Numerical simulation of free-flight transfer by a 3D metal transfer model

Abstract

The gas metal arc (GMA) welding process involves metal transfer, in which molten droplets detach from the tip of the electrode wire and move to the base metal. Such metal transfer influences the arc plasma behavior, and affects the performance and productivity of the entire welding process. Therefore, controlling metal transfer is important for improving the welding process. However, metal transfer is not understood sufficiently because of its complexity. The objective of the present study was to obtain a deeper understanding of the metal transfer process, and we performed a numerical investigation to visualize 3D metal transfer. We focused on the free-flight transfer that is observed under relatively high-voltage conditions and the influence of the current path on the transfer mode was investigated. In order to simplify the calculation model, we did not take into account the arc plasma. We assumed a conical current path from the wire electrode to the cathode plate in order to include the electromagnetic force. The model could numerically describe the straight mode with a fixed hypothetical arc. On the other hand, when the arc moved temporally, the tip of the liquid swung and generated small droplets similar to spatter, likely as a result of rotating transfer. The current path was found to play a very important role in determining the metal transfer mode.