Prediction of metal transfer modes in the GMAW process

The transfer modes in the Gas Metal Arc Welding (GMAW) process determine to a large extent the quality of the welded beam, which is why they are of such great interest to the scientific and industrial communities. This article presents two coupled models that aim to predict the transfer modes in relation to the process input variables: the arc voltage and the welding current. The first is a gray-box model with a phenomenological basis, which is used to obtain the current dynamic, the electrode temperature, the heat generated in the torch and the electrode fusion rate. The second is a black-box model capable of predicting the transfer modes in the welding process, which was developed using system identification theory. The models were validated with experimental data. It is observed that the dynamics of the welding current affect the stability of the transfer mode. It was found that the short circuit and spray modes were more stable, with various points of instability in the transfer of material present in the transition from the globular mode to the spray mode.