Fine-tuning the cutting parameters
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.