Scratch Start Tig; Lift-Arc Start Procedures - Miller Electric STR 350C Owner's Manual

4-8. Scratch Start TIG

4-9. Lift-Arc Start Procedures

Lift-Arc Start Method
OM-249 914 Page 22
1
1 − 2
"Touch"
Seconds
Do NOT Strike Like A Match!
2
This starting method is not accept-
able for critical applications since
small tungsten particles may be-
come embedded in the workpiece
and contaminate the weld.
Turn gas on.
Quickly 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
workpiece, use a quick twist to free
it.
Ref. WM Marketing
Lift-Arc Start
When Lift-Arct button light is On,
start arc as follows:
1 TIG Electrode
2 Workpiece
Touch tungsten electrode to work-
piece at weld start point, enable out-
put and shielding gas with torch trig-
ger, foot control, or hand control.
Hold electrode to workpiece for
1-2 seconds, and slowly lift elec-
trode. 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 with-
out overheating, sticking, or getting
contaminated.
Application:
Lift-Arc is used for the DCEN or AC
GTAW process when HF Start
method is not permitted, or to re-
place the scratch method.
to