1. AIR-PLASMA CUTTING
• Basic process - uses an ionized gas jet (plasma) to cut material
• can be used on all materials that conduct electricity
• can be used to cut materials resistant to oxy-fuel cutting,
• Plasma is generated by exposing a gas stream to the electrons from an electric arc. High velocity electrons generated by the arc impact gas molecules, and ionize them.
• The gas is forced through the nozzle, and the jet heats the metal, and blasts the molten metal away.
- 3 to 5 times faster than conventional gas cutting
- can deal with any conducting material, including those not suited to normal gas cutting.
- works best on ranges from .03” to 1”
- More efficient than other types of gas plasma
- can cut up to .15 m/sec continuously.
• Summary of Air-Plasma characteristics,
- mechanics of material removal - melting
- maximum temperature = 16,000C
- maximum velocity of plasma jet = 500 m/sec
- specific energy = 1000 W/cm3/min
- maximum plate thickness = 200 mm (depends on material)
- cutting speed = 0.1 to 7.5 m/min
- critical parameters - voltage, current, electrode gap, gas flow rate, nozzle dimensions, melting temperature
- materials applications - all conducting materials
- shape application - cutting plates
1.2 PRACTICE PROBLEMS