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Various types of lasers are used for metal cutting. Carbon dioxide (CO2) lasers are generally used to cut flat metal surfaces. YAG lasers are ideal for 3D applications as they can be operated across flexible fiber optic cables and manipulated with a robot. But there are no hard and set rules. CO2 lasers offer a high beam quality at high beam power, which is advantageous for cutting thick materials. Nd:YAG lasers cannot match CO2 lasers when it comes to beam quality at high powers, but this may soon change as Disk lasers (Yt:YAG) evolve. Another area enjoying growing interest is Fiber lasers. They also enable the beam to be delivered along fiber optic cables.
Advantages of laser cutting are the cut precision and the cutting speeds to be achieved, but also potential for automation allowing to run a laser machine unattended in night shifts.
Oxygen or nitrogen are the principal gases used in laser cutting, argon is applied on sensitive materials such as titanium that would react with either oxygen or nitrogen. Steel is annealed to ignition temperature with a laser beam and an oxygen gas jet burns the material similar to oxy-fuel cutting and blows out melt and slag. Oxygen adds thermal energy to the process accelerating the cutting speed, but leaves an oxide layer on the cut surfaces. The higher the oxygen purity the higher the cutting speed.
Nitrogen is used to achieve metallic cut surfaces so called “clean cuts”. These are required in case of stainless steel to preserve corrosion resistance or if the cut parts are to be powder coated after cutting. The powder will not stick on the oxide layer for long. Focus position of the laser beam is often at the bottom of material compared to the top of material in laser cutting with oxygen in order to provide required energy to melt the material effectively. Nitrogen has to be applied at higher pressures than oxygen for effective removal of melt.
The cutting nozzle is the key to success. It forms the cutting gas jet and thus determines the cut quality.
Our LASERLINE ® program offers laser users a complete package including appropriate gases, customized gas supply and comprehensive applications support.
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