The auxiliary gas used by the laser cutting machine to process different materials is different. The cutting thickness is different, and the pressure and requirements of the auxiliary gas are different. In terms of cost, cutting carbon steel with oxygen is relatively cheap, cutting carbon steel nitrogen amount is very large, the thicker the stainless steel nitrogen amount and purity are very high, the cost is relatively large.
Auxiliary gas of laser cutting machine is mainly used in:
1. Laser gas (the gas used to produce laser in the laser generator)
2. Compressed air (generally used to protect the light path, and some manufacturers are also used to do protective gas)
3. Auxiliary gas (gas sprayed from the cutting nozzle of the cutting machine)
Cutting carbon steel with oxygen, its purity requirements are generally 99.5% or higher. The main function is to help fire and blow off the cut slag. The pressure and flow rate of each laser cutting machine manufacturer are different, which is inseparable from the size of the cutting nozzle model and the thickness of the cutting material plate. Generally, the pressure is required to be 0.3-0.8Mpa, and the cutting nozzle is generally 0.02-0.05Mpa. Flow is not easy to say, such as cutting 22mm carbon steel, some manufacturers of flow to 10M3/h(including double-layer cutting nozzle protection with oxygen)
Nitrogen is used to cut stainless steel. The function is to prevent oxidation reaction and blow away the slag. The purity of nitrogen has high requirements (especially stainless steel above 8mm, the requirement is generally to achieve 99.999% purity) The pressure requirements are relatively large, generally require more than 1Mpa, such as to cut more than 12mm, or thicker to 25mm stainless steel, the required pressure is higher, more than 2Mpa or higher. The flow varies according to the model of the cutting nozzle, but it is very large, such as cutting 12mm stainless steel to some manufacturers to 150m3/h and cutting 3mm, as long as the flow below 50m3/h.
Laser welding machine will use a protective gas in the welding process, the protective gas is shot through the nozzle to reach the surface of the workpiece with a certain pressure, but many people do not know why to use the protective gas, the following by Shengyujia gas technicians to explain why the laser welding machine to use the protective gas:
Reason 1: Can protect the focusing lens from metal vapor pollution and liquid droplets sputtering
The protective gas can protect the laser welding machine focusing lens from metal vapor pollution and liquid droplet sputtering, especially in high-power welding, because its ejecta becomes very powerful, at this time to protect the lens is more necessary.
Reason 2: The protective gas is very effective in dispersing the plasma shielding generated by high power laser welding
The metal vapor absorbs the laser beam to ionize into a plasma cloud, and the protective gas around the metal vapor is also ionized by heat. If too much plasma is present, the laser beam is to some extent consumed by the plasma. As the second energy, plasma exists on the working surface, which makes the welding depth shallower and the welding pool surface wider. The recombination rate of electrons is increased by increasing the three-body collisions of electrons with ions and neutral atoms to reduce the electron density in the plasma. The lighter the neutral atom, the higher the collision frequency and the higher the recombination rate. On the other hand, only protective gases with high ionization energy do not increase the electron density due to the ionization of the gas itself.
Reason 3: The protective gas can prevent the workpiece from oxidation during the welding process
The laser welding machine must use a gas for protection, and the program should be set to the first protective gas and then the laser, to prevent the phenomenon of oxidation of the pulse laser during continuous processing. The inert gas can protect the molten pool, when some materials welding does not care about surface oxidation, it can not consider protection, but for most applications, helium, argon, nitrogen and other gases are often used to protect the workpiece from oxidation during the welding process.
These are the reasons why protective gases are used when laser welding machines are welding. Helium is generally used as a protective gas, which can inhibit the plasma to the greatest extent, thus increasing the penetration depth and improving the welding speed. And light weight can escape, not easy to cause porosity. Of course, from our actual welding effect, the effect of argon protection is also good.
Post time: Jan-08-2025