The first lasers used for metal cutting and welding were carbon dioxide (CO2) lasers. They use CO2 gas - mixed with helium and nitrogen - to generate the laser radiation. This is produced by means of an electrical discharge in the gas, whereby the CO2 molecules emit the laser radiation and the nitrogen and helium contribute to a stable and efficient process. With a wavelength of 10.6 micrometers, the laser beam is not visible. In order to bring the laser beam to the focus lens in the cutting head, it needs to be transmitted by flight tubes purged with a clean dry gas or air, using specially coated and cooled mirrors which need to be carefully aligned. The wavelength of the CO2 laser means it can cut most metals except those that have a very high reflectivity in the infrared spectrum, such as gold and copper.
Laser Cutting with LASERLINE
Channeling Application Expertise into Custom-developed Process Gases
Flexible, High-quality Solutions to Extend the Profitability and Lifetime of Your Expensive Laser Cutting Equipment
Laser cutting is a state-of-the-art technology used for high-power cutting of metals and non-metals worldwide. Typical applications include cutting of hydro-formed parts and tubes, high-speed cutting of thin sheet metals and cutting of thick-section materials. The benefits of laser cutting include improved cutting speeds, low levels of tool wear and greater flexibility.
The gases used to generate the laser beam and expel the molten metal out of the cut kerf are important consumables during laser operations. They can prolong the lifetime of optical components, increase the cutting speed and improve the cutting quality. Using cutting gases properly can thus contribute to more profitable laser operations
Getting Your Cutting Gases Right
We are a leading supplier of laser cutting and process gases to customers all around the world. Highlights include our specialty premixed LASERMIX® laser gas mixtures. Our experts can help you choose the laser and cutting gases and supply solutions that best fit your laser cutting needs.
Developed specifically to support laser cutting applications, our LASERLINE® series unites our in-depth laser cutting know-how with our long-standing experience in the delivery of fully integrated laser solutions. Engineered to meet your purity and reliability needs, our offering extends from process consulting through gas storage and supply technologies to all-round technical support. The result is a state-of-the-art, all-inclusive supply and service package with the potential to help boost your performance and efficiency while protecting your investment in expensive laser equipment.
CO2 Lasers - A Closer Look
Solid-state Lasers - A Closer Look
Solid-state lasers include fiber and disc lasers. First developed at the end of the 20th century for telecommunications purposes, fiber lasers have since been scaled up tremendously to rival and exceed carbon dioxide (CO2) lasers in terms of power. Several variants, such as disc lasers, have also been developed. Fiber lasers have no moving parts and require no laser resonator gas. With a much shorter wavelength than CO2 lasers, at around 1 micron, fiber lasers are just outside the visible range. This shorter wavelength makes them ideal for 3D cutting and welding applications as flight tubes and mirrors are not required. They can also cut thin mild and stainless steels much more efficiently than CO2 lasers. However, they produce poor-quality edges when cutting thick sheets.
Laser Cutting Gases
Laser cutting depends on an assist gas, which may be active or inert. Oxygen(O2) is the standard active assist gas used for laser cutting of mild and carbon steels. It is also referred to as the cutting gas.
When cutting with O2, the material is burned and vaporized after being heated up to ignition temperature by the laser beam. The reaction between the O2 and the metal actually creates additional energy in the form of heat, which supports the cutting process. The liquid iron oxide, which has very low viscosity, is removed from the cut by the shear force of the O2 jet.
The pressure of the O2 can be increased in order to improve the melt-shear removal process. This increase is not, however, limited by the cooling effect caused by the gas, but by the increase in sideways burning due to the higher O2 concentration. This can result in bad cuts with significant dross or no cut at all.
The maximum O2 pressure depends primarily on the material thickness. For thin sheets up to 2 or 3 mm, O2 pressure can be as high as 20 bar, where the contribution of the combustion process is insignificant and the melt-shear removal process does all the work. For thick sheets, however, the maximum applicable O2 pressure drops rapidly. At thicknesses above 20 mm, the applied pressure is rarely over 1 bar (gauge).
Getting Oxygen Purity Right for Enhanced Laser Cutting Productivity
Industrial oxygen is typically supplied in cylinders with a minimum purity of 99.5%. Generally speaking, this is not sufficient for laser cutting as it does not result in the best cut quality or the fastest cutting speeds.
Our LASERLINE® process gases were developed specifically to meet your oxygen purity needs in laser cutting, thus helping to increase your productivity and accelerate return on investment. We also work closely with laser manufacturers to ensure that our LASERLINE gases meet OEM purity requirements.
Our minimum specification for oxygen purity for laser cutting is 99.95%, based on the knowledge that there is little to be gained by increasing purity any higher.
Many laser cutting applications rely on non-reactive (inert) gases as the assist gas. Nitrogen (N2) would be the typical choice for cutting stainless steel, aluminum and aluminum alloys.
Cutting with non-reactive gases is often referred to as clean cutting or high-pressure cutting. Here, the material is melted solely by the laser power and blown out of the cut kerf by the kinetic energy of the gas jet. Unlike cutting with oxygen, the melt-shear removal process is the only active process as inert gases do not react with the molten metal and no additional heat is generated. Therefore much higher laser power and gas pressures are required - also because the molten steel has quite a high viscosity compared with liquid iron oxide.
With nitrogen cutting, increasing the N2 pressure will result in faster cutting speeds. This speed gain is limited by the cooling effect of high-pressure gas flows. For mild steel and stainless steel thick sheets, the ideal pressure lies in the region between 10 and 15 bar. Higher figures are possible with the most powerful lasers available.
Meeting your Nitrogen Purity Challenges for Enhanced Laser Cutting Outcomes
The N2 purity is important if a clean cut edge is required, for example when cutting stainless steel or aluminum metals. Even small percentages of oxygen contamination will result in yellowing of the cut edge in stainless steel as a result of oxidation. Also, more dross may be formed and this is difficult to remove.
The oxygen content in nitrogen becomes even more critical when very thick sections of stainless steel are being cut. Due to the lower cutting speeds, the material is able to react with the oxygen for longer. Hence a minimum N2 purity of 99.995% is often required.
We deliver our LASERLINE® process gases to meet your specific N2 purity needs - designed to help you enjoy greater productivity and faster return on investment. We also work closely with laser manufacturers to ensure that our LASERLINE gases meet OEM purity requirements. Our minimum specification for N2 purity for laser cutting is 99.998%.
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