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W A V E F O R M
C O N T R O L
Tandem MIG
High-Speed and High-Deposition Welding
How Does It Work?
The two welding arcs common to the Tandem MIG
process have distinct functions. The lead arc (the
first arc in the direction of torch travel) is operated in
a spray transfer mode. The mode may be either a
special Tandem MIG pulse mode, an adaptive
constant voltage mode or a Tandem MIG power mode.
The lead arc's primary function is to establish initial
root penetration and develop a molten weld pool for
the trail wire. While performing these functions the
lead wire typically accounts for 60% or more of the
total weld metal deposited. The trail arc or second arc
Lead and Trail arc functions for high speed welding
Trail arc is focused on the crest of the pool
created by the lead.
Lead Arc
Lead Arc
Molten Weld
Penetration
Lead
Arc
Partial
Fill
Penetration Past the Root
The Lead Arc generates the
majority of the penetration
and leaves joint requiring
additional fill.
T
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f
u
t
T E C H N O L O G Y
Gas Nozzle
Trail Arc
Weld
Bead
Penetration
Pool
Travel
Trail
Arc
Completes
Fill
Wets Edges
The Trail Arc places a
downward and forward
pressure on the weld pool
for better pool follow and
wetting along the
bead edges.
u
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e
o
f
T M
is operated in a special Tandem MIG pulse mode.
The trail arc's function is to add filler metal to the weld
pool and control the bead characteristics such as edge
wetting, physical contour, side-wall penetration and
weld pool follow speed. The trail arc should be kept
directly in line with the lead arc and focused on the
center of the weld pool. The trail wire melting rate
typically represents approximately 40% of the
process deposition rate. The Tandem MIG trail pulse
waveforms are designed to operate at low voltages
to limit arc interaction and minimize arc blow.
Lead and Trail arc functions for high deposition welding
The trail arc is focused on the middle of the weld pool
Lead Arc
Lead Arc
Penetration
Penetration
The Lead Arc creates the
initial root penetration and
the majority of the joint fill.
w
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l
d
i
n
APPLICATION
to create additional fill.
Trail Arc
Molten Weld
Pool
Travel
Lead
Arc
Completed
Fill
Root
The Trail Arc is focused in
the weld pool providing
additional joint side-wall
penetration and joint fill.
g
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e
3/16
Gas Nozzle
Weld
Bead
Penetration
Trail
Arc
Sidewall
Penetration
®
r
e
.
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