Linde BOC RAPTOR 160 MIG Operating Manual page 19

Schematic of Dip Transfer
1 Short circuit
2 Necking
3 Arc re-ignition
4 Arc established
5 Arc gap shortens
6 Short circuit
Current (A)
Voltage (V)
MCAW consumables always require an auxiliary
gas shield in the same way that solid MIG/MAG
wires do. Wires are normally designed to operate
in argon-carbon dioxide or argon-carbon dioxide-
oxygen mixtures or carbon dioxide. Argon rich
mixtures tend to produce lower fume levels than
carbon dioxide.
As with MIG/MAG, the consumable filler wire and
the shielding gas are directed into the arc area by
the welding torch. In the head of the torch, the
welding current is transferred to the wire by means
of a copper alloy contact tip, and a gas diffuser
distributes the shielding gas evenly around a
shroud which then allows the gas to flow over the
weld area. The position of the contact tip relative
to the gas shroud may be adjusted to limit the
minimum electrode extension.
Modes of metal transfer with MCAW are very
similar to those obtained in MIG/MAG welding,
the process being operable in both 'dip transfer'
and 'spray transfer' modes. Metal-cored wires may
also be used in pulse transfer mode at low mean
currents, but this has not been widely exploited.
1 2 3
Short circuit cycle
4 5
Time
Arcing cycle
6
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