Advanced Welding Processes: Technologies and Process Control

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Advanced welding processes
Wire
feed
A
Time (ms)
7.7 Mechanism of dip transfer.
Current
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250
200
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50
B C D E F
0
0
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Time (ms)
Current Voltage
7.8 Current and voltage waveforms in one dip transfer mode.
High currents (typically 200–400 A) are required to rupture the short
circuit, but the arcing current is low and the arcing time is usually longer
than the short-circuit time; as a result, the mean current is maintained at a
low level. If the current during the short circuit is excessive, the short circuit
will rupture explosively and metal will be ejected from the arc as spatter.
During normal operation of the process, there is some uncertainty concerning
the exact amount of metal detached during each short circuit. The time
between short circuits, the arc time and, hence, the frequency of transfer,
25
20
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5
Voltage