Miller Electric CST 250 - Manuel (Page 25)

OM-212 817 Page 21
4-3. Stick Start Procedure − Scratch Start Technique
With Stick selected, start arc as
follows:
1
Electrode
2 Workpiece
3 Arc
Drag electrode across workpiece like
striking a match; lift electrode slightly
after touching work. If arc goes out
electrode was lifted to high. If
electrode sticks to workpiece, use a
quick twist to free it.
Normal open-circuit voltage is not
present before electrode touches
workpiece; only a low sensing voltage
is present between electrode and
workpiece. This allows electrode to
touch workpiece without overheating,
sticking, or getting contaminated.
1
2
3
4-4. Lift-Arc ™ Start Procedure
Lift-Arc Start
With Lift-Arct selected, start arc
as follows:
1
TIG Electrode
2 Workpiece
Turn gas on. Touch tungsten
electrode to workpiece at weld start
point. Hold electrode to
workpiece for 1-2 seconds, and
slowly lift electrode. Arc is formed
when electrode is lifted.
Normal open-circuit voltage is not
present before tungsten electrode
touches workpiece; only a low
sensing voltage is present between
electrode and workpiece. The
solid-state output contactor does
not energize until after electrode is
touching workpiece. This allows
electrode to touch workpiece
without overheating, sticking, or
getting contaminated.
Application:
Lift-Arc is used for the DCEN
GTAW process when HF Start
method is not permitted, or to
replace the scratch method.
1
1 − 2
Seconds
“Touch”
Do NOT Strike Like A Match!
2
Lift-Arc Start Method