AUTOMATIC PULSED MIG WELDING.

The conditions necessary for optimum metal transfer with minimal fume and spatter were investigated theoretically and by experiment. Effects on the stability of drop formation and arc length of welding parameters (wire feed rate, energy input, voltage, current, pulse times) were established in theory. The equations were confirmed by tests on bead-on-plate and fillet welds in mild steel made using 95%Ar/5%CO//2, 80%Ar/20%CO//2 or 100%CO//2 shielding gas in flat, vertical-down or overhead positions. A photographic technique was used to study metal transfer, drop volume, arc length, number of drops per pulse, spatter and fume. Weld bead shape and root penetration were also determined as functions of welding parameters. A microcomputer control system uses the relationship developed to optimise pulse parameters.