How do I choose the nozzle diameter for laser cutting?
Updated:
Short answer
Nozzle diameter follows thickness and gas: small single nozzles of 1.0–1.5 mm for oxygen cutting of mild steel, larger double nozzles of 1.4–3.0 mm for nitrogen cutting where a wide, high-pressure jet must clear the melt. Too large a nozzle wastes gas and softens the jet; too small starves the kerf.
Signs the nozzle is the problem
| Symptom | Likely cause | First action |
|---|---|---|
| Gas consumption creeps up, burr returns, pressure at the kerf drops. | Orifice enlarged by wear | Measure or gauge the orifice; replace on a schedule rather than on failure. |
| Sudden quality drop after piercing thick plate. | Spatter build-up on the tip | Clean or replace; raise pierce standoff and use ramped piercing to stop it recurring. |
| Quality differs between the two sides of the same part. | Beam off-centre in the orifice | Re-centre with the manufacturer’s procedure after any optics work or collision. |
Nozzle and gas settings per thickness — inside the app. Open SBM Laser Help →
Or take it with you:
Nozzle selection — starting points
| Material and gas | Thickness | Nozzle |
|---|---|---|
| Mild steel, oxygen | 1–3 mm | 1.0–1.2 mm single |
| Mild steel, oxygen | 6–12 mm | 1.2–1.5 mm single |
| Mild steel, oxygen | 16–25 mm | 1.5–2.0 mm single |
| Stainless, nitrogen | 1–3 mm | 1.4–2.0 mm double |
| Stainless, nitrogen | 4–8 mm | 2.0–2.5 mm double |
| Stainless, nitrogen | 10–15 mm | 2.5–3.0 mm double |
Gas consumption scales roughly with the square of the orifice diameter — a 3.0 mm nozzle costs far more per hour than a 2.0 mm one.
Related questions
- What is the difference between single and double nozzles?
- A double nozzle forms a more coherent, higher-pressure jet, which is what high-pressure nitrogen cutting needs. Oxygen cutting of mild steel works with a simpler single nozzle at much lower pressure.
- How often should nozzles be replaced?
- By condition, not by calendar: check the orifice at every consumable inspection. Shops running thick plate with heavy piercing replace far more often than shops on thin sheet.