Laser cutting separates sheet metal by focusing a high-intensity beam onto the surface, heating the metal to its melting or vaporization point while a high-pressure assist gas blows the molten material out of the cut. There is no tooling to build, no contact force on the part, and the cut path is driven straight from the CAD geometry, which is why a laser is the default first operation for precision sheet-metal work. The variables that actually decide whether a part runs clean are the laser type, the available power against the material thickness, the assist gas, and how features are spaced for the kerf and the heat-affected zone. (EVS Metal, CO2 vs. Fiber Lasers)

This guide covers the working numbers a designer or buyer needs: fiber versus CO2 laser behavior, maximum cut thickness by material and laser power, kerf width and dimensional tolerance, assist gas selection by material, minimum hole and feature size, and how laser cutting compares to punching. Every figure below is tied to a published source.

Fiber vs CO2: Two Ways to Make the Beam

Both laser types do the same job, focus light energy to melt or vaporize metal, but they generate and deliver that energy differently, and the difference drives real performance gaps. A CO2 laser excites a carbon-dioxide gas mixture in a resonator and routes the beam through mirrors to the cutting head, producing infrared light at a 10.6-micron wavelength. A fiber laser pumps laser diodes that excite a rare-earth-doped (typically ytterbium) optical fiber, amplifying the light inside the fiber and delivering it through a fiber-optic cable, at a 1.06-micron wavelength, roughly ten times shorter than CO2. (EVS Metal)

That shorter wavelength is the whole story. Metal absorbs 1.06-micron light far better than 10.6-micron light, so a fiber laser is more electrically efficient, cuts thin-to-medium material faster, and, critically, cuts highly reflective metals like copper, brass, and aluminum that historically gave CO2 systems trouble. CO2 retains an edge in two places: it cuts non-metals (acrylic, wood, many plastics) that fiber wavelengths barely absorb, and on thick mild steel it can produce a slightly smoother edge. (EVS Metal)

The speed gap is largest on thin gauge and closes as material gets thicker. One published comparison puts a fiber laser at roughly 6 times the cutting speed of CO2 at 1 mm, narrowing to about 2 times faster at 5 mm. For the 0.5 mm to 6 mm range that covers most precision sheet-metal parts, that throughput advantage is why fiber has become the production standard. Atlas Manufacturing runs 4 kW and 6 kW Bystronic fiber lasers for exactly this reason: the bulk of fabricated sheet-metal work lives in the gauge range where fiber is fastest and cleanest.

Maximum Cut Thickness by Material and Power

The most common spec question is simply: will this machine cut my material at my thickness? Cut capability scales with laser power, and it drops sharply from carbon steel to stainless to aluminum, because the assist-gas chemistry and the metal’s reflectivity both work against the thicker, more reflective materials. The table below gives realistic industry-general maximums by fiber-laser power class. Atlas’s machines are 4 kW and 6 kW Bystronic fiber lasers, so the 3–4 kW and 6 kW rows bracket the power range Atlas actually runs.

One caveat that matters for procurement: maximum cut thickness is not the same as stable production thickness. A 6 kW machine can push through 25 mm carbon steel, but the speed is slow and the edge is rough at that limit. For clean, repeatable, economical cuts, shops run well below the maximum. When you ask whether a part is a good fit, the honest answer is framed around production-quality thickness, not the demo number. (GWEIKE)

Assist Gas: Oxygen, Nitrogen, or Air

The assist gas does two jobs: it blows molten metal out of the kerf, and on some materials it participates chemically in the cut. The gas choice changes both the achievable thickness and the edge quality, so it is part of the part spec, not an afterthought.

• Oxygen reacts exothermically with carbon steel, adding heat to the cut. It produces the thickest achievable cut on carbon steel, but leaves an oxide layer on the edge that may need removal before painting or welding.
• Nitrogen is inert; it shields the cut from oxidation and produces the cleanest, oxide-free edge. It is the standard choice for stainless steel and aluminum where a bright, weld-ready or paint-ready edge matters. It costs more and cuts thinner than oxygen on carbon steel.
• Compressed air is the lowest-cost gas and works on thinner material across all three metals, trading some edge quality for operating cost.

Kerf, Tolerance, and Edge Quality

The kerf is the narrow slot the beam burns away as it cuts. Kerf width depends on material type, thickness, laser power, and focus, and runs roughly 0.08 mm to 0.45 mm (about 0.003 in. to 0.018 in.) across typical sheet-metal materials and thicknesses. The kerf is why nested parts need a minimum gap between them: hold parts at least 1 mm to 2 mm apart to avoid accidental crossover cutting, and keep parts 2 mm to 5 mm in from the sheet edge, since stock can be warped or off-size at the perimeter. (Geomiq, Sheet Metal Design Guide (Kerf))

For dimensional tolerance, a representative published standard for laser-cut sheet metal holds linear dimensions (excluding bend locations) to +/- 0.1 mm (about +/- 0.004 in.), feature-to-feature on a flat blank to +/- 0.1 mm, and surface roughness in the area of +/- 3.2 micrometers. Bend-related tolerances are looser, around +/- 0.4 mm on formed dimensions and +/- 1 degree on bend angle, which is one reason flat-blank features are dimensioned independently of bends on a good print. (Geomiq, Tolerances)

Atlas’s numbers on its Bystronic machines: part dimensional tolerance of +/- 0.005 to +/- 0.010 in (+/- 0.125 to +/- 0.25 mm) depending on alloy, thickness, and geometry, with machine positioning accuracy of +/- 0.002 to +/- 0.005 in (+/- 0.05 to +/- 0.125 mm). Flag critical dimensions on the print so the cutting group can confirm them against the specific alloy and thickness at quote.

The cut edge has its own behavior. Laser cutting creates a small heat-affected zone (HAZ): a thin band near the cut where the rapid heat and resolidification locally hardens the edge. On carbon steel, higher hardenability means a larger HAZ. That localized hardening produces a durable, smooth edge that often needs no secondary finishing, but it matters if the edge will be tapped, formed tightly, or machined afterward. Distortion comes from the sudden temperature rise and rapid solidification at the cut zone, which is part of why thin parts and tight nests are sequenced to manage heat input. (Geomiq, Localized Hardening and Distortion)

Minimum Hole and Feature Size

Laser cutting can make very fine features, but the practical floor is tied to material thickness. The widely used design rule is to keep the smallest hole diameter at or above the material thickness. A hole much smaller than the sheet thickness is hard to cut cleanly and tends to leave a tapered or rough wall, because the beam has to dwell in a tiny area through the full thickness of the metal. The same logic governs narrow slots and thin web sections: as thickness goes up, the minimum clean feature size goes up with it. (Geomiq, Minimum Hole Diameter)

• Minimum hole diameter: at least equal to material thickness. For a 3 mm sheet, hold holes to 3 mm or larger for clean results.
• Part-to-part nesting gap: 1 mm to 2 mm minimum to prevent crossover cutting between adjacent parts.
• Part-to-sheet-edge margin: 2 mm to 5 mm, to stay clear of warped or off-size stock at the perimeter.
• Tabs and micro-joints: small uncut tabs left in the nest hold parts in the skeleton during cutting so they do not tip into the beam; they are snapped or trimmed out after cutting.

Material restrictions matter too. Mirrored or fully reflective surfaces, masonite, and PVC-containing composites are not suitable for laser cutting (PVC releases corrosive, toxic gas when lasered). Most metals, stainless, many aluminum thicknesses, and some woods and plastics cut well. (Geomiq, Material Restrictions)

Laser Cutting vs Punching

Laser cutting is not the only way to put holes and profiles in sheet. CNC punching shears holes and shapes with a punch and die, and for the right job it is faster and cheaper. The two processes are complementary, and a well-planned part often uses both.

• Laser wins on complex, arbitrary contours, tight inside corners, fine detail, one-off and low-volume work (no tooling), and reflective or thicker material where a fiber laser is well suited. The cut is non-contact, so there is no part distortion from punch force.
• Punching wins on high-volume repeated hole patterns, standard round and shaped holes that match available tooling, and formed features the laser cannot make at all, such as louvers, countersinks, extrusions, and dimples, which are formed by the punch and die. Punching leaves a characteristic edge: a rollover and burnished band on the punch-entry side, and a fracture zone with a burr on the die side.

The practical split: lasers handle the geometry and detail, punching handles volume hole patterns and formed-in features. For a deeper treatment of punch-to-die clearance, edge quality, and minimum punched-hole sizing, see the sheet metal punching guide.

Material Selection for Laser-Cut Parts

Material choice drives both cutting behavior and downstream performance. The laser-specific tradeoffs:

• Carbon / mild steel. Cuts thickest of the three with oxygen assist; lowest material cost. Needs a finish or coating for corrosion resistance, and the oxide edge from oxygen cutting may need cleanup before paint or weld.
• Stainless steel (304, 316). Cut with nitrogen for a bright, oxide-free edge. Corrosion-resistant and strong; thinner maximum cut thickness than carbon steel at the same power.
• Aluminum (5052, 6061). Reflective and thermally conductive, so it cuts thinner than steel and benefits from fiber's shorter wavelength. Cut with nitrogen for a clean edge. Light and corrosion-resistant.
• Copper and brass. Highly reflective; historically problematic for CO2 but reliably cut by fiber lasers thanks to better absorption at 1.06 microns.

For alloy-by-alloy property and specification data, consult mill data sheets and the relevant ASTM specifications, for example ASTM A1008 for cold-rolled carbon steel sheet, ASTM A240 for stainless steel sheet and plate, and ASTM B209 for aluminum sheet and plate, alongside the ASM Metals Handbook volume on machining and material processing.

Laser Cutting at Atlas Manufacturing

Atlas Manufacturing runs 4 kW and 6 kW Bystronic fiber lasers out of facilities in Minneapolis, Minnesota and Chippewa Falls, Wisconsin, serving engineers and procurement teams across telecom, medical device, industrial, and OEM markets. Cutting feeds directly into the rest of the shop: punching, forming, welding, powder coating, hardware insertion, and assembly under one roof.

The practical value to a design or buying team is catching fit and cost problems before the sheet is loaded: confirming the material and thickness sit in the production-quality range for the available power, picking the assist gas that gives the edge the next operation needs, and spacing holes and features for the kerf and HAZ. Send a print and the cutting group will flag thickness, feature-size, and material issues up front rather than at the machine.

Frequently Asked Questions