Lincoln Electric PIPEFAB Series Operator's Manual page 85

PIPEFAB™ WELDING SYSTEM
Example 2: 4-Step Trigger: Manual Control of Start and Crater �mes with Burnback ON.
The 4-Step trigger sequence gives the most flexibility when the Start, Crater and Burnback func�ons are
ac�ve. This is a popular choice when welding aluminum because extra heat may be needed during Start
and less heat desired during crater. With 4-Step trigger, the welder chooses the amount of �me to weld
at the Start, Weld and Crater se�ngs by using the gun trigger. Burnback reduces the occurrence of wire
to s�cking into the weld pool at the end of a weld and condi�ons the end of the wire for the next arc
start.
In this sequence,
PREFLOW: Shielding gas begins to flow immediately when the gun trigger is pulled.
RUN-IN: A�er preflow �me expires, the power source regulates to the start output and wire is
advanced towards the work piece at the run-in WFS. If an arc is not established within
2.0 seconds, the power source output and wire feed speed skips to the weld se�ngs.
START: The power source welds at the start WFS and voltage un�l the trigger is released.
UPSLOPE: During upslope, the power source output and the wire feed speed ramp to the weld
se�ngs throughout the start �me. The �me period of ramping from the start se�ngs
to the weld se�ngs is called UPSLOPE. If the trigger is pulled before upslope is
complete, WELD is skipped and the sequence jumps to DOWNSLOPE.
WELD: A�er upslope, the power source output and the wire feed speed con�nue at the weld
se�ngs.
DOWNSLOPE: As soon as the trigger is pulled, the wire feed speed and power source output ramp to
the crater se�ngs throughout the crater �me. The �me period of ramping from the
weld se�ngs to the crater se�ngs is called DOWNSLOPE.
CRATER: During CRATER, the power source con�nues to supply output at the crater WFS and
voltage.
BURNBACK: When the trigger is released, the wire feed speed is turned OFF and the machine output
con�nues for the burnback �me.
POSTFLOW: Next, the machine output is turned OFF and shielding gas con�nues un�l the post flow
�mer expires.
FIGURE B.28
B-34
OPERATION