Nitrogen is often chosen over oxygen for applications where cut quality and finish are paramount. Here’s why:

• No oxidation: As an inert gas, nitrogen displaces oxygen in the cutting zone, helping prevent oxidation and discolouration on the cut edge. This is especially important for stainless steel, aluminium, and coated metals.
• Improved edge quality: The high-pressure nitrogen flow helps remove molten metal from the kerf, resulting in smoother, burr-free cuts that require little to no post-processing.
• Material versatility: Nitrogen works well across a range of materials and thicknesses, making it a flexible choice for workshops handling diverse cutting tasks.

There’s no one-size-fits-all answer when it comes to nitrogen consumption in laser cutting. The amount you’ll need depends on several interconnected factors:
 

• Material type and thickness: Thicker materials require higher flow rates and more pressure. For example, cutting 10 mm stainless steel will demand significantly more nitrogen than 1 mm aluminium.
• Laser power and speed: High-powered lasers working at faster speeds tend to consume more nitrogen to maintain edge quality.
• Nozzle size and gas pressure: These directly affect flow rates and the amount of nitrogen used per minute.

To give a rough benchmark: a 2 kW fibre laser may use anywhere between 20 and 40 Nm³/hour of nitrogen, depending on material and cut quality expectations. Multiply this by the hours of operation, and it becomes clear why efficient nitrogen supply is critical—not just for performance, but for cost control too.

Once the nitrogen requirement is estimated, it's worth looking more closely at the settings that influence gas performance and cut quality. From gas pressure to nozzle geometry, the right parameters make a noticeable difference.
 

1. Gas Pressure
Pressure should match both the type and thickness of the material. Stainless steel often requires settings between 8 and 14 bar (116–203 psi). For thinner metals or polymers, lower pressure may be sufficient. Note that this trend reverses with oxygen, where thinner sheets sometimes need higher pressure for ignition.
 

2. Focal Position
The position of the laser’s focal point changes depending on the assist gas. When cutting with nitrogen, the focal point is typically set at the bottom of the material. This promotes efficient ejection of molten metal. With oxygen, the focal point shifts closer to the surface, depending on thickness.
 

3. Nozzle Diameter
Because flow rate increases with the square of the nozzle diameter, even minor adjustments can significantly impact nitrogen consumption. A slightly larger nozzle might allow for lower pressure without compromising quality—saving gas and cost in the long run.
 

4. Nozzle Alignment
Misaligned nozzles can degrade cut quality. For clean, consistent edges, the gas jet must be co-axial with the laser beam. Correct alignment ensures the assist gas shields the beam and evacuates molten material effectively. That said, certain off-axis configurations may be beneficial in niche applications.
 

5. Stand-Off Distance
This is the space between the nozzle tip and the workpiece. A shorter stand-off distance improves gas flow and cut precision. In most cases, it should be less than the nozzle diameter. Longer distances tend to introduce turbulence, reducing edge quality.

The purity of nitrogen matters. Higher purity translates to less risk of oxidation and a better surface finish—especially on stainless steel or polished metals.

• Standard purity levels for laser cutting typically range from 99.99% to 99.999%.
• While ultra-high purity delivers cleaner results, it also comes at a cost. In many cases, 99.99% is more than sufficient.

Balancing purity with performance and budget is part of optimising your cutting setup.