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Laser cutting gas applications

The auxiliary gases used by laser cutting machines to process different materials are different. The pressure and requirement of auxiliary gas are different with different cutting thickness. From the cost, cutting carbon steel with oxygen is relatively cheap, cutting carbon steel nitrogen consumption is very large, thicker stainless steel nitrogen consumption and purity requirements are very high, the cost is relatively large.

The auxiliary gas of laser cutting machine is mainly used in:

     1. Laser gas (gas used to generate laser in laser generator)

     2. Compressed air (generally used to protect the optical path, and some manufacturers also use it as a protective gas)

     3, auxiliary gas (gas from the cutting machine nozzle)

Laser cutting gas

Oxygen for cutting carbon steel is generally required to be 99.5% pure or higher. The main function is to fuel and blow off the cut slag. The pressure and flow of each laser cutting machine manufacturer is different, which is closely related to the size of the cutting nozzle and the thickness of the cutting material. Generally, the required pressure is 0.3-0.8mpa, and the cutting nozzle is 0.02-0.05mpa. The flow rate is not easy to say, such as cutting 22mm carbon steel, the flow rate of some manufacturers to reach 10M3/h(including the oxygen for the protection of double-layer cutting nozzle)

Nitrogen is used in cutting stainless steel. The function is to prevent oxidation and blow off slag. Nitrogen purity has high requirements (especially 8mm above the stainless steel, the requirements generally to achieve 99.999% purity) pressure requirements, the general requirements of more than 1Mpa, such as to cut more than 12mm, or thicker to 25mm stainless steel, the requirements of higher pressure, more than 2Mpa or higher. Flow varies according to the model of the cutting nozzle, but it is very big, such as cutting 12mm stainless steel to some manufacturers to 150m3/h and cutting 3mm, as long as 50m3/h below the flow.

Laser welding machine in welding process are used to a protective gas, gas through the nozzle mouth protection with certain pressure injection reach the surface of the workpiece, but many people don't know why want to use protective gas, the gas by st. Martin, technical personnel for you explain why want to use when the laser welding machine for welding protective gas:

Laser cutting industry

Reason 1: 

It protects the focusing lens from metal vapor contamination and sputtering of liquid droplets

Shielding gas can protect the laser welder focusing lens from metal vapor contamination and sputtering of liquid droplet, especially in high power welding, where the protective lens is necessary because the ejector becomes very powerful.

Reason 2: 

The shielding gas is very effective in dispersing the plasma shielding produced by high-power laser welding

The metal vapor absorption laser beam is ionized into a plasma cloud, and the protective gas around the metal vapor is ionized by heat. If there is too much plasma, the laser beam is somehow consumed by the plasma. As the second kind of energy, plasma exists on the working surface, which makes the depth of weld pool shallower and the surface of weld pool wider. The electron recombination rate is increased by increasing electron collisions 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 a protective gas with a high ionization energy does not increase the electron density by ionization of the gas itself.

Reason 3: 

Protective gas can prevent the workpiece from oxidation during the welding process

The laser welding machine must be protected by a kind of gas, and the program should be set to first emit protective gas and then emit laser, so as to prevent oxidation of pulse laser during continuous processing. And inert gas can protect the molten pool, when some materials welding do not care about surface oxidation may not consider protection, but for most applications often use helium, argon, nitrogen and other gases as protection, so that the workpiece in the welding process from oxidation.

The above is why the laser welding machine welding to use protective gas reason. Helium is generally used as protective gas to suppress the plasma to the greatest extent, thus increasing the depth of fusion and welding speed. And light can escape, not easy to cause pores. Of course, from our actual welding results, the protection effect with argon is also good.

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