Tweco 300 XT Auto-Cut 400V - Manual (Page 53)

AUTO-CUT 300 XT
Manual 0-5290 OPERATION 4-5
3. Use care in handling torch leads and protect them from damage.
4. When using water as the shield note the following:
• Use clean drinking quality tap water to help prevent particulate build-up within the system water shield
plumbing.
• Particulate contamination and build-up can cause reduced consumable parts life and premature torch failure.
• A cartridge type particulate water filter may help achieve optimum cutting performance.
4.04 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
substantially reduce torch parts life.
• Provides satisfactory results on nonferrous 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 (O2) Plasma
• Oxygen is recommended for cutting ferrous materials.
• Provides faster cutting speeds.
• Provides very smooth finishes and minimizes nitride buildup on cut surface (nitride buildup can cause
difficulties in producing high quality welds if not removed).
4. 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 shield.
• A good clean welding grade nitrogen should be used.
B. Shield Gases
1. Compressed Air Shield
• Air shield is normally used when operating with air or oxygen plasma.
• Improves cut quality on some ferrous materials.
• Inexpensive - reduces operating costs.
2. Nitrogen (N2) Shield
• Nitrogen shield is used with nitrogen (N2) or Ar/H2 (H35) plasma.
• Provides smooth finishes on nonferrous materials.
• May reduce smoke when used with Ar/H2 plasma.
3. Water Shield