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Section 3
General Setup of Amps and Volts.
When welding in standard with the Lightning MTS, the two
main functions that require adjustment are Voltage and Wire
feed speed. The function of voltage in MIG welding is to
control the overall width and to a great extent, the height of
the weld bead. In other words, voltage controls the bead
profile. The wire feed speed directly controls the amps, and
in turn amps control penetration. When setting the welder
up you will notice that the WFS (Wire Feed Speed) is dis-
played in Inches Per Minute. For MIG, Amp output is con-
trolled with through control of the wire speed, so one is
related to the other. But Amps are not exactly the same
thing since wire feed speed, wire diameter, and wire type all
figure into the Amp equation. The relationship between wire
diameter, wire speed and amps is easily figured with the
following approximate industry conversions for steel:
.023": 3.5 x Amps = Inches per minute (IPM)
.025": 3.1 x Amps = Inches per minute (IPM)
.030": 2 x Amps = Inches per minute (IPM)
.035": 1.6 x Amps = Inches per minute (IPM)
.045": 1 x Amps = Inches per Minute (IPM)
To convert wire speed (IPM) into approximate Amps, use the
following conversion formula:
.023": IPM ÷ 3.5 = Amps
.025": IPM ÷ 3.1 = Amps
.030": IPM ÷ 2 = Amps
.035": IPM ÷ 1.6 = Amps
.045": IPM ÷ 1 = Amps
Keep in mind these are approximate conversions and do fall
off in accuracy as amps are increased into the upper current
limits for the given wire diameter.
Even though you will find general recommendations about
setting the Amps, Volts and even shielding gas through a
variety of free downloadable apps and online calculators,
every filler metal manufacturer has its own specific parame-
ters for Volt and Amp settings for each wire diameter and
class of wire. The ranges of volt and amp parameters gener-
ally varies somewhat from brand to brand, so be sure to read
the packaging and/or manufacturer literature to determine
what range of settings are recommended. The wire diameter
also limits the practical maximum thickness of what can be
reasonably welded. The issue with following charts, graphs
and calculator recommendations is that most people find
them either too hot or too cold. For some people, it may not
even close. However, nothing can substitute for watching
the arc and listening to the sound of the arc. A crisp, steady
sound, frequently referred to as a "Bacon frying sound""
should be heard. The actual frying sound can vary somewhat
and may have somewhat of a high pitch whine to it some-
where between the sound of a flying bee and a mosquito. If
these sounds are present, look at the arc to see if it is
steady, and producing low amounts of spatter. If large
MIG OPERATION AND THEORY
75
Basic Theory and Function
amounts of spatter are present, the puddle seems fluid
(appears wet) and the wire speed is within the targeted
range, decrease volts a little at a time to reduce the spatter.
If this does not correct the problem, change the torch angle
and torch height. Hold the torch more vertical, with less than
a 15 degree deviation from vertical and reduce stick-out of
wire to 3/8" or less. If this still does not help, reduce the
wire speed. Some spatter is normal, though it should be
minimal overall.
The wire can also pop and spatter if the voltage is too low for
the wire speed and/or wire diameter. This is mostly ob-
served as flying bits of red-hot but un-melted wire, along
with popping as the wire inconsistently stubs into the pud-
dle. This is followed by the wire pushing back against your
hand pressure while the wire visibly turns white/red hot
before burning off. Too low of voltage will also produce a
high piled bead with the toes (edges) of the weld not proper-
ly wetting in resulting in poor fusion.
Inductance
The third important variable in setting up the Lightning MTS
is the Inductance control. This third adjustment can greatly
vary the feel of the arc at any given volt and amp setting. It
is used to balance the stiffness of the arc against the wetness
of the arc. Some professionals refer to the "buttery-ness" of
the arc. " Buttery-ness" is arguably somewhat a subjective
term. However, it generally refers to how smooth and fluid
the arc feels and looks. In fact, the inductance alone can
affect how much wire speed or voltage is needed in any
given application. It does not typically require altering of the
Volts or the Wire Speed settings. However the inductance
control can expose poorly selected Volt/Wire Speed parame-
ters by magnifying the effects.
While Everlast uses the term "arc force" on some models as
well as inductance on others. The term is the same function
in MIG. It is also known in the industry by many different
terms. Often it is referred to as inductance, choke or slope.
Simply put, the Inductance adjustment controls how long it
takes the current to recover and rise to the established weld-
ing current to melt the wire after the wire contacts the puddle
and the current falls. This process is happening many times
a second so it isn't visible to the naked eye. But the overall
effect is visible as the wire burn off height is changed and a
change in the wetness of the puddle and how easily the
molten metal flows in toward the toes of the weld as it melts
off. If the unit has sufficient arc force, the edges of the weld
will easily wick into the puddle with little or no spatter with
little or no manipulation of the torch required. The pitch of
the arc will be medium. With too much inductance the pud-
dle may be uncontrollable and the arc will have a throaty,
raspy sound. Too little inductance and the puddle will be
narrow and possibly have a high ridge in the center. The
pitch will be very high and the puddle will seem sluggish and
less fluid.
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