What settings does laser cutting aluminium need?
Updated:
Short answer
Aluminium cuts with nitrogen at high pressure, similar to stainless, but its high reflectivity and thermal conductivity mean it needs more power margin for the same thickness and is far less forgiving of a dirty lens or slightly off focus — both cause a lost cut, not just a quality drop.
Why aluminium is harder to cut than steel
| Symptom | Likely cause | First action |
|---|---|---|
| Cut suddenly stops penetrating mid-part with no warning. | High reflectivity sends power back toward the optics; a marginal setup fails abruptly rather than degrading gradually. | Run more power margin for the thickness than a steel table would suggest, and keep the lens spotless. |
| Rough or melted edge on thin sheet. | High thermal conductivity spreads heat sideways faster than in steel. | Increase speed relative to a steel setting of the same thickness to keep heat input local. |
| Dross that is hard and difficult to remove. | Aluminium oxide forms fast and re-solidifies quickly once nitrogen flow drops off. | Keep nitrogen pressure high and consistent through the whole cut, including corners. |
| Frequent lens damage on aluminium jobs specifically. | Reflected beam energy is more aggressive on optics than with steel. | Inspect the protective glass more often on aluminium-heavy schedules than the general maintenance interval. |
Aluminium cutting parameters by thickness and alloy — inside the app. Open SBM Laser Help →
Or take it with you:
Aluminium cutting (5052/6061) — typical starting ranges, nitrogen, 6 kW fiber
| Thickness | Nozzle | Nitrogen pressure | Focus vs surface | Speed |
|---|---|---|---|---|
| 1 mm | 1.5–2.0 mm double | 14–16 bar | −0.5 mm | 20–28 m/min |
| 3 mm | 2.0 mm double | 16–18 bar | −1.5 mm | 7–10 m/min |
| 6 mm | 2.5 mm double | 18–20 bar | −3 mm | 3–4 m/min |
| 10 mm | 2.5–3.0 mm double | 20–22 bar | −5 mm | 1.3–1.8 m/min |
Alloys with more silicon or magnesium (5xxx/6xxx vs 1xxx) shift these ranges — start conservative and adjust from a clean test cut.
Related questions
- Can I cut aluminium with oxygen instead of nitrogen?
- Technically yes on thin sheet, but the edge oxidises heavily and burns unevenly. Nitrogen is the practical standard for aluminium above a millimetre or two.
- Why does my machine handle steel fine but struggle with aluminium at the same power?
- Reflectivity and conductivity, not raw thickness — aluminium needs meaningfully more margin than the steel number for the same thickness.
- Does anodised or painted aluminium cut differently?
- The coating burns off in the kerf and can leave residue at the edge; for critical parts it is worth testing on a scrap piece rather than assuming bare-metal settings apply unchanged.