variation of this spray arc technique is known as pulsed spray welding.
In pulsed spray arc welding, the current
is varied between a high and low value. The low level of current is below the
transition current while the
high level is well into the spray arc region. Metal is only transferred to the
work during the period of high current.
Usually one droplet is transferred during each high current pulse. Figure 1-4
depicts the welding current
pattern used in pulsed spray arc welding. In the United States, only 60 or 120
pulses per second are used.
Because the peak current is in the spray arc region, arc stability is similar
to that of conventional spray arc
welding. The period of low current maintains the arc and serves to reduce the
average current. Thus, the pulse
spray technique will produce a spray arc at lower average current levels than
are required for conventional
spray arc welding. The lower average current makes it possible to weld thinner
with spray type transfer using larger sized wire electrodes than otherwise possible.
Pulsed spray arc
welding can also be used for out-of-position welding of heavier sections.
Figure 1-4 - Pulsed
Spray Arc Welding Technique