Lincoln Electric LN-25 SVM179-B Service Manual page 25

OPERATION
B-11 B-11
OPTIONAL PREFLOW, BURNBACK AND
POSTFLOW TIMER KIT (K2330-2)
The preflow, Burnback and Postflow Timer Kit gives
you control over the shielding gas at the beginning and
end of the weld and prepares the end of the wire for
the next arc start. Additional shielding gas protection
is often required when welding aluminum, stainless
steel or exotic alloys.
NOTE: When stitch welding, set the postflow time to
maximum for best results.
Preflow Timer
The preflow timer range is OFF to 10 seconds.
Preflow time is the time delay from when the trigger is
pulled to when the wire starts to feed and is energized.
Preflow is used purge the welding gun with shielding
gads and helps to maximize porosity at the start of the
weld.
Burnback Timer
The Burnback timer range is OFF to 0.25 seconds.
The burnback timer controls the additional amount of
time the power source output remains ON after the
wire drive has stopped feeding wire. Burnback adjust-
ment prevents the wire from sticking to the weld at the
end of a weld and helps to condition the wire for the
next weld.
To set the burnback time, adjust the knob to approxi-
mately 0.03 seconds and then decrease or increase
the time as desired.
Postflow Timer
The postflow timer range is OFF to 10 seconds.
Postflow is the time from when the power source out-
put turns OFF until the postflow timer expires. Use
postflow to protect the weld while the weld cools.
LN-25™ PRO