How-to
How to Cut Stainless Steel with a Laser (Setup and Troubleshooting)
Updated 2026-10-13 · 4 min read
Every material has a way of telling you what it wants, and stainless steel is unusually clear about it: it wants nitrogen, it wants pressure, and it wants you to stop cutting it too slowly. Get those three right and the edge comes out silver and weldable. Get them wrong and you get dross, discolouration or a cut that does not go through.
Quick answer: Cut stainless with nitrogen at high pressure (10–20 bar depending on thickness), not oxygen. Set focus slightly below the surface, run the speed up until dross disappears, and check nitrogen purity — 99.99% or better for a bright edge. Yellow or blue edges mean oxidation from low pressure, low purity or too little speed.
Why stainless behaves differently from carbon steel
Three material properties drive the whole setup.
There is no exothermic reaction to help you. Carbon steel is cut with oxygen, and the oxidation of iron releases heat that does much of the cutting work. Stainless contains chromium, which forms a tenacious oxide that resists that reaction. So the laser has to supply essentially all the energy, which is why the same machine cuts stainless at roughly half the speed of carbon steel at the same thickness.
It conducts heat away quickly. Energy that would melt the kerf bleeds into the surrounding sheet. That is one reason thin stainless distorts and why piercing needs care.
Nitrogen must physically blow the melt out. With no chemical assistance, the kerf is cleared purely by gas pressure. If pressure drops, molten material stays in the kerf and freezes as dross.
Nitrogen or oxygen: pick deliberately
| Nitrogen (N₂) | Oxygen (O₂) | |
|---|---|---|
| Edge quality | Silver, oxide-free, weldable | Oxidised, grey or black |
| Cutting speed | Baseline | Faster on thick material |
| Gas cost | Higher (high pressure, high purity) | Lower |
| Post-processing | None needed for welding | Must be ground or pickled |
| Typical use | Stainless, aluminium | Carbon steel; thick stainless where edge does not matter |
Default to nitrogen. Reach for oxygen only when the edge is hidden, will be painted, or will be machined off — and when speed on thick material genuinely matters more than the edge.
Starting parameters for stainless
A focused subset. The full parameters chart covers every material and thickness.
| Thickness | Power | Speed | Focus | N₂ pressure |
|---|---|---|---|---|
| 1 mm | 1–1.5 kW | 5–7 m/min | −0.3 mm | 8–10 bar |
| 2 mm | 2 kW | 2.5–3.5 m/min | −0.8 mm | 10–12 bar |
| 3 mm | 3 kW | 2.0–2.5 m/min | −1.2 mm | 12–14 bar |
| 5 mm | 3–4 kW | 1.3–1.8 m/min | −2.0 mm | 14–16 bar |
| 8 mm | 6 kW | 1.5–2.0 m/min | −3.0 mm | 16–18 bar |
Notice the pressure climbing with thickness. On thin sheet, 8 bar clears the kerf easily. On 8 mm you need roughly double that, because the melt has much further to travel out.
Setting it up, in order
Work through these in sequence. Changing two things at once is how parameter setting turns into an afternoon.
- Clean the optics and fit a fresh nozzle. A contaminated protective lens or a worn nozzle ruins every setting downstream. This is the cheapest step and the most commonly skipped.
- Check nitrogen purity and pressure at the machine. Not at the regulator on the wall — at the cutting head. A leak or a partially closed valve shows up here and nowhere else.
- Set focus slightly negative. Start at −0.5 mm for thin sheet and go further negative as thickness rises.
- Get through the material first. Raise power or lower speed until the cut goes cleanly through across the whole part. Ignore edge quality for now.
- Tune speed for the bottom edge. Increase in 5–10% steps until dross starts to appear, then back off. That is your maximum clean speed.
- Tune focus for the top edge and kerf width. Move in 0.5 mm steps; the sweet spot gives the narrowest kerf with a square top edge.
- Fine-tune pressure last. If dross persists at the right speed and focus, raise pressure in 1 bar steps.
- Write it down. Put the final parameters in the machine library keyed to material and thickness.
Reading the cut edge
The edge colour is a diagnostic instrument. Learn to read it and you will stop guessing.
| Edge appearance | What it means | What to change |
|---|---|---|
| Bright silver, uniform | Correct | Nothing |
| Pale straw / light gold | Slightly hot | Increase speed ~5% |
| Blue or purple | Oxidising | Increase speed; check N₂ purity and pressure |
| Brown or black | Heavy oxidation | Check gas supply and purity; increase pressure |
| Grey and rough | Speed too high, or pressure low | Reduce speed; raise pressure |
| Dross on the bottom | Melt not expelled | Reduce speed 5–10%; raise pressure; check nozzle |
| Heavy, hard dross | Focus too low, or nozzle damaged | Raise focus 0.5 mm; replace nozzle |
| Kerf wider than expected | Focus too high | Lower focus 0.5 mm |
Piercing thick stainless
Piercing is where most problems on 4 mm and above originate. A single-stage pierce at full power spatters molten metal upward onto the nozzle and lens.
- Use a two-stage pierce above about 4 mm: a low-power stage to establish the pierce, then full power to cut.
- Set the pierce height higher than the cutting height, so spatter clears the nozzle.
- Consider a pierce point off the part on visible work, so the pierce mark does not end up on the finished edge.
- Check the nozzle after a run of thick piercing. Spatter damage is cumulative and silent.
Common problems and their causes
Cut not going through, sparks spraying upward. Speed too high, or focus too low. Reduce speed 10% or raise focus.
Random misses and inconsistent cuts. A damaged nozzle changing the gas flow. Replace it — do not try to tune around it.
Thin sheet distorting. Too much heat input. Raise speed, reduce power if the machine allows, and check the sheet is held flat.
Dross only on one side of the part. Usually the gas flow is asymmetric, often from a partially blocked nozzle or a misaligned head. Check nozzle concentricity.
Edge quality degrades over a shift. Thermal drift in the cutting head or a contaminated protective lens. Recheck focus and inspect the lens.
Frequently asked questions
Can a laser cut stainless steel?
Yes. A fiber laser cuts stainless steel from around 0.5 mm up to roughly 12 mm on a 3 kW source and 20-25 mm on 6-12 kW, using nitrogen as the assist gas. CO2 lasers can cut thin stainless but far more slowly and with a rougher edge.
What gas do you use to cut stainless steel?
Nitrogen, at high pressure - typically 10 to 20 bar depending on thickness. Nitrogen is inert, so it prevents oxidation and gives a clean, weldable edge. Oxygen is sometimes used for speed on thick stainless but leaves an oxidised edge that must be pickled before welding.
Why is my stainless cut discoloured?
Yellow or brown discolouration is oxidation, caused by insufficient nitrogen pressure, nitrogen purity below 99.99%, or cutting too slowly so the material stays hot. Increase pressure, check gas purity, and increase speed until the edge is silver.
Why does stainless steel get dross on the bottom?
Usually the molten material is not being expelled fast enough. Reduce cutting speed by 5-10%, raise nitrogen pressure, or lower the focus slightly. A worn nozzle causes the same symptom and should be replaced first.
Can you weld laser-cut stainless steel?
Yes, if it was cut with nitrogen. Nitrogen-cut edges are oxide-free and weld directly. Oxygen-cut edges carry an oxide layer that must be ground or pickled off first.
Machines mentioned in this article
- Fiber Laser Cutting Machine — PL-1390 fiber laser for stainless sheet
- Laser Accessories & Spare Parts — Nozzles, protective lenses and chillers for stainless work
- Cutting Parameters Chart — Full starting parameters for all materials
- 304 vs 316 Stainless — Why the two grades cut differently
Related guides
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