Lincoln Electric IM666-A manual Work Lead, Seam Tracking, Welding with Multiple Tandem MIG Systems

A-7 INSTALLATION A-7

WORK LEAD

Minimize the length of the electrode and work lead cables. Do not exceed 50 ft (15m) of combined elec- trode and work lead length.

To make the work lead connection, run a properly sized lead from the work connection on the power source directly to the fixture. The ground connection should be as close to the part to be welded as possi- ble. Do not combine work leads from the lead and trail power source. Each machine requires an indi- vidual work lead to the welding fixture.

Do not tightly bundle the electrode leads or the work leads together. Welding performance may deteriorate.

SEAM TRACKING

Seam tracking is required if the joint position wanders or varies from part to part. Most optical and mechani- cal trackers are compatible with Tandem MIG. Check the manufacturer’s specifications for the seam track- ing equipment. Do not exceed the rated power limit for the seam tracking unit.

Through-the-arc-seam-tracking (TAST) works with Tandem MIG in the same manner as single wire TAST. Perform the current sensing for TAST on the lead electrode.

WELDING WITH MULTIPLE

TANDEM MIG SYSTEMS

Special care must be taken when more than one Tandem MIG torch is welding simultaneously on a sin- gle part. Arc blow and arc interference may occur or be magnified.

Every torch requires a separate shielding gas regula- tor for proper flow rate and shielding gas coverage.

Do not attempt to supply shielding gas for two or more torches from only one regulator.

Use one work lead per power source to connect the work stud to the welding fixture. Do not combine all of the work leads into one lead. Performing welding in the direction away from the work leads. For exam- ple, if there are two Tandem MIG systems welding on the same part, there should be four work leads (two lead and two trail power sources.)

WIRE STRAIGHTENERS

Use a wire straightener with each wire drive. Failure to use a wire straightener may result in inconsis- tent welds and weld bead placement.

TAIL GAS COVERAGE

The Tandem Mig process is capable of establishing wide weld bead profiles at higher than usual travel speeds. When performing large weldments at these high travel speeds the weld pool may become unpro- tected while cooling as the welding torch providing the shielding gas travels faster than the pool cools. To provide weld pool protection during these applications it is recommended to use the trailing gas assembly (M18408-5) to provide additional shielding.

TANDEM MIG TORCH