Tweco 1000 Cutting Systems - Manual (Page 22)

INSTALLATION 3-4 Manual 0-2710
5. Connect the inner shield leads with red wires and
ring terminals to the mounting stud on the bulk-
head panel.
6. Remove the nut and bolt mounted to the Remote
Arc Starter front panel. Connect the outer shield
leads with green/yellow wires and ring terminals
to the mounting stud on the inside of the front
panel. Secure the stud to the front panel with a
hex nut. Connect a customer-supplied external
ground wire to the stud, outside the front panel,
and secure with a hex nut.
7. Check the torch for proper parts assembly.
CAUTION
The torch parts (gas distributor, electrode, tip, and
shield cup) must correspond with plasma and sec-
ondary selection, output current level, and type of
operation (cutting or gouging). Refer to Section
4.04, Torch Parts Selection.
8. Connect the Torch Supply Leads components to
the Remote Arc Starter (see NOTE).
NOTE
Refer to the Power Supply Operating Manual 0-
2708 for details on making connections.
3.06 Gas Selection
CAUTIONS
Maximum input gas pressure must not exceed 125
psi (8.6 bar)
Air supply must be free of oil, moisture, and other
contaminants. Excessive oil and moisture may
cause double-arcing, rapid tip wear, or even com-
plete torch failure. Contaminants may cause poor
cutting performance and rapid electrode wear.
The type of operation will determine the best gases to be
used. Refer to the following and select the plasma and
secondary gases that best fit the operation(s):
A. Plasma Gases
NOTE
Refer to Section 2.03, Specifications & Design Fea-
tures, for proper gas pressure and flow rate.
1. Air Plasma
• Most often used on ferrous or carbon base materials
to obtain good quality at faster cutting speeds.
• Air plasma is normally used with air secondary.
• Only clean, dry air is recommended for use as plasma
gas. Any oil or moisture in the air supply will sub-
stantially reduce torch parts life.
• Provides satisfactory results on nonferrous materi-
als.
2. Nitrogen (N2) Plasma
• Provides better cut quality on nonferrous materials
such as stainless steel and aluminum.
• Can be used in place of air plasma with air second-
ary or carbon dioxide (CO
2
).
• Provides much better parts life than air.
• A good clean welding grade nitrogen should be used.
3. Argon/Hydrogen (Ar/H2) Plasma
• Recommended for use on 3/4 in (19 mm) and thicker
stainless steel. Recommended for 1/2 inch (12 mm)
and thicker nonferrous materials. Ar/H2 is not nor-
mally used for thinner nonferrous materials because
less expensive gases can achieve similar cut quality.
• Poor cut quality on ferrous materials.
• Provides faster cutting speeds and high cut quality
on thicker materials to offset the higher cost.
• A 65% argon / 35% hydrogen mixture should be
used.
4. Oxygen (O
2
) Plasma
• Oxygen is recommended for cutting ferrous materi-
als.
• Provides faster cutting speeds.
• Provides very smooth finishes and minimizes nitride
build-up on cut surface (nitride build-up can cause
difficulties in producing high quality welds if not
removed).