Contents
- Quick answer: how thick can a fiber laser cut?
- Reading a thickness chart by power and material
- Maximum severance versus production thickness
- How material changes thickness capacity
- How assist gas affects thickness and quality
- Starting the power discussion from routine thickness
- What affects usable cutting thickness?
- Turn thickness capacity into acceptable-part cost
- How to validate thickness before purchasing
- Comparing fiber laser, plasma and waterjet
- Frequently asked questions
- Conclusion: assess thickness, quality and workload together
Cutting thickness is often the first specification a buyer checks—and one of the easiest to misunderstand. Two 6kW machines may quote different mild-steel limits without contradicting each other: material, gas, head, test method and quality criteria may differ.
This guide considers power/material ranges, maximum severance, repeatable production and part quality together. Start with the main workload and validate it with actual material and parts rather than selecting the highest number in a chart.
1. Quick answer: how thick can a fiber laser cut?
There is no single answer independent of material and process. Suitable fiber-laser configurations handle both thin and thick work, but severing a test piece once is different from delivering acceptable parts every day. Rated power starts the comparison; it cannot replace configuration and sample acceptance.
Read three conditions alongside each figure: which material, which assist gas and which acceptance standard. Oxygen-cut mild steel and nitrogen-cut stainless figures are not interchangeable; copper, aluminum and steel do not share a thickness limit at the same power.
- Use maximum thickness for initial screening and production thickness for the daily operating range.
- Assess capacity alongside dross, squareness, hole quality and subsequent operations.
- Compare the same material, gas and parts, not only kW.
2. Reading a thickness chart by power and material
The table retains the supplied reference’s power groups; thicknesses are in mm. These are illustrative ranges, not GWMT ratings, available configurations or acceptance commitments. Each range needs a specific grade, source, head, gas and speed; the chart does not provide a complete test protocol.
Do not treat high-power maxima as routine production or assume every machine with that rating reaches the upper figure. The 20kW+ row is a discussion of higher-power systems, not an offered option on this page. Combined copper/brass ranges cannot replace alloy-specific validation.
- ¹ Confirm alloy, gas, reflection protection and approved process separately for copper and brass. This column does not specify gas; do not assume nitrogen.
- Ranges are neither continuous-production commitments nor limits for arbitrary sheet and contours.
- Request a report for the quoted complete machine under matching conditions, with thickness definition, quality and complete cycle.
| Optical power | Mild steel (O₂) | Stainless (N₂) | Aluminum (N₂) | Copper / brass¹ |
|---|---|---|---|---|
| 1kW | 6–10 | 3–5 | 2–3 | 2–3 |
| 1.5kW | 10–16 | 5–6 | 3–5 | 3–5 |
| 2kW | 14–20 | 6–8 | 5–8 | 4–6 |
| 3kW | 16–22 | 8–12 | 6–10 | 3–8 |
| 4kW | 20–25 | 10–12 | 8–12 | 5–8 |
| 6kW | 22–30 | 12–20 | 12–20 | 8–12 |
| 8–12kW | 25–40 | 20–30 | 18–30 | 12–20 |
| 20kW+ | 40–60+ | 30–50+ | 25–45 | System-dependent |
3. Maximum severance versus production thickness
The useful distinction is not the thickest sheet a machine has ever encountered but the range in which it makes acceptable parts reliably and economically. Define the meaning of each thickness figure in the inquiry and acceptance criteria, alongside speed and quality.
| Thickness category | What to evaluate |
|---|---|
| Maximum severance | Severance under favorable conditions; speed, piercing stability and edge quality may be limited. |
| Practical production thickness | Repeated conforming parts with acceptable intervention, scrap and cycle time. |
| Productive high-speed range | Speed and complete cycles support favorable unit cost while meeting quality. |
3.1 Maximum severance: screening, not production commitment
Near a severance limit, piercing can become more sensitive, speed can fall and dross, roughness or taper may increase. Small surface or batch differences matter more here. A successful single cut does not establish performance over an entire nest or repeated batches.
Use it to decide whether further investigation is worthwhile, not directly to calculate quotations, delivery or output.
3.2 Practical production: the repeatable daily range
Practical thickness is about stability: repeatable piercing, completed contours, acceptable holes and edges, and manageable manual intervention. Record full-sheet cycles, yield and postprocessing to translate thickness into usable output.
Prioritize this range for everyday purchasing rather than letting occasional maximum-thickness work dictate everything.
3.3 Productive thickness: better economics for routine orders
The productive range is not maximum travel speed. It is the range where acceptable quality and piercing, cutting, repositioning and handling produce favorable cycles. Many shops spend most cutting hours on thin or medium work; test that workload closely.
Evaluate efficiency by acceptable-part cost and compare subcontracting for rare extreme-thickness jobs rather than relying on advertised maxima.
4. How material changes thickness capacity
Materials differ in absorption, reflection, heat conduction and melting behavior, so identical power does not mean identical process windows. Grade, surface condition and later welding or finishing influence gas selection and edge assessment.
4.1 Mild steel
In oxygen cutting of mild steel, oxidation adds process heat, which helps explain why some charts quote greater thickness than nitrogen-cut materials at the same power. The edge may be oxidized; evaluate cleaning requirements before welding, painting or powder coating.
Confirm the gas before comparing. Oxygen severance and nitrogen clean-edge production should not be ranked as equivalent figures.
4.2 Stainless steel
Nitrogen fusion cutting is commonly used for stainless parts requiring low-oxidation edges. It removes melt and protects the kerf without the additional heat of oxygen reaction, so oxygen-cut mild-steel ratings cannot simply be applied to stainless.
As thickness increases, check gas flow, pressure, purity, dross and edge quality together. Gas expenditure and cleanup affect complete part cost, not just cutting speed.
4.3 Aluminum
Aluminum’s reflection and heat conduction make results sensitive to alloy, flatness, surface condition, beam delivery and focus. Do not assume different alloys at the same thickness perform identically from one sample.
Record alloy, surface treatment, gas and acceptable burr; inspect distortion, holes and downstream work. Validate the purchased material rather than borrowing steel ratings.
4.4 Copper and brass
Copper and brass are not interchangeable. Reflective materials require compatible source, head and protection, with the machine maker’s approval for the alloy. Do not probe equipment limits with unapproved parameters.
If busbars or other copper components dominate the business, use their edges, holes and repeated-production reports as selection evidence. Steel trials cannot validate copper work.
5. How assist gas affects thickness and quality
Gas is part of the process, not merely a consumable. Changing gas on the same machine can change oxidation, speed, supply requirements and usable thickness. Include the gas strategy and downstream quality in the trial conditions.
5.1 Oxygen: capacity versus oxidized edges
Oxygen contributes reaction heat in mild steel without increasing rated optical output. Suitability depends on the edge and later operations; oxide removal may be needed for welding or coating requirements.
Record speed, oxide, bottom dross and cleanup cost, not just maximum penetration.
5.2 Nitrogen: clean edges and gas delivery
Nitrogen processes are often chosen to reduce edge oxidation. On thicker work, verify delivery at the cutting head against manufacturer requirements through design and measurement, not only bottle or inlet pressure.
A clean edge alone does not establish part acceptance; check burr, squareness, holes and complete cycles.
5.3 Compressed air: validate quality and running expenditure
Compressed air may suit some thin or medium jobs, but oxidation, color and finishing differ from nitrogen. A seemingly lower gas cost does not establish suitability for appearance-, corrosion- or coating-sensitive parts.
Confirm treatment, filtration, drying and delivery meet equipment requirements; include compressor energy, maintenance and postprocessing in cost. Use approved pressure, flow and nozzle settings, not generic values from this article.
6. Starting the power discussion from routine thickness
Group orders by material and thickness and identify where production hours are spent. The following screening groups identify candidates only. Without complete material conditions, the thickness column cannot be applied across materials or replace conforming sample reports.
Stable edges on routine material matter more than barely severing rare thick jobs. Multiple shifts require comparing complete nest cycles, handling and downstream constraints. If thick work is rare, compare subcontracting with machine investment.
- Which materials and thicknesses dominate annual cutting hours?
- What burr, roughness, taper and postprocessing does the customer allow?
- Can orders, handling and downstream operations use extra capacity?
- Is current subcontracted acceptable-part cost better than complete in-house cost?
| Typical thickness / job | Power to investigate | Example workload |
|---|---|---|
| 0.5–4, fine features | 1–2kW | Enclosures, brackets, signs and thin-sheet prototypes |
| 3–10 | 3–4kW | Routine sheet metal and mixed orders |
| 6–16 | 6kW | Structural parts, machine components and medium plate |
| 12–25 | 8–12kW | Thicker-plate-focused production |
| Daily 20+ | 20kW+ | Dedicated thick-plate work; assess the full system separately |
7. What affects usable cutting thickness?
Power, speed, focus, nozzle and machine stability interact with material and gas. Changing one setting alone may not widen the acceptable production range. Retain parameter revisions and sample results rather than combining separate best figures into a nonexistent operating point.
7.1 Power: more margin, not twice the thickness
More power can improve piercing, speed or process margin on particular materials, but benefits are not linear. Heat flow, reflection and melt removal constrain results; moving from 3kW to 6kW does not establish doubled thickness or conforming output.
7.2 Grade and surface condition
Grade, alloy content, scale, coating, oil and flatness can change piercing and edges. Include actual incoming batches rather than treating specially prepared clean, flat samples as all production material.
7.3 Speed: evaluate within the quality window
Excessive speed can leave incomplete cuts and dross; too little speed may increase heat input, kerf width or thermal effects. Do not keep reducing speed only to reach a thickness figure; record whether the cycle and quality remain acceptable.
7.4 Gas pressure and flow at the head
Melt removal needs appropriate delivery. Pipework, regulation, filtration, nozzle and inadequate flow can limit thick work; correct inlet pressure does not establish working flow at the head. Qualified personnel should verify manufacturer requirements.
7.5 Focus and nozzle: separate thin and thick conditions
Focus, nozzle diameter, centering, gap and height-following stability affect beam and gas delivery into the kerf. Misalignment or wear can reduce process margin. Use validated recipes and approved maintenance/calibration procedures.
7.6 Source, head and complete-machine compatibility
Beam quality, focus range, head power rating, reflection protection and thermal stability cannot be inferred from a source nameplate alone. Long thick-plate runs also require checking rigidity, motion and cooling. Compare complete systems rather than isolated sources.
8. Turn thickness capacity into acceptable-part cost
Thickness indicates feasibility; acceptable-part cost determines whether in-house work is worthwhile. Include piercing, cutting, repositioning, handling, waiting and required finishing, not merely speed on a long straight line. Near the limit, slow cycles, intervention and scrap can raise costs together.
One accounting method is occupancy rate × occupied time, plus energy, gas, consumables, labor, finishing and scrap not already included in that rate, allocated over acceptable output. Do not charge an item twice if included in the hourly rate; account for material yield separately.
Compare complete quotations and trial records for the same part, including yield, oxide removal, deburring and downstream requirements. Faster cutting need not mean lower cost; a better edge may also reduce later work.
9. How to validate thickness before purchasing
Actual material, actual drawings and repeated trials are stronger evidence than a published maximum. Give candidates the same job pack so differences reflect equipment and process rather than different stock or acceptance standards.
A single severed line is not enough. Include nesting, contours, small holes, extended runs and jobs near the intended production limit; record piercing failures, dross, distortion and intervention. Trial arrangements and final acceptance scope require separate agreement.
- Provide DXF or approved drawings, grade, thickness, surface condition and batch size.
- Agree burr, edge, dimensions, holes and downstream acceptance criteria beforehand.
- Record complete configuration, optical power, gas purity/delivery, nozzle, focus, piercing and cutting conditions.
- Check repeated parts and full-sheet results; retain cycles, yield, samples and report revisions.
10. Comparing fiber laser, plasma and waterjet
Fiber laser is not the lowest-cost answer to every thick-plate job. Compare material, contour, precision, thermal effects and volume. Very thick conductive stock, heat-sensitive material or parts already requiring substantial machining may justify another process.
The table compares process characteristics, not universal maxima or cost rankings. The particular equipment, part and acceptance criteria determine suitability and economics.
- Plasma is not automatically cheapest; include precision, finishing and acceptable output.
- Waterjet avoids laser thermal cutting but is not free of machining risks or finishing needs.
- For routine sheet metal compare laser first, and investigate alternatives for extreme thickness based on quality and cost.
| Process | Work to investigate | Thickness emphasis | Strengths and limits |
|---|---|---|---|
| Fiber laser | Metal sheet/plate and detailed contours | Thin to thicker work, configuration-dependent | Fine kerf and productivity; assess heat, gas and quality |
| Plasma | Conductive material and thicker structural work | Medium to very thick, system-dependent | May suit some thick jobs economically; check kerf, edge and precision |
| Waterjet | Heat-sensitive and mixed-material work | Broad range, material/system-dependent | Avoids thermal cutting; assess speed, taper, abrasive and finish |
11. Frequently asked questions
These answers explain how to use thickness information; they do not certify a machine. Use traceable trials and an agreed written scope for the particular material and configuration.
- What is the actual fiber-laser thickness limit?
It depends on material, power, gas, complete configuration and acceptance quality. The chart organizes screening questions but cannot establish a configuration’s capacity. Define severance, practical or productive thickness before comparing matching reports.
- How thick can 3kW cut?
The 3kW example lists mild steel/O₂ 16–22mm, stainless/N₂ 8–12mm, aluminum/N₂ 6–10mm and copper/brass 3–8mm. These are not GWMT ratings or production commitments; validate alloy, gas, edge and full cycle on actual parts.
- How thick can 6kW cut?
The 6kW example gives mild steel/O₂ 22–30mm, stainless/N₂ and aluminum/N₂ 12–20mm, and copper/brass 8–12mm, requiring configuration-specific trials. Compare 3kW and 6kW by acceptable output, piercing and cost on routine thickness, not only maxima.
- How thick can 12kW cut?
The reference combines 8–12kW: mild steel 25–40mm, stainless 20–30mm, aluminum 18–30mm and copper/brass 12–20mm. This is not a dedicated 12kW rating and does not imply equal 8kW/12kW performance; request the specific machine, gas and material report.
- Does doubling power double thickness?
No proportional conclusion follows. Heat transfer, reflection and melt removal differ by material and gas. Extra power may primarily improve speed or piercing on routine work rather than scale maximum thickness. Compare measured cycles and quality for the same part.
- Why do thickness charts disagree?
Charts may use different grades, gas, sources, heads, focus, nozzles, speeds and quality criteria, or describe severance versus repeatable production. Check definitions and conditions first; without them, figures cannot be ranked directly.
12. Conclusion: assess thickness, quality and workload together
Thickness capacity is a system result, not an independent property of source power. Power provides part of the process conditions; material, gas, focus, nozzle, piercing and machine stability determine the capacity usable for conforming production.
Define quality first, cover primary materials and thicknesses, then validate complete cycles, yield and finishing with your drawings and stock. Keep severance distinct from production thickness and compare cost per acceptable part to establish the equipment scope for real orders.
- Treat charts as references, not contractual proof of capacity.
- Use the main workload to define material, thickness and parts for validation.
- Retain trial conditions, samples and reports for a reviewable comparison.
Technical references
Manufacturer references support process explanations; images illustrate selection topics, not an approved GWMT supply specification.