How to choose auxiliary gas for laser cutting machine equipment?
The laser cutting machine needs to be equipped with auxiliary gas, mainly oxygen, nitrogen and air. When processing the workpiece, the fiber laser cutting machine will be irradiated by the laser focus spot, and the irradiated area will be melted and vaporized instantaneously, and then the spot irradiation position will be moved by the CNC equipment system to realize 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. Generally, it is used when the cutting plate is relatively thick, and the requirements on the cutting end face are not too high.
Nitrogen is an inert gas, which prevents oxidation of the cutting end of the product during cutting and prevents burning (it is easy to occur when the sheet is thick. Nitrogen can be selected for products that have higher requirements on the cutting end and are not required to be exposed outside.
Oxygen mainly plays a role in supporting combustion, it 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, some large carbon steel plates and some thick carbon steel plate structural parts can use oxygen.
Increasing the gas pressure can increase the cutting speed, but after reaching a set value, continuing to increase the gas pressure will cause the cutting speed to decrease. Under the high auxiliary gas pressure, the reason for the reduction in cutting speed can be attributed to the enhancement of the cooling effect of the high air flow rate and the effect area, and it may also be the interference of intermittent shock waves in the air flow to the cooling of the laser action area.
The uneven pressure and temperature in the airflow will cause the density of the airflow field to change. Such a density gradient causes the refractive index in the field to change, thereby focusing the beam energy, causing refocusing or beam divergence. This interference will affect the melting efficiency, and may sometimes change the mode structure, resulting in a decrease in cutting quality, if the beam diverges too much. Making the light spot too large may even cause serious consequences that the cutting cannot be performed effectively.
Application of auxiliary gas:
1. Compressed air: It is widely used in the processing of some sheet metal chassis, cabinets and other products.
2. Nitrogen: processing some decoration industry, aerospace and other parts;
Laser cutting machines use different auxiliary gases to cut different materials. The pressure of the auxiliary gas and the required flow rate vary with the thickness of the cutting material.
The data are for reference only