Lincoln Electric High-Speed and High-Deposition Welding manual Shielding Gas, Work Lead Connection

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	11/16
High-Speed and High-Deposition Welding

Using Tandem MIG

Understanding Operating Variables

Shielding Gas

The lead and trail shielding gas should be of the same mixture and supplied through separate flow regulators. Gas flow per electrode should be a minimum of 40-cfh each. High deposition procedures may require flow rates as high as 70 cfh per electrode. High deposition multi-pass applications may require that a trailing gas is applied to eliminate nitrogen pick-up. The Tandem MIG process requires a binary gas mixture capable of supporting a spray transfer. Argon/Carbon dioxide or Argon/ Oxygen are the preferred mixtures.

1.90/10%, Ar/CO2 is preferred for most welding applications.

2.82-95% argon with a Ar/C02 binary mixture is a useable range, The higher CO2% will promote added penetration but may produce added spatter. The lower CO2 % will produce less spatter.

3.95/5%, Ar/O2 is recommended for high speed welding of thin gage material under 3mm. The mixture will provide improved wetting at bead edges and reduced tendency to erode away edges of lap welds.

Work Lead Connection

Tandem MIG welding should be performed welding in the direction from the work lead connection. Welding towards the work lead connection may cause a convex weld bead and undercut.

Joint Selection

The Tandem MIG process is ideal for many joint configurations. A joint application rating is as follows:

Excellent

1.Lap welds in the flat, horizontal, 3 o'clock position.

2.Fillet welds in the flat and horizontal positions.

3.Joggle welds in the flat position.

4.Beveled butt welds in flat position.

5."J" Groove welds.

6.Rotated roundabouts, lap and joggle welds.

Good

1.Beveled butt welds in horizontal position.

2.Horizontal flare joint.

Poor

1.Seamer applications.

2.Joints known to be subject to arc blow.

3.Weld joints that have multiple or severe turns in direction or contour.

4.Thin gage square edge butt welds.

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