Thick Plate Processing (20mm+)
High-power fiber lasers (12–30kW) have pushed the cutting frontier to 30mm+ in carbon steel and 50mm+ with oxygen assist. For structural fabricators, this means base plates, end plates, and heavy gussets can now be laser-cut with superior edge quality compared to flame or plasma.
Quick Answer
Laser cutting 20mm+ mild steel requires 12kW minimum (nitrogen) or 6kW minimum (oxygen). At 25mm, expect speeds of 0.5–1.5 m/min with N₂ and 0.8–1.8 m/min with O₂. Edge quality is ISO 9013 class 1–2, superior to plasma (class 2–3). The trade-off: higher gas consumption at thick sections makes O₂ assist more economical above 20mm, but produces oxidized edges requiring cleaning before welding.
Thick Plate Parameters
| Thickness | Gas | Min Power | Speed | Edge Quality | Notes |
|---|---|---|---|---|---|
| 20mm | N₂ 16 bar | 10kW | 0.8–1.5 m/min | ISO 9013 Class 1 | Oxide-free edge |
| 20mm | O₂ 3 bar | 6kW | 1.0–1.8 m/min | ISO 9013 Class 1–2 | Oxide layer, lower gas cost |
| 25mm | N₂ 18 bar | 15kW | 0.5–1.0 m/min | ISO 9013 Class 1–2 | High gas consumption |
| 30mm | O₂ 3–4 bar | 10kW | 0.6–1.2 m/min | ISO 9013 Class 2 | Economic for structural |
| 40mm | O₂ 4–5 bar | 15kW | 0.3–0.6 m/min | ISO 9013 Class 2–3 | Consider plasma >40mm |
Laser vs Plasma vs Flame: Thick Plate
| Factor | Fiber Laser | HD Plasma | Oxy-Fuel |
|---|---|---|---|
| Max thickness (carbon) | 30–50mm | 80mm+ | 300mm+ |
| Tolerance (at 25mm) | ±0.2mm | ±0.5mm | ±1.5mm |
| Edge quality (25mm) | ISO 9013 Class 1–2 | ISO 9013 Class 2–3 | ISO 9013 Class 3–4 |
| Speed (at 25mm) | 0.5–1.0 m/min | 1.0–2.5 m/min | 0.2–0.4 m/min |
| Small holes | Ø = 1× thickness | Ø = 1.5× thickness | Not practical |
| Operating cost /hr | $25–$45 | $15–$30 | $8–$15 |
Related Topics
Disclaimer: Parameters for thick plate are highly dependent on specific machine model, beam quality, and nozzle design. Values represent achievable ranges on current-generation equipment.