Full Product Manual

77
All MIGs have a preset inductance that is inherent in the
machine’s design. However, few MIGs have an adjustable
inductance. Inductance is part of the personality of a MIG
welder. It’s one reason that some people prefer the arc of
one brand over the other as people develop personal prefer-
ences in arc performance. With that in mind, having an
adjustable inductance serves several functions:
1) The inductance allows the user to dial the machine to a
performance level that the user is accustomed to. This
helps if multiple users are present and improves the
operator’s performance with the welder.
2) The inductance can help improve control and weldabil-
ity in out-of-position welds (weld positions other than
flat) without having to change other parameters.
3) Different shielding gases require different levels of in-
ductance for optimum performance. The inductance
improves performance with different gas mixes by being
able to adjust the setting to render the best and
smoothest possible arc for the shielding gas being
used. This is especially helpful when pure CO2 is used
when less inductance is used for spatter control.
4) The inductance can improve weldability of thinner met-
als without having to step down a size in wire. While
ultimately there are limits to what any given wire can
weld on the lower end of it’s range, it does help im-
prove the low amp welding characteristics of the wire
diameter.
For the best possible experience welding with Lightning
MTS welder, adjust inductance after the wire speed and
voltage have been tuned. This will keep the user from con-
stantly having to hunt for the best balance of the other two
adjustments. Usually once a particular inductance setting is
selected that is suitable to the user, it will work well through-
out the range of adjustments and will rarely require readjust-
ment once set to the operator’s satisfaction. However, this
is not to say that readjusting the inductance from time to
time is not benecial. When the operator must weld out-of-
position, readjusting the arc force control can help reduce
clogging of the nozzle and even make the puddle more con-
trollable. Welding extremely thin materials such as muffler
tubing can also benet from a lower inductance setting.
Avoid the setting inductance control at any extreme setting
without performing a few test welds rst. Few users will nd
these settings to their liking. Turning the inductance to the
minimum setting does not turn the feature off. A suggested
starting point would be approximately 70% with mixed gas
on steel. This will usually produce a desirable arc with for
most people and will produce minimal spatter. Fine tune the
adjustment from there, increasing in half increments to nd
the best performance.
Burn Back Control.
After the trigger is released on the welder, it’s natural for a
small extra amount of wire to coast out of the gun. This
small amount of extra wire may stick fast in the weld as the
molten puddle begins to cool. This will require the operator
to break it loose and spend time trimming the wire. Even if
the wire does not stick in the puddle, it will often be left
sticking too far out from the contact tip for a proper restart.
Trimming is usually required with a pair of MIG pliers or wire
cutter before restarting the arc. With burn back control,
however, the arc can be kept energized long enough to con-
tinue supplying power to the wire long enough to burn the
wire back to the desired length after the wire stops feeding.
The timer control located under the cover sets the length of
time the that the arc remains on after the trigger is released.
If the burn back control is set too long it can cause the wire
to burn back into the tip itself and welding of the wire to the
tip. Begin with setting the unit for a little less than a quarter
second. If the burn back control is set correctly, it will leave
about 1/4”-3/8” wire sticking out beyond the contact tip. If a
large ball develops on the end of the wire, reduce the burn
back time so that it creates a balance between ball size and
stick-out. Set a Post-Flow that is at least equal to the burn-
back time This helps control balling and prevents oxidation
during burn back. This is a unique feature that is not found
in many welders with burn back control. Burn back control
without post flow can cause erratic restarts due to the oxi-
dized or over-balled wire tip.
Even with the burn back control properly adjusted, due to
operator error, an occasional quick trim of the wire may be
necessary for best arc starts. But overall, when used in a
production setting or in a fabrication shop, the burn back
control can save on labor and aggravation.
Starting the Arc and Welding.
Starting the arc is a relatively simple process. Before begin-
ning, the wire should initially be trimmed to between 1/4 to
3/8”. Once the wire is trimmed, the gun should be rmly
grasped to prevent a phenomenon often referred to as
“machine gunning”. A light grasp, especially at start, can
cause the arc to stutter as the wire pushes back on the gun,
lengthening the wire stick-out and creating an irregular start
and a porous weld. If the arc stutters too much with a rm
grip, lower wire speed, or decrease inductance.
The end of the wire should be positioned just barely above
the metal when the trigger is pulled for the cleanest start.
This will position the end of the contact tip about 1/2” above
the weld. The gun should be in the vertical position, with no
more than 5 degrees lean in either side to side direction.
Holding the wire too far off from the metal will result in
rough starting and too long of wire stick out.
Once the arc has been established, the gun can then either
be pushed or pulled in the direction of the weld. In either
case, the gun nozzle should be positioned directly over the
weld without angling the wire to one side or the other of the
MIG OPERATION AND THEORY
Section 3 Setup Guide