Observation of metal transfer in plasma MIG welding process

Abstract

Metal transfer behavior in Plasma MIG welding process was observed by means of shadow graph method. Laser system was used in order to eliminate the arc effect, and the metal transfer was clearly observed by using high speed video camera. In this study, metal transfer in conventional MIG welding was also observed for comparison between both processes. As a result, under the same MIG current setting, the transfer type for both Plasma MIG welding and conventional MIG welding were observed to be in different mode, in which Plasma MIG welding behaved as a globular mode, whereas conventional MIG welding has already became spray mode. It is suggested that, the presence of plasma current in Plasma MIG welding process affected the MIG current distribution for not concentrated at wire tip but dispersed to some ranges on wire between plasma electrodes and wire tip. These phenomena which led to the dispersion of force concentration resulted in a lower transfer frequency and bigger droplet size. These factors then were identified as dominant factors that influenced the droplet temperature.