How to choose auxiliary gas for laser cutting machine?

The laser cutting machine needs to be equipped with auxiliary gases during use, mainly oxygen, nitrogen and air. When processing the workpiece, the optical fiber laser cutting machine will be irradiated by the laser focal spot, and the irradiated area will be melted and vaporized instantaneously. Then, the CNC equipment system will move the spot irradiation position to achieve automatic cutting.

1. Compressed air.

Air is suitable for cutting aluminum plate and galvanized steel plate. To some extent, it can reduce oxide film and save cost. It is generally used when the cutting plate is not relatively thick and the requirements for the cutting end face are not too high.

2. Nitrogen.

Nitrogen is an inert gas, which can prevent oxidation of the cutting end face of the product and combustion (which is easy to occur when the sheet is thick). Products with high requirements on the cutting end face and exposed outside without treatment can choose nitrogen.

3. Oxygen.

Oxygen mainly plays a combustion supporting role, which can make the cutting speed faster and the cutting thickness thicker. Oxygen is suitable for thick plate cutting, high-speed cutting and thin plate cutting. For example, oxygen can be used for some large carbon steel plates and some thick carbon steel plate structural parts.

Increasing the gas pressure can increase the cutting speed, but after reaching a set value, increasing the gas pressure will cause the cutting speed to decrease. Under the high auxiliary gas pressure, the reason for the decrease of cutting speed can be attributed to the enhancement of the cooling effect of the high gas flow velocity and the hanging action area, and also to the interference of the intermittent shock wave in the gas flow to the cooling of the laser action area.

The uneven pressure and temperature in the air flow will cause the density of the air flow field to change. Such a density gradient leads to the change of the refractive index in the field, which interferes with the focusing of the beam energy, resulting in refocusing or beam divergence. This kind of interference will affect the melting efficiency, and sometimes may change the mode structure, resulting in a decline in cutting quality. If the beam divergence is too large. Make the spot too large, and even cause the serious consequences of not being able to cut effectively.

Application of auxiliary gas:

1. Compressed air: it is widely used in the processing of some sheet metal cases, cabinets and cabinets.

2. Nitrogen: processing some decorative industries, aerospace and other parts;

The laser cutting machine cuts different materials with different auxiliary gases. The pressure and required flow rate of the auxiliary gas vary with the thickness of the cutting material.