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.
A-7
INSTALLATION
TANDEM MIG TORCH
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.)
Summary of Contents for TANDEM IM666-A
Page 22: ...NOTES TANDEM MIG TORCH ...
