63. 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,
-
- stainless steel
-
- monel
-
- super-alloy plates
· 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.
· Advantages
-
- 3 to 5 times faster than conventional gas cutting
-
- can deal with any conducting material, including those not suited to normal gas cutting.
-
- stainless steels
-
- chromium-nickel alloys
-
- aluminum
-
- copper
-
- etc
-
- 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
-
- medium - plasma
-
- tool - plasma jet
-
- maximum temperature = 16,000C
-
- maximum velocity of plasma jet = 500 m/sec
-
- maximum mrr = 150 cm3/min
-
- specific energy = 1000 W/cm3/min
-
- power range = 2 to 200 KW
-
- maximum plate thickness = 200 mm (depends on material)
-
- cutting speed = 0.1 to 7.5 m/min
-
- voltage 30 to 250 V
-
- current <= 600 A
-
- critical parameters - voltage, current, electrode gap, gas flow rate, nozzle dimensions, melting temperature
-
- materials applications - all conducting materials
-
- shape application - cutting plates
-
- limitation - low accuracy
