Tweco 300 Ultra-Cut(March 2013) - Manual (Page 84)

OPERATION 4-14 Manual No. 0-5134
ULTRA-CUT 300
4.10 Gas Selection
A. Plasma Gases
1. Air Plasma
• Most often used on ferrous or carbon base materials for good quality at faster cutting speeds.
• Air plasma is normally used with air shield.
• Only clean, dry air is recommended for use as plasma gas. Any oil or moisture in the air supply will substan-
tially reduce torch parts life.
• Provides satisfactory results on nonferrous materials and reduced weldability on ferrous materials.
2. Argon/Hydrogen (H35) 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 normally 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.
3. Oxygen (O
2
) Plasma
• Oxygen is recommended for cutting ferrous materials.
• 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).
4. Nitrogen (N
2
) Plasma
• Provides better cut quality on nonferrous materials such as stainless steel and aluminum.
• Can be used in place of air plasma with air shield or carbon dioxide (CO
2
).
• Provides much better parts life than air.
• A good clean welding grade nitrogen should be used.
5. H17 Plasma (17.5% Hydrogen / 32.5% Argon / 50% Nitrogen)
• Recommended for 1/2 inch (12 mm) and thicker nonferrous materials. H17 is not normally used for thinner
nonferrous materials because less expensive gases can achieve similar cut quality.
• Alternative to H35 Plasma. Yields slightly higher cut speeds and similar cut quality.
• When using H17, the gas should be supplied to the gas supply port marked “H35”.
• Poor cut quality on ferrous materials.
6. Marking Gas
•Argon is required for Marking.