Lincoln Electric Tandem MIG High-Speed and High-Deposition Welding - Manual (Page 3)

Tandem MIG
T h e f u t u r e o f w e l d i n g i s h e r e . ®
APPLICATION
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High-Speed and High-Deposition Welding
W A V E F O R M C O N T R O L T E C H N O L O G Y T M
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.
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.
The Lead Arc generates the
majority of the penetration
and leaves joint requiring
additional fill.
The Trail Arc places a
downward and forward
pressure on the weld pool
for better pool follow and
wetting along the
bead edges.
The Lead Arc creates the
initial root penetration and
the majority of the joint fill.
The Trail Arc is focused in
the weld pool providing
additional joint side-wall
penetration and joint fill.
Lead and Trail arc functions for high deposition welding
The trail arc is focused on the middle of the weld pool
to create additional fill.
Lead
Arc
Partial
Fill
Trail
Arc
Completes
Fill
Penetration Past the Root Wets Edges
Gas Nozzle
Lead Arc Trail Arc
Lead Arc
Penetration
Weld
Bead
Molten Weld
Pool
Penetration
Gas Nozzle
Weld
Bead
Lead
Arc
Trail
Arc
Root
Penetration
Completed
Fill
Sidewall
Penetration
Penetration Lead Arc
Penetration
Molten Weld
Pool
Travel Travel
Lead Arc Trail Arc
How Does It Work?