Lincoln Electric High-Speed and High-Deposition Welding Lead Arc, Trail Arc, Torch Positioning

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

APPLICATION

Tandem MIG	10/16
High-Speed and High-Deposition Welding

Using Tandem MIG

Understanding Operating Variables

The general rules governing operating variables for single wire GMAW arc welding also apply to Tandem MIG welding. However there are additional considerations that must be kept in mind when welding with multiple arcs. Since the two arcs will interact, the type of power fed to each arc, the wire feed speed ratio between lead and trail, the arc lengths, the wire positioning, and torch angles must be set correctly. The enclosed procedures are starting points and may need to be altered based on specific application conditions. Adherence to the following guidelines will assist in achieving the maximum potential of the process.

Lead Arc

The lead arc creates the majority of the penetration and should represent the majority of the total deposition rate of the process. When using like diameter electrodes for the lead and the trail, the lead should represent approximately 60% of the total wire feed. In the case where a larger wire diameter is used as a lead (for added penetration) the lead should represent approximately 60% or more of the total deposition. The lead arc can be operated in a Tandem pulse, CV or Power mode. Pulse is recommended for the high deposition procedures. Power mode or CV may be used for greater lead arc stability in high travel speed applications.

Trail Arc

The trail arc is used to cool the weld pool and control the bead contour and is always operated in the Tandem pulse mode. The trail should be kept directly in line with the lead arc and focused on the center of the weld pool. The trail wire should represent 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.

Torch Positioning

Torch positioning may be altered for specific applications. A 5-degree push angle is recommended for high deposition welding. A (0-5)-degree angle is recommended for high speed welding.

Travel Angle	Joint Angle
Push Angle
Push Angle
	90°
		65°
	Flat Welds	Horizontal Welds
	(Beveled Butt, Fillets, Laps	Lap
		1/2” Wire Dia.
Travel		40°
Directionl	45°
A 5-degree push angle	Horizontal Welds	Horizontal Welds
is recommended	Small Fillet	Large Fillet

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