October 29, 2026 · Technical Guide
Laser Cutting Aluminum Sheet: Power, Nitrogen and Edge Quality
Aluminum sheet cuts clean on a fiber laser when three things are right: enough power, high pressure nitrogen and a focus point slightly below the surface. For 1 to 3 mm 5052 or 6061, a 2 to 3 kW source at 12 to 15 bar runs 20 to 30 m/min and leaves a square edge with no dross. The old line that aluminum is too reflective to cut is a CO2 story, and it does not apply to a 1 micron fiber beam.
I quote these machines most weeks, and the same three questions come back every time. Hopefully this saves you a few emails.
Why do people still say aluminum is hard to laser cut?
Because for about 30 years it was. A CO2 laser works at 10.6 micron, and bare aluminum reflects most of that wavelength. Shops got ragged edges, high gas bills and burnt lenses, so the rule became: aluminum is a plasma or waterjet job.
A fiber laser runs at about 1.07 micron. Aluminum absorbs more there, and absorption climbs the moment the surface melts. That is why a 3 kW fiber source cuts 3 mm aluminum faster than a 4 kW CO2 ever did.
Two real problems remain, and they are not about reflection:
- Heat runs away. 6061-T6 conducts about 167 W/m·K against roughly 50 W/m·K for mild steel, so the sheet pulls heat away from the kerf. Thin aluminum needs speed, not brute power.
- The oxide skin fights you. Aluminum oxide melts near 2,072 °C while the metal under it melts at 660 °C. High pressure nitrogen and a clean nozzle get through it, low pressure does not.
Sheets and coils we cut most are on the aluminum alloy page, with grades, tempers and thickness tolerance in one place.
How much laser power do you need for which aluminum thickness?
The table below is the range we set up on customer floors, nitrogen cutting, 5052 or 6061, good edge quality. Treat it as a starting point for your own material and finish.
| Thickness | Power | Typical speed | N2 pressure |
|---|---|---|---|
| 1.0 mm | 1 - 1.5 kW | 35 - 45 m/min | 10 - 12 bar |
| 1.5 mm | 1.5 - 2 kW | 28 - 35 m/min | 10 - 13 bar |
| 2.0 mm | 2 - 3 kW | 20 - 28 m/min | 12 - 14 bar |
| 3.0 mm | 2 - 3 kW | 12 - 18 m/min | 12 - 15 bar |
| 4.0 mm | 3 - 4 kW | 9 - 13 m/min | 14 - 16 bar |
| 5.0 mm | 3 - 4 kW | 7 - 10 m/min | 15 - 16 bar |
| 6.0 mm | 4 - 6 kW | 5 - 7 m/min | 15 - 18 bar |
| 8.0 mm | 6 - 8 kW | 3.5 - 5 m/min | 16 - 18 bar |
| 10.0 mm | 8 - 12 kW | 2 - 3 m/min | 18 - 20 bar |
| 12.0 mm | 12 kW and up | 1 - 1.8 m/min | 18 - 20 bar |
Two notes before you copy a row into a PO. First, a 3 kW fiber laser cutting machine cutting 3 mm all day on two shifts is working hard. Take one size up and it lasts. Second, these speeds assume good nesting and few piercings. A part with 200 small holes will run slower than the chart, because every pierce costs time on aluminum.
If you want the full speed curve by power, it is in our cutting speed and thickness chart.
Nitrogen, compressed air or oxygen: which gas for aluminum?
| Gas | Edge you get | Cost | Best for |
|---|---|---|---|
| Nitrogen 99.99% | Bright, oxide free, weldable | Highest gas cost | Anodizing, welding, painting, visible parts |
| Compressed air | Light grey oxide, slightly rough | Cheapest, needs a dryer | 1 - 3 mm brackets, painted parts |
| Oxygen | Heavy oxide, dross on aluminum | Low | Not recommended, use it for carbon steel |
Oxygen is the one to avoid on aluminum. It works on carbon steel because the exothermic reaction helps, but on aluminum it leaves a black, hard oxide edge that ruins anodizing and clogs a weld prep. We supply oxygen setups for steel and nitrogen for aluminum, not one gas for both.
Air cutting is a real option and I recommend it more than people expect. A 2.2 kW screw compressor with a refrigerated dryer covers most thin sheet work, and the running cost is a fraction of nitrogen. The catch: the edge is oxidized, so no anodizing and no cosmetic parts.
What nitrogen pressure and nozzle size do you need?
Aluminum wants pressure, not flow. Two numbers to hold in your head:
- Pressure: 12 to 15 bar for 1 to 3 mm, 16 to 20 bar for 5 mm and up
- Nozzle: 1.2 to 1.5 mm single layer for thin sheet, 1.5 to 2.0 mm for 5 mm and up
| Nozzle | N2 flow at 15 bar | Gas cost per hour* | Suits |
|---|---|---|---|
| 1.0 mm | about 14 Nm³/h | about USD 4.9 | 1 - 2 mm, low power |
| 1.2 mm | about 20 Nm³/h | about USD 7.0 | 2 - 3 mm |
| 1.5 mm | about 31 Nm³/h | about USD 10.9 | 3 - 6 mm |
| 2.0 mm | about 55 Nm³/h | about USD 19.3 | 6 - 12 mm |
*At USD 0.35 per Nm³ from an on-site PSA generator. Cylinder or dewar supply runs higher per cubic metre. Your own rate will differ, ask your gas supplier for Nm³ price, not cylinder price.
This is the number that surprises buyers. A 6 kW machine on 6 mm aluminum burns 31 Nm³/h, so an eight hour shift is about 250 Nm³ and roughly USD 87 in gas. Two shifts a day, 300 days a year is over USD 50,000. On thin sheet the gas is small. On 6 to 8 mm it is a line in the budget, and a good reason to look at an on-site generator instead of cylinders.
Why is there dross on the bottom of my aluminum parts?
Dross means the molten metal did not get pushed out before it froze. On aluminum the cause is almost always one of these, in this order:
- Gas pressure too low. Under 10 bar on 3 mm aluminum, expect dross. Simple as that.
- Focus too high. A positive focus leaves a hard dross that will not chip. Move the focus down 0.5 to 1 mm and test again.
- Too slow. Aluminum loses heat fast, but going too slow widens the kerf and the melt pools underneath.
- Dirty lens or nozzle. Aluminum spatter sticks. A partly blocked nozzle gives uneven pressure around the kerf and dross on one side only. Check the nozzle before you touch the parameters.
- Difficult alloy. 2024 and 7075 are copper and zinc rich, and both dross more than 5052 or 6061 at the same settings.
More on the general defects and how to read them: laser cutting defects, dross, burrs and taper.
Does the protective film cause bad cuts?
Yes, and it is one of the sneaky ones. Most aluminum sheet ships with a PE film or paper interleaf. If you cut with film on top and no proper pressure, the plastic melts into the kerf, sticks to the edge and burns.
Three ways to handle it, in order of preference:
- Cut film side down, so the film faces the bed and the beam exits into it
- Leave tabs and peel after cutting, if the parts are large
- Strip the film before cutting on cosmetic parts
If you get black sticky edges, check for film before blaming the gas. I have seen a whole shift of scrap traced to sheet that came in filmed and nobody noticed.
Which aluminum alloys cut well, and which fight back?
| Grade | How it cuts | Note |
|---|---|---|
| 1050 / 1100 / 3003 | Very clean | Soft, low dross, good for thin gauge |
| 5052 / 5754 | Clean | The easiest 5xxx to cut, our default for sheet work |
| 5083 | Good | Marine plate, slightly more dross above 6 mm |
| 6061 / 6082 | Good | Needs stable focus, edge tempers soften locally |
| 2024 / 7075 | Difficult | High copper or zinc, more dross and micro cracks on thick sections |
If your part is 6061-T6 and it carries load, remember the cut edge loses some temper. The softened band is thin, usually under 0.3 mm, but it is there. Design around it or plan a re-age, and say so on the drawing. Grade selection for importers is covered in more detail in our aluminum plate grade selection guide.
What edge quality can you expect for welding and anodizing?
Nitrogen cut, clean machine: Ra 1.6 to 3.2 micrometer on the cut face, square within 0.1 mm on 3 mm sheet, no recast lip you can catch a fingernail on. That is good enough for most fabrication.
Two things matter downstream:
- Anodizing shows every scratch and every oxide smear. Cut with nitrogen, handle with gloves, do not stack fresh parts face to face.
- Welding needs an oxide free edge. A nitrogen cut is fine after a wipe with a stainless brush or a quick solvent clean. An air cut edge needs mechanical cleaning before TIG or laser welding, or you get porosity.
Sheet thickness tolerance matters more than most buyers think for edge fit up. If you are not sure what your drawing should call out, our thickness tolerance guide has the standard numbers.
What about safety on aluminum?
Three things. Aluminum dust from laser cutting is fine and it burns, so the extraction system needs a spark arrestor and a proper dust plan. Never cut without extraction running. And do not cut aluminum with the enclosure open to "watch the first part", because the reflected beam off a shiny sheet is not something to test with your eyes.
If you are still sizing the extraction, the airflow numbers are in our fume extraction guide.
Checklist before you order an aluminum cutting setup
- Give the supplier your thickness range and the alloy you actually buy, not "aluminum"
- Say whether the edge goes to anodizing, welding or paint, because that decides the gas
- Ask for the cutting parameter sheet for your alloy and thickness, in writing
- Confirm nitrogen supply: pressure, purity and whether you buy cylinders or a generator
- Check the machine can hold 15 bar at the nozzle, not just at the regulator
- Ask what nozzle sizes ship with the head, and the spares price
- Run a test cut on your own sheet before you sign, not on their sample
If you send us the alloy, thickness and edge requirement, we will send back the parameters we would run and the gas consumption per hour. That is usually enough to compare two quotes on the same basis. Send your spec here and I will check it.
Frequently Asked Questions
Can you laser cut aluminum sheet?
Yes. A fiber laser at 1 micron cuts aluminum sheet from 0.5 mm up to about 12 mm in normal production, and thicker plate on high power machines. The old warning that aluminum reflects the beam comes from CO2 lasers at 10.6 micron. Once the metal melts, absorption climbs sharply, and a fiber source couples well enough to cut at normal speeds. Our fiber laser cutting machine pages list the power and bed options we build.
What power do I need to cut 3 mm aluminum sheet?
Plan on 2 to 3 kW with 12 to 15 bar nitrogen. That gives roughly 12 to 18 m/min on 5052 or 6061 with a square edge and no dross. If you cut 3 mm all day on two shifts, take 3 kW or 4 kW so the source runs at 70 to 80 percent instead of flat out.
Why is there dross on the bottom of my aluminum parts?
Nine times out of ten it is gas pressure or focus. Aluminum needs 12 bar and up to blow the molten metal out of the kerf. Below that the melt hangs on the underside and freezes. Focus set too high also leaves a hard dross that will not chip off. Check gas pressure first, then focus, then lens condition.
Can I cut aluminum with compressed air instead of nitrogen?
You can, and plenty of shops do on 1 to 3 mm. Air is cheap and the cut is fast, but the edge comes out oxidized and slightly rougher. If the part goes for anodizing, powder coating or welding, use nitrogen. If it is a bracket that gets painted, air is fine.
Does laser cutting weaken aluminum?
The heat affected band on a nitrogen cut is narrow, usually under 0.3 mm on 3 mm sheet, so most parts lose nothing that matters. On 6061-T6 or 7075-T6 the edge does soften locally because the temper drops. If the edge sits in a load path, keep it out of the peak stress area or plan a re-age after cutting. Sheet grades and tempers are listed on our aluminum alloy page.
Related Articles
- Fiber Laser Cutting Speed and Thickness Chart: Real Parameters by Power
- Laser Cutting Defects: How to Fix Dross, Burrs and Taper
- Aluminum Alloy Plate Grade Selection Guide 2026: 1050 to 7075 for Importers
- Aluminum Sheet Thickness Tolerance: What the Standards Allow
- Laser Cutting Fume Extraction: Airflow, Filters and Real Cost
Sources: material properties from ASM Handbook values (6061-T6 thermal conductivity 167 W/m·K, mild steel about 50 W/m·K; aluminum melting point 660 °C, aluminum oxide about 2,072 °C). Wavelength comparison is standard: CO2 at 10.6 micron, fiber sources near 1.07 micron. Cutting speeds, nitrogen pressures and gas consumption in the tables are FANY LASER field ranges from 2026 customer installations on 3015 and 4020 beds with 1 to 12 kW fiber sources, not a guarantee. Gas cost assumes USD 0.35 per Nm³ from an on-site PSA generator. Confirm parameters on your own machine and material before production.