How to Choose the Right Gas for Fiber Laser Cutters

Fiber laser cutting machines have revolutionized the metalworking industry with their precision, speed, and versatility. However, to achieve optimal performance, you need to choose the right assist gas. Here are the factors to consider when choosing the right gas for fiber laser cutting machines.

Understand the role of assist gas

Assist gas affects the cut quality, cutting speed, and the overall efficiency of the process. The main functions of assist gas include:

Ejecting molten material: Assist gas helps remove molten material from the cut, prevents re-solidification and ensures a clean cut.

Cooling the workpiece: The gas cools the workpiece and minimizes the heat-affected zone.

Protecting the lens: The assist gas protects the lens from spatter and debris, maintaining the integrity of the laser optics.

Increasing cutting speed and quality: Different gases interact with the material in various ways, affecting cutting speed and edge quality.

Types of assist gas

The most commonly used assist gases in fiber laser cutting are oxygen (O₂), nitrogen (N₂), and compressed air. Each gas has unique properties and applications.

Oxygen (O₂): Oxygen supports an exothermic reaction with iron, increasing cutting speeds and aiding in cutting thicker materials, and is commonly used for cutting mild steel. It can increase cutting speeds on mild steel and provide better edge quality on thicker materials. However, be aware that oxidized edges may require additional cleaning or treatment and have a higher risk of burning. On thin materials, it may result in a rough surface.

Nitrogen (N₂): Nitrogen acts as an inert gas, preventing oxidation and producing a clean, shiny cut edge, and is used for cutting stainless steel, aluminum, and other nonferrous metals. Nitrogen cutting does not produce oxidation, and produces a smooth edge finish, making it suitable for thin, reflective materials. Its disadvantages are its higher cost compared to oxygen, and slightly slower cutting speeds for thicker materials.

Compressed air: Compressed air combines the properties of nitrogen and oxygen, providing a balance between cost and performance, and is suitable for cutting thin metal materials. Compressed air has a lower operating cost and can provide suitable cutting speeds and edge quality for some applications, but in ferrous materials, there is a risk of oxidation and it is less effective on thick materials.

Factors to Consider When Selecting an Assist Gas

Material Type: For mild steel, oxygen is preferred because it increases cutting speeds through an exothermic reaction. For stainless steel and aluminum, nitrogen is ideal for avoiding oxidation and obtaining a clean edge. For thin metal materials, compressed air is an economical choice.

Material Thickness: For thicker materials, oxygen can significantly increase cutting speeds. For thin materials, nitrogen provides superior edge quality without the risk of burning.

Cutting Speed and Quality Requirements: If high cutting speeds are a priority, oxygen is the preferred choice for mild steel. For applications that require high edge quality, especially stainless steel and aluminum, nitrogen is the best choice. Compressed air provides a balance for less critical applications where cost is a major factor.

Cost Considerations: Oxygen is relatively low cost but may require post-treatment to clean oxidized edges. Nitrogen is more expensive due to purity requirements but reduces the need for post-treatment. Compressed air is the cheapest option but may compromise edge quality and oxidation control.

Environmental and Safety Issues: Ensure proper ventilation and safety measures when using oxygen because it supports combustion. Nitrogen is inert and poses less risk but requires careful handling to avoid asphyxiation. Compressed air systems need to be free of contaminants that could affect cut quality and machine performance.

Choosing the right assist gas for your fiber laser cutting machine helps optimize performance, quality, and cost-effectiveness. If you have any questions or needs regarding fiber laser cutting machines, please contact us.