Assist Gases in Metal Laser Cutting: A Comparison Between Nitrogen and Oxygen

Industrial & Manufacturing Blog

Laser cutting is a standard process in many industrial applications. Some of its primary uses include engraving, cutting, drilling, etching, etc., on various material surfaces, including metal, wood, paper, and plastic. It's highly used because of its versatility, quality of cuts, speed, flexibility, and precision, among other benefits. Typically, laser cutting, especially metals, requires an assist gas blown over the material surface to remove any molten matter that may interfere with the quality of cuts and dissipate any excess heat from the material surface that could damage it. Generally, nitrogen and oxygen are the primary assist gases used in metal laser cutting. Knowing their differences will enable you to select the correct one for your needs, and here's a comparison guide to help you.

Cutting Speeds

Speed is one of the top benefits of using laser cutters. Generally, how fast you need to get done with your project will help you choose the correct option between the two assist gases. Oxygen is not as non-reactive or inert as nitrogen. Therefore, it results in an exothermic reaction during laser cutting that produces more heat. And with more heat, the cutting process relatively speeds up. Therefore, use oxygen if you are after higher speeds.

Clean Cutting

Clean cuts are crucial in the laser cutting process. It's imperative to create a high-quality cut by preventing irregularities or impurities during the cutting process. Generally, nitrogen is the better option of the two when it comes to creating clean cuts and edges. Due to its inert properties, the gas doesn't promote exothermic reactions like its oxygen counterpart. Consequently, this prevents oxidation or discolouration that is common when using oxygen. Therefore, using nitrogen as the assist gas in your laser cutting project will leave much cleaner edges ready for painting or welding.

That means nitrogen eliminates the need for secondary processes like de-scaling measures to eliminate the oxidised surfaces (after oxygen laser cutting) that tend to be unattractive and undesirable. Therefore, you will have much less prep time before painting or welding the metal. Worth noting is that since nitrogen is inert, it's recommended for high-pressure cutting.

Material

The material you intend to cut can also guide you towards the ideal assist gas to use. For instance, oxygen tends to work better for thicker materials like carbon steel. This is because the extra heat produced from its exothermic reactions is crucial to penetrate thick materials.

Keep in mind that the purity of the gases is essential for the best results whether you use nitrogen or oxygen. Therefore, ensure you go for the purest versions of your assist gases.

11 August 2021