Tweco Max 300 w-Merlin 6000GST - Manual (Page 22)

INSTALLATION 3-4 Manual 0-2642
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 qual-
ity.
• Poor cut quality on ferrous materials (carbon steel).
• 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 mate-
rials (carbon steel).
• Provides faster cutting speeds.
• Provides very smooth finishes and minimizes ni-
tride build-up on cut surface (nitride build-up can
cause difficulties in producing high quality welds
if not removed).
B. Secondary Gases
NOTE
Refer to Appendix 2, Cutting Speed Charts, for
proper gas pressure and flow rates.
1. Compressed Air Secondary
• Air secondary is normally used when operating
with air plasma and occasionally with nitrogen
plasma.
• Improves cut quality on some ferrous materials.
• Inexpensive - reduces operating costs.
2. Carbon Dioxide (CO
2
) Secondary
• CO
2
secondary is used with nitrogen or Ar/H2
plasma.
• Provides good cooling and maximizes torch parts
life.
• Provides good cut quality on ferrous or nonferrous
material.
• May reduce smoke when used with Ar/H2 plasma.
NOTE
When CO
2
is used as the secondary gas, twenty
(50 lb) cylinders must be manifolded together or a
bulk CO
2
system used to get the required flow rate
of 220 scfh. Shop compressed air is a good alterna-
tive if providing the required CO
2
flow rate is not
feasible.
3. Nitrogen (N2) Secondary
• Nitrogen secondary is used with Ar/H2 plasma.
• Provides smooth finishes on nonferrous materials.
• May be used with nitrogen plasma in order to oper-
ate from one compressed gas cylinder - but torch
parts life may be shorter than with CO
2
secondary.
• May reduce smoke when used with Ar/H2 plasma.
4. Water Secondary
• Water secondary should be used only in mechanized
applications - never in hand cutting!
• Normally used with nitrogen, Ar/H2, or air plasma.
• Provides very smooth cut surface.
• Reduces smoke and heat input to the workpiece.
• Effective up to 1 inch maximum material thickness.
• Tap water provides low operating expense.
3.07 Gas Connection
A. Connection
Connect the gases to the Power Supply as de-
scribed in the Master Power Supply Operating
Manual (0-2652) supplied with the Power Supply.
CAUTION
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.
B. Checking Air Quality
To test the quality of air, place a welding filter lens in
front of the torch and turn on the gas. Any oil or
moisture in the air will be visible on the lens. Do not
initiate an arc!
C. Filtering
An inline pneumatic dryer/evaporator type air fil-
ter, capable of filtering to at least 5 microns, is required
when using air from a compressor. This type filter
will insure that moisture, oil, dirt, chips, rust particles,
and other contaminants from the supply hose do not
enter the torch. For highly automated applications,
a refrigerated drier may be used.
NOTE
Do not use an air line filter with high pressure gas
cylinders.