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Talking about the Assistant Gas of Laser Cutting Machine
- Mar 31, 2018 -

Laser cutting machines use different auxiliary gases for cutting different materials. The difference in the thickness of the cutting material, the auxiliary gas pressure and the required flow rate are not the same. The gas pressure of the assist gas has a direct effect on the result of the laser cutting.

The laser working gas is used to generate laser light; the protective gas is used to protect the optical device and drive the shutter. The working gas of the laser is mixed with helium, nitrogen, and carbon dioxide gas in a certain proportion. This proportion is predetermined at the factory to ensure the best performance. The auxiliary gas not only blows away the slag in time, but also cools the workpiece and cleans the lens. The use of different auxiliary gases can change the cutting speed and the quality of the kerf surface, which is of great significance for the cutting of special metals.

The auxiliary gas types are oxygen, air, nitrogen, and argon. Air nitrogen is used as a protective gas when cutting to prevent oxidation film from occurring; argon is used for titanium metal cutting.

1, compressed air.

The air is suitable for the cutting of aluminum plates, non-metals and galvanized steel plates, to a certain extent it can reduce the oxide film and save costs. It is generally used when the cutting board is not relatively thick and the cutting end surface requirements are not too high. There are many applications in the product industries such as some sheet metal chassis cabinets.

2, nitrogen.

Nitrogen is an inert gas, which prevents oxidation of the cut surface of the product during cutting, and prevents combustion (which occurs easily when the material is thicker. Nitrogen is required for products with high requirements for cutting and exposed surfaces. For example, some decorative industries, aviation Aerospace and other special parts;

3, oxygen.

Oxygen mainly serves as a combustion-supporting effect, which can make the speed faster and the thickness of the cut thicker when cutting. Oxygen is suitable for thick plate cutting, high speed cutting and very thin plate cutting. For example, some larger carbon steel plates and some thick carbon steel structural parts can use oxygen.

Increasing the gas pressure can increase the cutting speed, but after reaching a maximum value, increasing the gas pressure will cause the cutting speed to decrease. Under high auxiliary gas pressures, the reason for the lower cutting speed can be attributed not only to the increase in the airflow velocity pair and the cooling effect of the hanging zone, but also to the interference of the intermittent shock wave in the gas flow to the cooling of the laser application zone. Uneven pressures and temperatures in the air flow can cause changes in the airflow field density. Such a density gradient results in a change in the refractive index within the field, thereby converging the focus of the beam energy, causing refocusing or beam divergence. This interference can affect the melting efficiency, and sometimes it can change the mode structure, resulting in a decline in the quality of the cut if the beam diverges too much. Making the spot too large may even result in serious consequences of inefficient cutting.