Everlast PowerMTS 251Si Operator's Manual page 41

Section 3
pulse wave. This provides lower than typi-
cal heat input, while still providing ade-
quate wet-in characteristics and a narrow-
er arc cone. As briefly touched on earlier,
the Everlast version of MIG pulse pulses
Voltage, instead of current. For discussion
purposes, the "MIG pulse Voltage" listed
on the machine panel is also called the
"peak" Voltage. The MIG pulse volts setting
is actually the high voltage point of the
MIG pulse cycle. The actual base Voltage
function itself is displayed as a percentage
of the peak Voltage and is the low point of
the MIG pulse cycle. The base Voltage
range of adjustment is from 10% to 99% of
welding Voltage. In general though, a
good starting point for the pulse base Volt-
age is around 70%. The goal of adjusting
the pulse Voltage is to positively influence
the "freezing" property of the weld puddle
without loosing too much fluidity. Raising
the pulse base Voltage value will increase
puddle fluidity and wet-in while lowering
the pulse base Voltage will generally tend
to make the puddle freeze much faster.
Keep in mind, these are the general effects
that you will notice if all other parameters
are kept the same during adjustment.
Setting the base Voltage percent correctly
also depends upon correctly setting the
peak Voltage correctly. Commonly recom-
mended welding voltages for standard MIG
welding do not often apply. Usually, a
higher peak pulse Voltage is used than is
used for non-pulse welding, for the same g
wire and metal thickness. This is needed
to maintain penetration and weld speed.
Even on thinner metals, an increase of 10-
30% over typical Peak Voltage is a recom-
mended starting point for setting the weld-
ing Voltage. On thicker metals, a greater
PULSE MIG OPERATION
Basic Theory and Function
increase over typical suggested peak Volts
may prove helpful. But at the very least,
consider 10-30% additional Volts (over the
standard recommended non pulse volts) as
go-to starting point when setting peak
Volts. After setting wire speed and peak
Voltage, set base Voltage to 70%. Fine tune
it by ranging up or down at increments of
5% at a time, while running test beads dur-
ing the adjustment process. If the weld
puddle is too fluid, try adjusting the pulse
base voltage first. If the setting is not
forming a good puddle or it seems sluggish
or the weld bead is piling up with poor
penetration/fusion with excessive spatter,
consider adjusting the peak Voltage up a
little more before going above 80% base
Voltage. This is because the freezing effect
begins to diminish as peak and base volt-
age gap narrows (when all other settings
remain unchanged). This is not to say the
on some occasions, a base Voltage setting
of greater than 80% may not prove useful.
However, in general, as the Voltage differ-
ential of the pulse is reduced, you'll find
that other settings may not have as much
effect when trying to fine tune the pulse
unless the rest of the pulse parameters are
adjusted to more extreme settings. But by
then, you may find the pulse is no longer
smooth or stable. On the first round of
adjustments, set the Peak Voltage and
Base Voltage once, and then proceed to
adjust pulse frequency and then to pulse
time-on. After that, return to fine tuning
the Peak and base voltage if needed.
2. Pulse Frequency (Hz). The frequency of the
pulse is defined as the number of pulse
cycles completed in one second. This is
sometimes referred to as PPS, or pulses
per second. When dealing with frequency
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