Lincoln Electric High-Speed and High-Deposition Welding manual How Does It Work?

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

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.

Gas Nozzle

Lead Arc		Trail Arc
		Weld
		Bead
Lead Arc	Molten Weld	Penetration
Penetration	Pool
	Travel
Lead		Trail
Arc		Arc

Partial	Completes
Fill	Fill

	Penetration Past the Root	Wets Edges
The Lead Arc generates the		The Trail Arc places a
majority of the penetration		downward and forward
	and leaves joint requiring	pressure on the weld pool
	additional fill.	for better pool follow and
		wetting along the
		bead edges.

APPLICATION

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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

to create additional fill.

Gas Nozzle

Lead Arc		Trail Arc
		Weld
		Bead
Lead Arc	Molten Weld	Penetration
Penetration	Pool
	Travel
	Lead	Trail
	Arc	Arc

Completed

Fill

	Root	Sidewall
	Penetration	Penetration
The Lead Arc creates the		The Trail Arc is focused in
initial root penetration and		the weld pool providing
the majority of the joint fill.		additional joint side-wall
		penetration and joint fill.

T h e f u t u r e o f w e l d i n g i s h e r e . ®