In laser cutting process of metal materials, nitrogen cutting is being adopted by more and more manufacturers. Here are the selection of cutting auxiliary gas by different materials.
1) Carbon steel
Carbon steel is often cut with oxygen. Oxygen participates in the combustion during oxygen cutting, and the melting position is close to the boiling point. High temperature causes strong reaction, which could not ensure smooth cross section. In addition, the oxidation reaction and the increased heat affected zone make the cutting quality relatively poor, and the quality defects such as slit width, cross-section twill, surface roughness and weld slag are prone to occur.
In nitrogen cutting, the material is completely melted by laser energy, and the nitrogen blows out the slit and avoids unsuitable chemical reactions. The temperature in the melting point region is relatively low, and thanks for the cooling and protection of nitrogen gas, the reaction is stable and uniform, so the cutting quality is high. The section is fine and smooth, surface roughness is low, and there is no oxide layer
2) Stainless steel
From cost considerations, for stainless steel material with oxidized cutting edge acceptable better uses oxygen cutting. However, as the content of alloying elements such as Ni in stainless steel is large, the viscosity of the melt material is big, and the fluidity is poor. The lower air pressure during oxygen cutting tends to cause quality defects such as slag.
For applications require high-quality non-oxidized section of cut edge, nitrogen cutting meets the high requirements.
3) Aluminum, brass
Aluminum and brass have high reflectivity and low absorption rate for lasers, requiring high power to melt the material. Moreover, it requires reflection absorbing device to prevent the uneven linear wave from being reflected back to the lens to protect the safety of the laser. For this application, nitrogen cutting is required.
Aluminum has low melting point and can be cut with oxygen if material thickness is below 3 mm, but the quality is poor, it will have burrs. When use nitrogen to cut, the cutting section is smooth.