Nitrogen machine equipment in the plasma air cutting method to dry compressed air as a processing gas, mainly used for cutting carbon steel, can also be used to cut stainless steel and aluminum. Since the air is mainly composed of nitrogen and oxygen, when cutting carbon steel, the exothermic reaction of oxygen and iron in the incision provides additional heat, while generating FeO slag with low surface tension and good fluidity, improving the fluidity of molten metal in the incision, so not only the cutting speed is faster, but also the cutting surface is smooth and clean, the lower edge of the incision is basically non-stick slag, and the cutting surface is small. When cutting stainless steel and aluminum, oxygen reacts with chromium and aluminum in stainless steel, and the cutting surface is rough, and this processing method is generally not used when the quality of the cutting surface is high.

Plasma air cutting method mainly has the following disadvantages:

(1) nitriding layer is attached to the cutting surface, and pores will be generated in the weld during welding, so the cutting edge for welding needs to be polished with a grinding wheel to remove the nitriding layer. (2) Due to the existence of oxidation, the electrode and nozzle are easy to lose, and the service life is short. Plasma nitrogen water vortex cutting method uses nitrogen as the working gas, which is mainly used for cutting stainless steel and aluminum. The working gas forms a vortex flow through the vortex ring, so that the plasma current also shoots towards the workpiece in a vortex way, so that a cutting edge with a very small Angle can be obtained. Around the working gas, there is a treated high-pressure water flow, which greatly increases the energy density of the arc and forms a plasma arc with high temperature, good stiffness and high flow rate. In addition, part of the water dissociates into hydrogen and oxygen, which also has a certain promotion effect on the cutting process.

Compared with other plasma cutting methods, the plasma nitrogen water vortex cutting method has the following characteristics:

(1) Fast cutting speed;

(2) Good cutting quality. The incision width is small, the cutting surface is smooth, the bevel Angle is small, and the lower edge of the incision is not sticky

(3) Cutting deformation is small, high precision;

(4) Long nozzle life;

(5) Suitable for underwater processing, basically no smoke and arc light, low noise.