In the tandem pulsed gas metal arc welding, it is the most important issue to prevent adverse effects caused by electromagnetic interaction between the two adjacent arcs to prevent arc interruption. A pulse timing control can reduce arc interference in tandem pulsed gas metal arc welding. One effective way is to delay the pulse end timing of trailing arc by 0?4-0?5 ms from that of leading arc. In addition, arc length control is assured by pulse frequency modulation for the leading wire and pulse peak modulation for the trailing wire with the pulse timing synchronised with the leading pulse. Consequently, leading and trailing arcs are maintained stable without arc interruption and a stable arc length control is established, which is hardly affected by fluctuations of wire feedrate and extension length.

No abstract

No abstract

In non-pulsed GMA welding, spatter can be reduced by controlling the short-circuit current to a low level just before the re-arcing. The reduction of spatter requires improving the accuracy of predicting the re-arcing by stabilizing the molten metal transfer, and improving the consistency of accuracy against disturbances. The Controlled Bridge Transfer (CBT) process, which optimizes the accuracy of predicting the re-arcing in real time in response to the molten metal transfer, realizes stable, low spatter level GMA welding.

No abstract