Laser Cutting Process and Assist Gases: Why You Need Nitrogen for Laser Cutting
Laser cutting is a thermal process with many applications in the world of industrial manufacturing. Laser cutting machines are capable of quickly engraving and cutting metal sheets, even with the most complex shapes, offering high-quality finishes.
In this wiki article, we will explore the laser cutting process, techniques, and assist gases, including nitrogen, oxygen, and compressed air, to help you understand how it works and its benefits.
What is laser cutting?
Laser cutting is a process that uses a high-power laser directed by computer numerical control (CNC) through optics to cut materials. This process is widely used in various industries, including automotive, aerospace, electronics, and medical, to cut materials such as metals, plastics, ceramics, wood, fabrics, and paper.
Laser cutting involves using a focused laser beam to melt material in a localized area, with the help of a co-axial gas jet, and create a kerf. The laser beam itself remains unaffected by gas, but it can effectively burn, melt, or vaporize materials, while any resulting debris can be blown away, ensuring a high-quality finished edge.
Laser cutting can also be used for welding and etching. The three main techniques for laser cutting are CO2 laser, neodymium (Nd), and neodymium yttrium-aluminium-garnet (Nd:YAG) lasers. The type of laser used can affect laser performance. The advantages of laser cutting include precision, accuracy, reduced contamination, and easier workholding. Fiber lasers, in particular, are known for their superior precision cutting capabilities. One of the key advantages of fiber lasers is their ability to deliver consistent beam quality over long distances, enabling uniform cutting across various materials and thicknesses. This consistency contributes to superior edge quality and minimizes the need for secondary processing.
How does a laser cutting machine work?
Laser cutting machines work by directing a high-powered laser beam through optics and onto the material to be cut. The laser beam is focused through a lens and projected onto the material, melting or vaporizing it in a localized area due to the rapid temperature rise. The material is then removed by a co-axial gas jet, which blows away the molten material and creates a kerf. The gas jet also helps to cool the material and prevent it from warping or distorting. The laser cutting machine is controlled by a computer numerical control (CNC) system, which ensures precision and accuracy in the cutting process.
What are assist gases in laser cutting?
Assist gases are used in laser cutting to improve the quality and efficiency of the cutting process. The assist gas helps to blow away the molten material and prevent it from re-solidifying on the surface of the material. It also helps to cool the material and prevent it from warping or distorting. The most commonly used assist gases in laser cutting are nitrogen, oxygen, and compressed air.
1. Use of nitrogen in laser cutting
Nitrogen is the most widely used assist gas in laser cutting, thanks to its inert properties. It is used to ensure a high-quality performance of the laser, particularly when a high-quality cut is required. Nitrogen eliminates oxygen in the air and thus prevents it from reacting with the hot metal, resulting in a perfect, shiny cut, without affecting the color of the material (this will depend on the purity of nitrogen used). Nitrogen gas, being inert, keeps the cut edge from oxidizing by enabling the laser to run in an oxygen-free environment. Nitrogen is also essential for lower cost, higher cutting speed, higher productivity, better control, highest efficiency, on-demand nitrogen, and a plug-and-play solution.
2. Use of oxygen in laser cutting
Oxygen is used in laser cutting to cut materials that are difficult to cut using other methods. Oxygen is a highly reactive gas and causes an exothermic reaction by multiplying the power of the laser beam, allowing thicker materials to be cut. Oxygen reacts with the material being cut, creating a chemical reaction that helps to melt and vaporize the material. Depending on the material, oxygen is also used to increase the cutting speed and reduce the cost of the cutting process. However, oxygen can cause oxidation, which can cause a carbon layer to form on the cut edge, resulting in poor product finish and adhesion problems for any coating or paint applied to the oxidized surface. Due to the high reactivity of oxygen, very thin slices cannot be obtained.
3. Use of compressed air in laser cutting
Compressed air can also be used as an assist gas in laser cutting and can be faster and more cost-effective for laser cutting. However, it does not allow to obtain parts with very clean cuts because air has 21% oxygen in its composition (normally, these parts need be deburred before the next process, which takes some extra labor). These cuts are valid in parts that are later going to be painted or welded, in which the color of the cutting edge does not matter.
What are the usual assist gas purities?
The purity of the assist gas will depend on the customer's requirements for the final product, although we must consider that:
- If we use atmospheric air the purity of the air cannot be changed, we will have 78% nitrogen and around 21% oxygen.
- If we use oxygen, we're generally going to have purities above 99.5%.
- And if we use nitrogen, it will depend on the material to be cut, whether the material is going to be treated afterwards, the importance of the color of the cutting edge, etc.
Bearing in mind that, by decreasing the purity of the nitrogen, we will reduce the cost significantly.
Can an assist gas such as nitrogen be generated in the plant?
Yes, it is feasible to generate your own assist gas like nitrogen within the plant premises. By integrating a high-pressure gas generation system into the facility, companies can ensure a continuous supply of gas, available round-the-clock, 24 hours a day, 7 days a week. This approach not only reduces operational expenses but also affords complete control of gas consumption. Furthermore, by eliminating the need for truck transportation, companies can significantly reduce CO2 emissions, contributing to environmental sustainability.
Nitrogen generators for laser cutting
Nitrogen generators are essential for optimizing laser cutting operations, offering a range of practical benefits. There are two kinds of nitrogen generators, membrane and PSA (Pressure Swing Adsorption) nitrogen generators, which make it possible to achieve very high levels of purity.
Businesses that use nitrogen in laser cutting can significantly reduce costs by generating their own nitrogen supply, eliminating the need for external purchases. This in-house production also ensures greater control over nitrogen purity, guaranteeing consistent quality without dependence on external suppliers.
Moreover, by producing nitrogen on-site, companies contribute to environmental sustainability by reducing transportation emissions and minimizing reliance on traditional nitrogen production methods. Overall, the use of nitrogen generators is a pragmatic choice for companies looking to enhance efficiency and environmental responsibility in laser cutting processes.
High-pressure compressors and boosters for laser cutting
Laser cutting machines often rely on compressed air or gases for various functions, including powering the laser itself. High-pressure compressors and boosters provide the necessary compressed air or assist gases like nitrogen for the laser cutting process. They ensure a consistent and reliable power source for the laser, contributing to stable and precise cutting. High-pressure compressors are used to compress gases like nitrogen or oxygen for assisted laser cutting. Pressurization of assist gases enhances laser the cutting process and facilitates the delivery of high-pressure gases to the cutting head for optimal performance.
Laser cutting systems often incorporate high-pressure compressors or booster as part of an integrated solution for a streamlined and efficient setup for laser cutting applications. Integrating high-pressure compressors with laser cutting systems provides a comprehensive solution for your industrial needs.
Contact Us Today
Atlas Copco has a wide range of reliable, high-purity on-site gas generators and high-pressure gas generation systems for all your nitrogen and oxygen needs for laser cutting.
If you have any questions or would like to learn more about laser cutting and our nitrogen and high-pressure solutions, please contact us today. Our team of experts is always ready to help you find the best solution for your needs.