Nitrogen is the most common assist gas after oxygen in laser cutting — but the purity requirement depends entirely on what you cut and what the edge must look like afterward. Here is the practical breakdown.
Why Nitrogen at All?
As an assist gas, nitrogen blows molten material out of the kerf and — crucially — excludes oxygen from the cut zone. That is what produces the bright, oxide-free edge. Oxygen cutting is faster on thick carbon steel, but it leaves an oxidized edge that must be ground or pickled before welding or powder coating. Nitrogen eliminates that step.
Purity Requirements by Material
| Material | Thickness | Recommended purity | Typical pressure |
|---|---|---|---|
| Carbon steel | 0.5–3 mm | 99–99.5% | 10–14 bar |
| Stainless steel | 0.5–3 mm | 99.99–99.999% | 12–16 bar |
| Stainless steel | 3–12 mm | 99.995–99.999% | 14–18 bar |
| Aluminum | 0.5–6 mm | 99.99%+ | 14–20 bar |
| Brass / copper | 0.5–3 mm | 99.99%+ | 14–18 bar |
Why the jump at stainless? Even 0.1% oxygen in the gas is enough to form chromium oxide scale on the cut edge, discoloring it and degrading corrosion resistance. For food-grade and architectural stainless, 99.995%+ with a low dew point (-50 °C or better) is the safe specification.
Sizing the Generator: Nozzle Flow First
Flow is determined by nozzle diameter and pressure, not by laser power:
- 1.0–1.5 mm nozzle @ 12–14 bar: ≈ 10–25 Nm³/h per head
- 2.0 mm nozzle @ 14 bar: ≈ 35–50 Nm³/h per head
- 3.0–4.0 mm nozzle @ 15–18 bar: ≈ 80–150 Nm³/h per head
Add all heads, add 20% margin, and size the buffer tank so the PSA system does not cycle on every pierce. XINRUI laser packages include the compressor, dryer, PSA towers, booster and buffer tank as one engineered skid — sized from your actual cutting schedule, not a catalog page.