Special Welding Processes - Lincoln Electric POWER MIG 262MP Operator's Manual

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POWER MIG 262MP

SPECIAL WELDING PROCESSES

PULSE WELDING
The pulsed-arc process is a spray transfer process wherein spray
transfer occurs in pulses at regularly spaced intervals. In the time
between pulses, the welding current is reduced and no metal
transfer occurs.
Pulsed-arc transfer is obtained by operating a power source
between low and high current levels. The high current level or
"pulse" forces an electrode drop to the workpiece. The low current
level or "background" maintains the arc between pulses.
PULSED MIG
Pulsed MIG is accessible as a "GMAW Type" in GMAW guided
setups. Pulsed MIG is an advanced form of welding that takes the
best of all the other forms of transfer while minimizing or
eliminating their disadvantages. Unlike short circuit, pulsed MIG
does not create spatter or run the risk of cold lapping. The welding
positions in pulsed MIG are not limited as they are with globular or
spray and its wire use is definitely more efficient. Unlike the spray
arc process, pulsing offers controlled heat input that allows better
welding on thin materials, lower wire feed speeds and leads to
less distortion and improved overall quality and appearance. This is
especially important with stain- less, nickel and other alloys that
are sensitive to heat input.
In Pulse MIG mode, the Ultimarc parameter adjusts the background
current and frequency of the wave. It can be set from -10 to 10,
with zero being the default value. When Ultimarc is set above zero,
the frequency increases thus increasing the droplet transfer rate.
This results in a narrower bead with more penetration which is
typically referred to as "crisp" welding performance. Setting
Ultimarc below zero results in the opposite and provides a wider
bead with lower penetration, typically referred to as "soft" welding
performance.
FIGURE B.5
EACH PULSE DELIVERS ONE DROPLET OF WELD MATERIAL
FREQUENCY
PULSE TIG
Pulse in TIG mode (GTAW) automatically switches the current
between the set point current on the main welding screen and the
background current. This feature can be used to reduce heat input
and warping of parts. Low pulse frequencies can help with weld
consistency, whereas higher pulse frequencies can increase travel
speed and prevent burn through on holes, edges and thin
materials.
The frequency parameter adjusts the pulse frequency from 0-300
Hz. Pulse TIG is off when the frequency is set to zero. The
background parameter adjusts the background current between
15% and 85% of the current set point. Lower background settings
often require higher current set points. The pulse % on-time is
fixed at 50%.
SPRAY TRANSITION
CURRENT
B-8
OPERATION