Lincoln Electric Power Feed 25M Operator's Manual page 55

POWER FEED™ 25M
EXAMPLE 3 - 2 STEP TRIGGER: Customized Arc Start, Crater
and Arc End. Sometimes it is advantageous to set specific arc
start, crater and arc ending parameters for the ideal weld. Many
times when welding aluminum crater control is necessary to
make a good weld. This is done by setting Start, Crater and
Burnback functions to desired values. (See Figure B.21)
For this sequence,
PREFLOW:
Shielding gas begins to flow immediately when the gun trigger is
pulled.
RUN-IN:
After preflow time 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 1.5 seconds, the
power source output and wire feed speed skips to the weld set-
tings.
START & UPSLOPE:
As soon as the trigger is released, the wire feed speed and
power source output ramp to the crater settings throughout the
crater time. The time period of ramping from the weld settings
to the crater settings is called DOWNSLOPE.
WELD:
After upslope, the power source output and the wire feed speed
continue at the weld settings.
CRATER:
As soon as the trigger is released, the wire feed speed and
power source output ramp to the crater settings throughout the
crater time. The time period of ramping from the weld settings to
the crater settings is called DOWNSLOPE.
CRATER & DOWNSLOPE:
As soon as the trigger is released, the wire feed speed and
power source output ramp to the crater settings throughout the
crater time. The time period of ramping from the weld settings
to the crater settings is called DOWNSLOPE.
BURNBACK:
After the crater time expires, the wire feed speed is turned OFF
and the machine output continues for the burnback time.
POSTFLOW:
Next, the machine output is turned OFF and shielding gas contin-
ues until the post flow timer expires.
FIGURE B.21
B-39
OPERATION