Laser Cutting
Laser cutting melts, burns or vaporises a narrow kerf through flat stock with a focused beam, producing profiles from a 2D file with no tooling.
- Part
- Cutting
- Revised
- 2026-08-11
At a glance
- Family
- Thermal
- Typical tolerances
- ±0.005 in (±0.13 mm) on thin sheet; ±0.010 in (±0.25 mm) on plate and over long dimensions; edge taper roughly 0.5–1°
- Surface finish
- Edge quality is graded to ISO 9013 (perpendicularity and mean height of profile) rather than Ra; nitrogen-cut stainless is bright and oxide-free, oxygen-cut mild steel leaves an oxide layer
- Typical volumes
- 1–10,000 parts; no tooling, so single pieces are practical and unit cost falls mainly through nesting
- Lead time
- 1–5 business days; same-day is common for simple sheet parts
- Materials
- Metal, Plastic, Wood, Composite
What it is
Laser cutting focuses a beam onto flat stock and melts, burns or vaporizes a narrow kerf through it while an assist gas blows the molten material out the bottom. It needs no tooling — the part comes straight from a DXF — which is why it dominates sheet metal prototyping and short-run fabrication.
Two machine types cover most work. Fiber lasers (1.06 µm wavelength) cut metals: mild steel to about 1 in (25 mm) on common 4–6 kW machines, stainless and aluminum somewhat less, with 10–20 kW machines extending that to roughly 1.5 in (38 mm). CO2 lasers (10.6 µm) cut metal more slowly but are the machine for acrylic, plywood, MDF, leather, paper and textiles.
Kerf runs 0.004–0.015 in (0.1–0.4 mm) depending on thickness, edges come off within about a degree of square, and profile tolerance is ±0.005 in (±0.13 mm) on thin sheet.
How it works
- Nesting and programming. Parts are nested on the sheet to maximize yield, with lead-ins placed in scrap, common-line cutting where two parts can share an edge, and micro-tabs where small parts would otherwise drop and tip.
- Beam delivery and focus. The beam is focused to a spot on the order of 0.004–0.010 in (0.1–0.25 mm). Focus position is set relative to thickness and gas: at or near the surface for thin oxygen cutting, and deeper into the material for nitrogen cutting of thick stainless.
- Piercing. Before each contour the beam dwells to pierce through. Pierce time grows sharply with thickness and is a meaningful share of cycle time on plate, which is why a nest with many small holes costs more than its cut length suggests.
- Assist gas selection. Oxygen is used on mild steel, where the exothermic reaction with iron adds energy and roughly doubles achievable thickness — at the price of an oxide layer on the cut face. Nitrogen is used on stainless and aluminum to blow the melt out without oxidation, giving a bright, weld-ready and paint-ready edge at higher gas cost and lower speed. Compressed air is common on thin material.
- Contour cutting. A capacitive height sensor holds nozzle standoff within a few thousandths of an inch while the head follows the profile. Sharp corners are slowed or looped to avoid dwelling and burning.
- Part removal. Parts drop to a slat bed or are held by micro-tabs and broken out. Small parts, thin webs and long thin strips are where nesting problems appear.
- Secondary work. Dross removal or edge deburring where required, then forming, welding or finishing. Oxygen-cut mild steel needs the oxide layer removed before painting or welding.
Design guidelines
Minimum hole diameter
Keep holes at least 1× material thickness in mild steel and 1.5× thickness in stainless and aluminum. Smaller holes taper badly and the pierce disturbs the edge, because the beam has to blow through the full thickness in a spot barely larger than itself.
Minimum slot width and web
Slots should be at least 1× material thickness wide, and the web left between two cutouts or between a cutout and the edge should also be at least 1× thickness. Narrower webs overheat, warp and can burn through, especially in stainless.
Corner radii
Internal corners pick up the kerf radius automatically, roughly 0.005 in (0.13 mm). On plate, add a radius of at least half the material thickness to sharp internal corners so the head does not dwell in the corner and burn it.
Design for the bend, not just the cut
If the part will be formed, add bend reliefs at the ends of bend lines and keep holes at least 1.5× material thickness plus the bend radius away from the bend, or they will distort. See the bend radius and K-factor chart and specify stock from the sheet metal gauge chart.
Specify the edge condition you need
Nitrogen-cut stainless and aluminum come off bright, oxide-free and ready to weld or paint. Oxygen-cut mild steel carries an oxide layer that must be removed first. Thermal cut quality is classified by ISO 9013 (perpendicularity tolerance and mean height of profile), which is the right language for a drawing note.
Know what must not go in the machine
PVC and other chlorinated plastics release hydrogen chloride when lasered — toxic to operators and corrosive to the machine — and no reputable shop will run them. Polycarbonate burns and discolors rather than cutting cleanly. Galvanized and coated steels cut but require zinc fume extraction.
| Material | Machine / gas | Practical limit and notes |
|---|---|---|
| Mild steel | Fiber, oxygen | ~1 in (25 mm) at 4–6 kW; oxide edge needs removal before paint or weld |
| Stainless steel | Fiber, nitrogen | ~1 in (25 mm) at high power; bright oxide-free edge |
| Aluminum | Fiber, nitrogen | ~0.5–0.75 in (12–19 mm); reflective, prone to dross |
| Brass, copper | Fiber | Thin sections; highly reflective, needs back-reflection protection |
| Titanium | Fiber, argon | Argon shielding prevents a brittle oxidized edge |
| Acrylic (PMMA) | CO2 | Flame-polished transparent edge; the showcase laser material |
| Plywood, MDF, leather | CO2 | Charred edge, extraction required |
| Polycarbonate | Poor | Burns and yellows; mechanical cutting is better |
| PVC, vinyl, PTFE | Never | Releases hydrogen chloride or fluorine compounds |
| Feature | Recommended | Limit | Why |
|---|---|---|---|
| Hole diameter | ≥ 1.5× thickness | 1× thickness (mild steel) | Small holes taper and blow out on pierce |
| Slot width | ≥ 1× thickness | 0.8× thickness | Kerf and heat need room |
| Web between features | ≥ 1× thickness | 0.8× thickness | Thin webs overheat and warp |
| Internal corner radius | ≥ 0.5× thickness | Kerf radius, ~0.005 in | Prevents corner burn on plate |
| Hole to bend line | ≥ 1.5× thickness + bend radius | — | Holes distort inside the bend zone |
| Tab / thin strip width | ≥ 2× thickness | 1× thickness | Thin strips warp from heat |
Cost drivers
Laser cutting carries no tooling cost, so price is machine time plus material, and machine time is dominated by two things: how far the head travels and how many times it has to pierce.
Cut length and pierce count. A part with fifty small holes may take longer than a part twice its size with none. Every hole is a pierce plus a contour.
Thickness. Speed falls steeply with thickness while pierce time climbs. Doubling plate thickness costs far more than double the time.
Material and assist gas. Nitrogen cutting consumes large volumes of gas and runs slower than oxygen cutting; a bright oxide-free edge on stainless is a real premium over an oxide edge on mild steel.
Nesting efficiency. You pay for the sheet, not the part. A shape that nests tightly, or that can share cut lines with its neighbor, can shift material cost noticeably. Ask the shop to nest before finalizing the outline.
Setup and programming. Small, but it is why a single piece costs more per part than fifty of the same piece off one sheet.
Four ways to take cost out:
- Consolidate or enlarge small holes — hole count drives pierce count, which drives cycle time.
- Choose the thinnest gauge that meets the structural need (sheet metal gauge chart).
- Accept an oxygen-cut oxide edge on mild steel wherever the part will be blasted or coated anyway.
- Design outlines that tile: rectangles and shapes with parallel edges nest tighter than free-form profiles.
Questions
7 questionsHow thick a material can a laser cut?
A 4–6 kW fiber laser cuts mild steel to about 1 in (25 mm) with oxygen assist, stainless to roughly the same with nitrogen at high power, and aluminum to about 0.5–0.75 in (12–19 mm). Machines at 10–20 kW extend mild steel to roughly 1.5 in (38 mm). Above that, plasma or water jet cutting is faster and cheaper.
What tolerance does laser cutting hold?
±0.005 in (±0.13 mm) on thin sheet is normal, opening to ±0.010 in (±0.25 mm) on plate and across long dimensions. The cut face also carries about 0.5–1° of taper, which matters when the edge is a mating surface rather than a free profile.
What is the minimum hole size for laser cutting?
About 1× material thickness in mild steel and 1.5× thickness in stainless and aluminum. Below that the pierce disturbs the edge and the hole comes out tapered, because the beam must blow through the full thickness in a spot barely wider than the kerf. Smaller holes should be drilled or punched afterward.
What is the difference between a fiber laser and a CO2 laser?
A fiber laser emits at 1.06 µm, which metals absorb efficiently, so it cuts steel, stainless, aluminum, brass and copper faster and with lower running cost. A CO2 laser emits at 10.6 µm, which organics absorb well, making it the machine for acrylic, plywood, MDF, leather and paper. Fiber lasers cut clear acrylic poorly because the material is largely transparent at that wavelength.
Which materials should never be laser cut?
PVC and other chlorinated plastics, including vinyl, release hydrogen chloride gas that is toxic to operators and corrodes the machine. PTFE releases fluorine compounds. Polycarbonate burns and yellows instead of cutting cleanly. Galvanized and coated steel can be cut but requires zinc fume extraction.
Does laser cutting leave a heat affected zone?
Yes — it is a thermal process, so a narrow zone along the cut face is heated and rapidly cooled, typically a few thousandths of an inch on sheet and wider on plate. It is small enough to ignore for most fabrication, but for hardened, tempered or fatigue-critical parts, water jet cutting removes the question entirely because it produces no heat affected zone.
Should I use oxygen or nitrogen assist gas?
Oxygen on mild steel, where the exothermic reaction with iron adds energy and roughly doubles the thickness the machine can handle, leaving an oxide layer that must be removed before painting or welding. Nitrogen on stainless and aluminum, which blows the melt out without oxidation and leaves a bright edge ready to weld or paint, at higher gas cost and lower speed.