Lincoln Electric IDEALARC SP-255 Service Manual page 32

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USING THE 4-STEP INTERLOCK FUNCTION IN
AUTO MODE
When the 4-Step Interlock function is not activated, the
trigger functions in the normal mode so that welding
happens only when the trigger is closed.
When the 4-Step Interlock function is activated, it
functions as follows:
When the arc is struck, the gun trigger may be released.
The welding continues until welding is stopped by either
of these two methods:
1) The arc is extinguished by manually jerking the gun
away from the work.
2) The gun trigger is closed and then released at the
end of the weld. This action returns the trigger func-
tion to the normal mode so the weld stops when the
trigger is released. Releasing the trigger reinstates
the trigger interlock function for the next weld. This
is the preferred Interlock mode because it provides
better control at the end of the weld and allows au-
tomatic burnback to prevent excessive wire feed
speed overrun.
The 4-step trigger feature does not function when using
SPOT or STITCH timed welding modes.
MAKING A SPOT WELD IN AUTO MODE
Arc spot plug welds are used when continuous welds
are not needed or to hold thin sheet metal together prior
to stitch welding or continuous welding. Arc spot plug
welds are made by using a punch to make a 3/16 inch
(5 mm) diameter hole in the top sheet and arc welding
through the hole into the back sheet.
To make an arc spot plug weld
1. Punch 3/16" (5 mm) hole in top sheet.
2. Set the procedure for the metal thickness to be
welded.
3. Press the SPOT key. SPOT : ON is displayed.
4. Press the CENTER UP & DOWN ARROW keys to
set the required Spot On time. Suggested initial
setting is 1.2 seconds.
5. Press the SPOT key.
screen. Spot timer status is shown in bottom left
corner of screen.
6. Install spot weld nozzle (if available) on gun.
OPERATION
Display returns to Auto
IDEALARC
7. Press spot weld nozzle against the top sheet so the
top and bottom sheets are tight together. If a spot
weld nozzle is not used, smoother welds will result
by moving the welding wire in a small circle while
making the weld.
8. Close the trigger and hold it closed until the arc
goes out.
SP-255
®
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