Table of Contents
Fiber laser cutting parameters are not a single table. They are a decision tree: material, thickness, and quality requirement determine gas type, which determines focus direction, which determines nozzle type — and only then do speed and pressure make sense. This guide walks through that decision tree first, then gives the complete validated data.
The tables below cover 500W to 60KW across four materials. If you run a 3KW system cutting 6mm carbon steel daily, you need three rows of data. If you are specifying a new machine to cut 25mm plate, you need the power selection logic first. Both are here.
Five Parameters That Control Every Cut
Every row in the tables below is defined by the same five variables. Understanding what each one does — not just its value — lets you diagnose problems and make confident adjustments when a table value doesn't quite match your result.
Cutting speed (m/min)
Speed controls how long the laser dwells on each point of material. Too fast and you get incomplete cuts or heavy dross at the bottom. Too slow and you get excessive melting, wide kerf, and heat-affected zone damage. The tables show ranges (e.g., 3.5–4.2 m/min) — the lower end suits thicker or less-than-ideal surface conditions, the upper end suits clean, flat material with good fit-up.
Laser power (W)
Power sets the energy ceiling. For most entries in this guide, the machine runs at the rated power level — cutting is a continuous-wave process unlike welding, which uses peak power percentages. Where a value lower than the rated power appears (common in 3KW sheets where some entries show 2100W or 2400W), it means the optimal cut quality comes from slightly throttled power rather than running full output.
Assist gas type and pressure (bar)
Gas does two jobs: it blows molten material out of the kerf, and (in the case of oxygen) it drives an exothermic oxidation reaction that adds cutting energy. Gas choice is the most consequential parameter decision — it determines focus direction, nozzle type, and the entire operating window. See Section 2 for the full decision logic.
Focus position (mm)
Focus position sets where the beam waist sits relative to the material surface. Zero means the waist is exactly at the surface. Positive values put the waist above the surface (beam is diverging when it hits the material). Negative values put the waist below the surface (beam is still converging). Critically, the correct direction differs by material and gas type — see Section 5.
Nozzle type and diameter (mm)
The nozzle shapes the gas flow over the cut zone. Diameter and type must match the gas pressure and material thickness — an undersized nozzle on thick plate starves the kerf of shielding gas; an oversized nozzle wastes gas and can destabilize the flow pattern. Five nozzle families are used across the 500W–60KW range; see Section 6.
Gas Selection: Three Strategies
Before looking up any other parameter, choose the gas strategy that matches your material and priority. This single decision determines focus direction, nozzle family, speed range, and cut quality outcome.
N₂ / Air — thin carbon steel, speed priority
- Materials Carbon steel 1–3mm
- Gas N₂ or compressed air
- Pressure 10–14 bar
- Focus 0 to –1mm
- Nozzle Single (S), small diameter
- Result Maximum speed, slight bottom dross
O₂ — thick carbon steel, quality priority
- Materials Carbon steel 2mm and above
- Gas Oxygen
- Pressure 0.5–1.6 bar (much lower!)
- Focus +3 to +14mm (positive)
- Nozzle Double (D) or E-type
- Result Clean cut face, lower speed than N₂ on thin
N₂ — stainless steel, aluminum, brass
- Materials All non-carbon metals
- Gas Nitrogen only
- Pressure 10–20 bar (increases with thickness)
- Focus 0 to –13mm (negative on thick)
- Nozzle Single (S) thin, Beam (B) thick high-power
- Result Oxide-free bright cut edge
Power Selection Guide
The right power level is the one that covers your maximum required thickness with enough margin that you are not running at the top of the operating window every day. A machine running at its maximum rated capacity for thick plate has no room to compensate for surface variation, focus drift, or lens contamination.
The table below shows the maximum validated cutting thickness at each power level for each material:
| Power | Carbon steel (mm) | Stainless steel (mm) | Aluminum (mm) | Brass (mm) |
|---|---|---|---|---|
| 500W | 6 | 3 | — | — |
| 1KW | 10 | 5 | 3 | 3 |
| 1.5KW | 16 | 6 | 4 | 3 |
| 2KW | 20 | 8 | 6 | 5 |
| 3KW | 22 | 10 | 8 | 6 |
| 4KW | 25 | 12 | 10 | 8 |
| 6KW | 25 | 20 | 16 | 12 |
| 8KW | 40 | 30 | 30 | 16 |
| 12KW | 40 | 40 | 40 | 16 |
| 20KW | 80 | 100 | 60 | 20 |
| 60KW | 200 | 150 | — | — |
Complete Parameter Tables
Tables are organized by material. Within each table, rows are sorted by thickness; power level columns show the range of validated speeds at each thickness. Where a range is shown (e.g., 3.5–4.2 m/min), start at the midpoint and adjust based on cut quality.
| Thickness | 500W | 1KW | 1.5KW | 2KW | 3KW | 4KW | 6KW | 12KW | Nozzle | Pressure |
|---|---|---|---|---|---|---|---|---|---|---|
| 0.8mm | 12 | 18 | — | — | — | — | — | — | 1.5S | 10 bar |
| 1mm | 10 | 10 | 20 | 25 | 28–35 | 28–35 | 35–45 | 50–60 | 1.5S | 10–12 bar |
| 2mm | — | — | — | 9 | 16–20 | 12–15 | 20–25 | 35–40 | 2.0S | 10–12 bar |
| 3mm | — | — | — | — | — | 8–12 | 12–14 | 28–33 | 2.0S | 13–14 bar |
| 4mm | — | — | — | — | — | — | 8–10 | 20–24 | 2.0–2.5S | 13 bar |
| 5mm | — | — | — | — | — | — | 6–7 | 15–18 | 2.5–3.0S | 13 bar |
| 6mm | — | — | — | — | — | — | 5–6 | 10–13 | 3.0–3.5S | 13–16 bar |
Focus position: 0 to –1mm for all N₂/Air entries. Nozzle height: 0.5–1mm. Speed in m/min.
| Thickness | 1KW | 1.5KW | 2KW | 3KW | 4KW | 6KW | 12KW | Focus | Nozzle |
|---|---|---|---|---|---|---|---|---|---|
| 2mm | 4.0 | 5.0 | 5.2 | 3.8–4.2 | — | — | — | +3mm | 1.0–1.2D |
| 3mm | 3.0 | 3.6 | 4.2 | 3.2–3.6 | 4.0–4.5 | 3.5–4.2 | — | +3–4mm | 1.0–1.2D |
| 4mm | 2.3 | 2.5 | 3.0 | 3.0–3.2 | 3.0–3.5 | 3.3–3.8 | — | +3–4mm | 1.0–1.2D |
| 5mm | 1.8 | 1.8 | 2.2 | 2.7–3.0 | 2.5–3.0 | 3.0–3.6 | — | +4mm | 1.2D |
| 6mm | 1.5 | 1.4 | 1.8 | 2.2–2.5 | 2.5–2.8 | 2.7–3.2 | — | +4mm | 1.2–1.5D/E |
| 8mm | 1.1 | 1.2 | 1.3 | 1.8–2.2 | 2.0–2.3 | 2.2–2.5 | — | +4mm | 1.2–2.0D/E |
| 10mm | 0.8 | 1.0 | 1.1 | 1.0–1.3 | 1.8–2.0 | 2.0–2.3 | 2.0–2.3 | +3–4mm | 2.0D/1.2E |
| 12mm | — | 0.8 | 0.9 | 0.9–1.0 | 1.0–1.2 | 1.9–2.1 | 3.0–3.5 | +3–5mm | 3.0D/1.2E |
| 16mm | — | 0.5 | 0.7 | 0.6–0.7 | 0.7–0.9 | 1.2–1.4 | 2.8–3.0 | +3–6mm | 3.0–4.0D/E |
| 20mm | — | — | 0.4 | 0.5–0.55 | 0.55–0.65 | 0.6–0.7 | 1.5–1.6 | +3–8mm | 4.0D/1.6E |
| 25mm | — | — | — | — | 0.5 | 0.4–0.5 | 0.8–1.0 | +3–11mm | 5.0D/1.8E |
O₂ pressure: 0.5–0.7 bar for most entries, rising to 1.0–1.5 bar for 25mm+. Speed in m/min. O₂ cutting not recommended for 1mm or thinner — use N₂/Air instead.
| Thickness | 500W | 1KW | 1.5KW | 2KW | 3KW | 6KW | 12KW | Focus | Nozzle |
|---|---|---|---|---|---|---|---|---|---|
| 0.5mm | 24 | — | — | — | — | — | — | 0 | 1.5S |
| 1mm | 12 | 13 | 20 | 28 | 28–35 | 40–50 | 50–60 | 0 | 1.5S |
| 2mm | 2.7 | 6 | 7 | 10 | 18–24 | 25–30 | 40–45 | –1mm | 2.0S |
| 3mm | 0.7 | 3 | 4.5 | 5 | 7–10 | 15–18 | 30–35 | –1.5mm | 2.0–2.5S |
| 4mm | — | 1 | — | 3 | 5–6.5 | 10–12 | 22–26 | –2mm | 2.5S |
| 5mm | — | 0.6 | 1.5 | 2 | 3.0–3.6 | 7–8 | 15–18 | –2.5mm | 2.5–3.0S |
| 6mm | — | — | 0.8 | 1.5 | 2.0–2.7 | 6–7 | 13–15 | –3mm | 3.0S / 3.5B |
| 8mm | — | — | — | 0.6 | 1.0–1.2 | 3.5–3.8 | 8–10 | –4mm | 3.5S / 5.0B |
| 10mm | — | — | — | — | 0.5–0.6 | 1.6–2.0 | 6.5–7.5 | –6mm | 4.0S / 5.0B |
| 12mm | — | — | — | — | — | 1.0–1.2 | 5.0–5.5 | –7.5mm | 6.0B |
| 16mm | — | — | — | — | — | 0.5–0.6 | 2.0–2.3 | –10.5mm | 7.0B |
| 20mm | — | — | — | — | — | 0.2–0.35 | 1.2–1.4 | –11–12mm | 7.0B |
N₂ pressure: 10–12 bar for thin sheet, increasing to 16–20 bar for thick sections. Speed in m/min. Focus becomes increasingly negative as thickness grows — see Section 5 for the explanation.
| Thickness | 1KW | 1.5KW | 2KW | 3KW | 4KW | 6KW | 12KW | Focus | Nozzle |
|---|---|---|---|---|---|---|---|---|---|
| 0.8mm | 18 | — | — | — | — | — | — | 0 | 1.5S |
| 1mm | 10 | 18 | 20 | 25–30 | 25–30 | 30–45 | 45–50 | 0 | 1.5S |
| 2mm | 5 | 6 | 10 | 15–18 | 12–15 | 20–25 | 35–40 | –1mm | 2.0S |
| 3mm | 1.5 | 2.5 | 4 | 7–8 | 6–7 | 14–16 | 25–30 | –1.5mm | 2.0–2.5S |
| 4mm | — | 0.8 | 1.5 | 5–6 | 4–5 | 8–10 | 20–24 | –2mm | 2.5S |
| 5mm | — | — | 0.9 | 2.5–3 | 2.5–3 | 5–6 | 15–18 | –2.5–3mm | 3.0S |
| 6mm | — | — | 0.6 | 1.5–2 | 1.8–2.2 | 3.5–4 | 12–15 | –3mm | 3.0S |
| 8mm | — | — | — | 0.6–0.7 | 0.8–1.0 | 1.5–2 | 8–10 | –4mm | 3.0–3.5S |
| 10mm | — | — | — | — | 0.5–0.6 | 1.0–1.2 | 6–7 | –4.5mm | 3.5S |
| 14mm | — | — | — | — | — | 0.4–0.6 | — | –5mm | 4.0S |
| 16mm | — | — | — | — | — | 0.3–0.4 | — | –8mm | 5.0S |
N₂ pressure: 12 bar thin, increasing to 18–20 bar for 10mm+. Speed in m/min. Aluminum reflects significantly more near-IR energy than steel — ensure the cutting head has anti-reflective protection before cutting thick aluminum.
| Thickness | 1KW | 1.5KW | 2KW | 3KW | 4KW | 6KW | Focus | Nozzle |
|---|---|---|---|---|---|---|---|---|
| 1mm | 9 | 15 | 18 | 20–28 | 20–28 | 30–40 | 0 | 1.5–2.0S |
| 2mm | 2 | 5 | 8 | 10–15 | 10–14 | 18–20 | –1mm | 2.0S |
| 3mm | 0.8 | 1.8 | 3 | 5–6 | 5–6 | 12–14 | –1.5mm | 2.5S |
| 4mm | — | — | 1.3 | 2.5–3 | 2.5–3 | 8–9 | –2mm | 3.0S |
| 5mm | — | — | 0.8 | 1.8–2.2 | 1.8–2 | 5–5.5 | –2.5mm | 3.0S |
| 6mm | — | — | — | 0.8–1 | 0.8–1 | 3.2–3.8 | –3mm | 3.0S |
| 8mm | — | — | — | — | 0.5–0.6 | 1.5–1.8 | –3mm | 3.5S |
| 10mm | — | — | — | — | — | 0.8–1.0 | –3mm | 3.5S |
N₂ pressure: 12–16 bar. Speed in m/min. Brass is available in the 1KW–6KW range only — high-power cutting data for brass above 6KW is not included in this guide as applications are less common. Contact GWEIKE for specific requirements.
Focus Position Explained
Focus position is the parameter most operators either ignore or misunderstand. It does not change smoothly with material thickness — its behavior depends entirely on which gas strategy you are using, and for stainless steel and carbon steel it goes in opposite directions.
Carbon steel — O₂ cutting
Focus sits above the material surface and increases with thickness. At 6KW cutting 25mm carbon steel, focus reaches +14mm. On ultra-high-power systems (60KW, 100mm+), focus reaches +45mm. Reason: raising focus above the surface widens the beam footprint on the kerf entry, creating a bell-mouth profile that allows oxidation gas and combustion products to flow out of the cut channel without back-pressure stall. Positive focus also reduces the risk of the oxygen stream extinguishing itself in the narrow kerf of thick plate.
Stainless steel — N₂ cutting
Focus moves progressively below the surface as thickness increases — to –6mm at 10mm, –12mm at 20mm, –13mm at 25mm (12KW). Reason: nitrogen does not assist the cut chemically; it works purely by momentum, blasting molten metal out of the kerf bottom. The high-pressure N₂ jet must maintain its coherence all the way to the bottom of the cut. Negative focus positions the beam waist deep inside the material, keeping energy density high throughout the full kerf depth and preventing the top-rounded, bottom-widened kerf profile that appears when focus is set too high on thick N₂ cuts.
Nozzle Type Selection
Five nozzle families are used across the 500W–60KW range. The nozzle must match the gas type and material thickness — the wrong nozzle creates turbulent gas flow that destabilizes the cut, especially on thick sections.
High-Power Dual-Mode Strategy (≥6KW)
At 6KW and above, the parameter tables for carbon steel contain two parallel data sets for thicker sections — one for N₂/Air and one for O₂. This is not a duplication. They represent genuinely different operating strategies that produce different outcomes, and choosing between them is a production decision, not a parameter lookup.
Mode A: N₂ / Air high-speed (thin to mid plate)
Use when throughput is the primary driver and the application tolerates light dross on the bottom edge. Typical for sheet metal fabrication, enclosures, and structural work where the cut edge will be welded, ground, or bent. No oxygen means no combustion reaction — the cut is purely mechanical, driven by the high-pressure gas jet stripping molten material.
Mode B: O₂ positive focus (thick plate, quality priority)
Use when cut-face quality, dross-free edges, or maximum thickness is required. The oxygen exothermic reaction adds significant cutting energy — this is why O₂ pressure is dramatically lower than N₂ (0.6 bar vs 12 bar). Too much oxygen pressure at thick sections quenches the reaction; too little and penetration stalls. The 3-stage pierce sequence (Section 8) is required before every cut start on plate above 10mm.
Pierce Parameters for Thick Plate
When cutting thick carbon steel or stainless with oxygen, the machine cannot simply switch on and begin moving — the laser must first burn through the full plate thickness at a stationary point before the cut starts moving. This pierce sequence uses three power levels in sequence: high power initiates the plasma channel, then progressively lower settings stabilize it before the cut begins. Getting pierce parameters wrong is the most common cause of failed cut starts on heavy plate.
Three-stage pierce sequence
Each pierce uses three stages: High order (maximum power, starts the plasma), Median (reduced power and duty cycle, stabilizes the channel), Low order (minimum stable power, establishes the cut-start condition). The machine dwells at each stage for the specified time before advancing to the next.
| Stage | Power (W) | Duty (%) | Freq. (Hz) | Nozzle height | Gas pressure | Focus | Dwell time |
|---|---|---|---|---|---|---|---|
| High order | Example: 3KW O₂ pierce for 22mm carbon steel | ||||||
| 3000 | 100% | 200 Hz | 12mm | 1.0 bar | 0 | 200ms + 200ms purge | |
| Median | 3000 | 45% | 150 Hz | 8mm | 0.7 bar | –4mm | 2500ms + 200ms purge |
| Low order | 3000 | 55% | 150 Hz | 4mm | 0.6 bar | –6mm | 3000ms |
Troubleshooting
Heavy dross / slag on the bottom edge (carbon steel O₂)
Cause: Cutting speed too high for the thickness at this power, O₂ pressure too low, focus position too negative (beam waist too deep), or nozzle partially blocked.
Fix: Reduce speed by 5–8%. Verify O₂ pressure is 0.5–0.7 bar (very low pressures are correct for O₂ — do not increase above 1 bar for standard cutting). Confirm focus is positive (+3 to +4mm for mid-range thicknesses). Inspect nozzle with a loupe — even a small nick on the nozzle tip creates asymmetric gas flow that causes one-sided dross.
Cut face oxidised / yellow-brown on stainless steel
Cause: N₂ purity below 99.99%, gas pressure too low, nozzle standoff too high (gas shield breaks before reaching the cut zone), or small air leak in the gas line.
Fix: Verify N₂ purity is 99.99% minimum — this is the most common cause and the cheapest to fix. Check nozzle standoff is 0.5mm and the height sensor is calibrated. Increase gas pressure by 1–2 bar. Inspect all gas line fittings with soapy water for leaks. On thick sections (>10mm), ensure you have the correct beam-type (B) nozzle — standard single nozzles cannot maintain gas coverage at depth.
Cut not penetrating / partial cuts on thick carbon steel O₂
Cause: Pierce sequence not completed before cut motion started, focus position not positive enough, O₂ pressure too high (quenches the reaction), or lens contaminated.
Fix: Verify the pierce sequence completes all three stages before the machine begins moving. Increase focus position by +1mm steps until penetration improves. If O₂ pressure is above 1 bar on material under 30mm, reduce it — excess oxygen pressure is a very common error because operators assume "more gas = better." Clean or replace the cutting lens; a contaminated lens absorbs energy and reduces peak intensity at the focus point significantly.
Inconsistent cut quality across a sheet (speed variation)
Cause: Warped or bowed plate varying the nozzle standoff, accumulation of cutting debris under the plate raising the surface level, or belt/rack wear causing mechanical speed inconsistency in the motion system.
Fix: Ensure the plate is flat on the cutting bed — bow of more than 1–2mm across a 1.5m span will cause systematic quality variation. Clean the cutting bed slats and remove debris buildup before cutting large sheets. On older machines, run a servo calibration check if speed-related quality variation follows a periodic pattern.
Validate parameters on your specific material and machine
The tables in this guide are validated on GWEIKE M-Series systems with standard factory optics and certified cutting gas. Parameters on machines with different focal length optics, non-standard nozzle configurations, or alternative gas suppliers may require adjustment. Our applications team can review your setup and recommend starting parameters for your exact configuration.
FAQ
What gas should I use for laser cutting carbon steel?
For 1–3mm carbon steel, nitrogen or compressed air gives faster cutting speed with minor bottom dross. For 2mm and above where cut quality is important, oxygen with positive focus (+3 to +5mm) produces a cleaner cut face. At 6KW and above, both modes are viable — choose N₂/Air for speed, O₂ for quality on thicker sections. Never use oxygen on stainless steel — it oxidises the cut edge and destroys the corrosion resistance.
Why does focus position go positive for thick carbon steel but negative for thick stainless?
The cutting mechanisms are fundamentally different. Oxygen cutting adds chemical energy through combustion — raising focus above the surface widens the kerf entry so combustion products can escape without stalling. Nitrogen cutting is purely mechanical — lowering focus below the surface keeps energy density high at depth so the high-pressure gas jet can maintain momentum to eject molten metal from the kerf bottom. Same machine, opposite directions, different physics.
What is the maximum thickness a fiber laser can cut?
At 1KW: 10mm carbon steel, 5mm stainless. At 6KW: 25mm carbon steel, 20mm stainless. At 12KW: 40mm for both. At 60KW using O₂ positive focus: 200mm carbon steel (0.15–0.25 m/min). Maximum thickness for aluminum is lower than steel at equivalent power — roughly 60–70% of the carbon steel maximum at the same power level.
What is the difference between D, E, and B nozzles?
D (double) nozzles are for oxygen cutting of carbon steel at lower power levels — they provide a coaxial oxygen stream with an outer shield. E nozzles are single-exit high-flow nozzles for oxygen cutting on 6KW+ systems. B (beam) nozzles are large-diameter nitrogen nozzles (3.5–10mm) for cutting thick stainless steel and aluminum — the large bore is needed to deliver enough nitrogen flow to eject molten material from deep kerfs at high pressure.
Why is oxygen pressure so much lower than nitrogen pressure in these tables?
For oxygen cutting, the cut energy comes partly from the laser and partly from the exothermic oxidation of iron. High oxygen pressure quenches this reaction by cooling the cut zone and blowing the reacting material away before it can add energy. Typical O₂ cutting pressure is 0.5–0.7 bar — if you increase it above 1 bar trying to "help" the cut, you will degrade cut quality. Nitrogen, which does not assist chemically, must be at high pressure (10–20 bar) purely to eject molten metal by momentum.
Do I need to change parameters when cutting different alloy grades of stainless steel?
For common austenitic grades (304, 316), the parameters in this guide apply directly. Duplex stainless steels (2205, 2507) typically require 5–10% lower speed due to their higher strength and different thermal conductivity. Martensitic or ferritic grades may benefit from slightly higher N₂ pressure on thick sections. If you regularly cut non-304/316 grades, run a short test matrix on offcuts before committing to production settings.
