Auxiliary gas can help the laser beam to cut the workpiece better and blow away the slag quickly, which also plays an important role in improving the quality of laser cutting. 

The type of gas and the pressure have an effect on edge roughness and burr formation. The gases commonly used for laser cutting are oxygen, nitrogen and air, and different auxiliary gases have different effects.

1 Cutting with air: Cutting with air is the most cost-effective method, but burrs may appear on the metal cutting surface, which become more and more obvious as the thickness of the sheet increases.

 In addition, the metal cutting surface turns black and the quality of the workpiece is poor. To achieve a higher cutting quality with air cutting, a high-performance laser cutting machine must be selected. 

For example, a 12000W laser cutting machine that uses air to cut carbon steel below 10mm still has good cutting quality. To ensure the cutting quality and prevent damage to the laser generator during air cutting, the compressed air must be pure and constant

2Cutting with oxygen: 

Oxygen is often used to cut thick carbon steel because the iron element reacts chemically with oxygen, causing the metal to absorb heat, promoting the melting of the metal and improving the cutting ability. 

However, cutting with oxygen increases the risk of material oxidation. Generally, oxygen is used for carbon steel plate cutting, low pressure punching and low pressure cutting.

3 Cut nitrogen: When nitrogen is used as the auxiliary gas of the metal laser cutting machine, the nitrogen forms a protective atmosphere around the molten metal to prevent the material from being oxidized, thus ensuring the quality of the workpiece. 

In general, nitrogen is used to cut stainless steel, galvanized sheet metal, aluminum, aluminum alloys, brass and other materials by low-pressure perforation and high-pressure cutting. 

When cutting with nitrogen, the change of gas flow has a great influence on the cutting performance. In order to achieve a good cutting quality, the gas flow should be sufficient and constant.

4 Control of the auxiliary gas The pressure of the auxiliary gas affects the slag bubble effect and therefore the final quality of the laser cutting. Different metal materials require different optimum gas pressures. 

If the gas pressure is too low, the molten material cannot be blasted off in time and sticks to the back of the cutting edge. If the gas pressure is too high, the cutting ability of the laser beam is weakened and the cut seam becomes larger and rougher. Therefore, different gas pressures must be set when cutting different materials in order to achieve better laser cutting effects.