In addition to the general form, plasma cutting method also comes from water compression plasma cutting. The most commonly used methods are ordinary plasma cutting and air plasma cutting.
1, general cutting
Generally, plasma cutting does not use protective gas, and working gas and cutting gas are ejected from the same nozzle. When the arc is started, a small stream of ionic gas is ejected as ionization medium; When cutting, a large amount of airflow gas is ejected at the same time to eliminate molten metal.
2. Air cutting
Air plasma cutting generally uses compressed air as ion gas, which has low cutting cost and convenient gas source. The compressed air is decomposed and ionized by heating in the arc, and the generated oxygen cuts the metal to produce a chemical exothermic reaction, which accelerates the cutting speed. The enthalpy of fully ionized air plasma is high, so the arc energy is large and the cutting speed is fast.
Various plasma arc cutting process parameters directly affect the stability, cutting quality and effect of the cutting process. The main cutting specifications are briefly described as follows.
No-load voltage and arc column voltage:
The plasma cutting power supply must have a high enough no-load voltage to easily ignite the arc and make the plasma arc burn stably. The no-load voltage is generally 120-600V, and the arc column voltage is generally half of the no-load voltage.
Increasing the voltage of arc column can obviously improve the power of plasma arc, so it can improve the cutting speed and cut metal plates with greater thickness. Arc column voltage is often realized by adjusting gas flow and increasing internal contraction of electrode, but the arc column voltage cannot exceed 65% of no-load voltage, otherwise the plasma arc will be unstable.