A model for melting rate phenomena in GMA welding

The melting of the wire is a fundamental characteristic of GMA welding which influences process stability and productivity, and weld bead shape. The present work describes a numerical model that was developed to calculate temperature distribution along the electrode during welding. This model was adjusted using melting rate and welding current experimental data, and the fraction of vaporised material or the arc heating of the electrode as control parameters. The results from this procedure were compared to data from the literature and used with high speed video image recording of the arc region to present a model to explain the anomaly in the melting rate curve that is observed when welding is performed with constant current (CI) power supplies.