2009 Volume 27 Issue 2 Pages 45s-49s
New coaxial plasma GMA welding system has been developed on the purposes of improvement of weld bead, reduction of spatter and fume generation. Welding power sources of GMA and plasma, wire feeding equipment and coaxial plasma GMA welding torch are described in detail. The metal transfer of plasma GMA welding is observed and compared with that of pulsed GMA welding. Although metal transfer in plasma GMA welding and pulsed GMA welding is globular transfer, plasma GMA welding shows smooth metal transfer than that in pulsed GMA welding. Low spatter and low fume welding is realized. The plasma welding current shows high effect on the melting characteristic of Al-Mg alloy wire (A5183-WY), however it shows low effect on that of the mild steel wire (YGW-15). The effect of plasma welding current on bead shape and penetration is examined by bead on plate welding using 4.0 mm thickness Al-Mg alloy sheet and lap joints using 3.2 mm thickness mild steel sheets. With the increase of plasma welding current, the weld bead becomes wide and flat.