Tweco 200 Ultra-Cut - Manual (Page 76)

Manual No. 0-5056 Ultra-Cut 200 4-10 OPERATION
4.06 Gas Selection
A. Plasma Gases
• 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.
• 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.
• 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).
• 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.
B. Shield Gases
• Air shield is normally used when operating with air plasma.
• Improves cut quality on some ferrous materials.
• Inexpensive - reduces operating costs.
• Nitrogen shield is used with Ar/H2 (H35) plasma.
• Provides smooth finishes on nonferrous materials.
• May reduce smoke when used with Ar/H2 plasma.
• Water shield 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 1/2 inch (12.7 mm) maximum material thickness.
• Tap water provides low operating expense.