+31 40 8080 193cutting with nitrogen or oxygen with a fiber laser? The cutting gas determines the cutting edge, the speed, and the maximum thickness. Oxygen cuts thick structural steel thanks to an exothermic reaction, while nitrogen provides a clean, oxide-free edge on stainless steel and aluminum. In this guide, you will learn when to choose which gas.
Table of contents
Nitrogen or oxygen cutting: what is the difference?
With nitrogen or oxygen cutting, everything revolves around the reaction at the cutting edge. Oxygen partially burns the metal (exothermic), thus cutting thicker with less power, but leaves an oxide layer behind. Nitrogen is inert: it blows away the molten pool without oxidation and produces a clean edge.
| Cutting gas | Advantage | Disadvantage | Best for |
|---|---|---|---|
| Oxygen (O₂) | Thicker cutting, less power | Oxide layer on the edge | Thick structural steel |
| Nitrogen (N₂) | Clean, white edge | Higher gas consumption and power | Stainless steel and aluminium |
| Compressed air | Economical to use | Limited thickness and quality | Thin material |
When do you choose oxygen?
Oxygen is the choice for thick structural steel. The exothermic reaction generates extra heat, allowing you to cut thicker material with the same power — up to 60 mm at 6 kW. The dark oxide layer on the edge is usually not a problem for structural work, but sometimes requires post-processing during painting or welding.
When do you choose nitrogen?
Nitrogen is used for stainless steel and aluminium, and wherever a clean, immediately workable cutting edge matters. Gas consumption is higher and you need more power for the same thickness, but the quality of the edge is excellent without post-processing.
Compressed air as a cost-effective alternative
For thin sheet metal, compressed air is a cost-effective alternative. It contains approximately 78% of nitrogen and provides a reasonable edge on thin material at a low cost. For thicker or high-quality work, pure nitrogen or oxygen remains the better choice.
The right cutting gas for your work
Which gas is best suited depends on your equipment and the required power. Therefore, also consider which laser power you need and the comparison fiber or CO₂ for metal cutting. You can read more background about the process at Wikipedia on laser cutting.
Frequently Asked Questions
Why does nitrogen produce a cleaner cutting edge?
Nitrogen does not react with the metal and blows away the molten material without oxidation. As a result, you get a clean, oxidation-free edge that you can process further immediately.
Can you cut structural steel with nitrogen?
Yes, with air or nitrogen you cut structural steel with a clean edge, but to a thinner thickness than with oxygen. At 6 kW, you achieve approximately 45 mm with nitrogen or air, compared to 60 mm with oxygen.
Is compressed air just as good as nitrogen?
For thin material, compressed air is a cost-effective alternative, but for thicker or high-quality work, nitrogen provides a cleaner and more reliable cutting edge.
The choice between nitrogen and oxygen cutting also affects your operating costs. Oxygen is cheap, but you consume large quantities of nitrogen at high pressure, which increases the cost per meter. Many companies therefore generate their own nitrogen using a nitrogen generator to reduce their gas bill.
Unsure about a specific material? A short cutting test immediately shows which gas offers the best combination of speed, edge quality, and cost. MetaQuip helps you make that decision based on your own sheets and thicknesses.
Cutting gas and cutting quality in practice
In addition to the choice of gas, the gas pressure, nozzle diameter, and focus position also determine the final cutting quality. Pressure that is too low leaves burrs behind, while pressure that is too high wastes gas. For nitrogen, you generally use high pressure for a clean edge, while for oxygen, you use lower pressure.
In practice, you put together a recipe for each material and thickness: gas, pressure, power, and speed. Modern fiber lasers store these parameters, allowing you to quickly switch between, for example, thick structural steel on oxygen and thin stainless steel sheet on nitrogen.
