematical model that is able to predict the welding current change in response to the variation of tip-to-workpiece distance was proposed for the gas metal arc welding process. The model was deveoped by analysing the welding arc behaviour and by considering the characteristic of the welding power source. The welding current variation was calculated with respect to various welding conditions and slope of the power source characteristic. By comparing the calculated and measured current signals, it could be concluded that the model proposed can well define the relation ship between welding current and tip-to-workpiece distance for various welding conditions in gas metal arc welding. Both the calculated and measured signals of welding current show almost a linear variation in response to the linear change of tip-to-workpiece distance.