1. CO₂ Laser Cutting (Traditional Technology)
With oxygen as assist gas (enhances combustion to improve cutting efficiency): The maximum cuttable thickness is 25–30 mm (using a 6000–8000 W CO₂ laser).
With nitrogen as assist gas (for oxide-free, high-quality edges): The maximum thickness is reduced to 15–20 mm (same laser power range), as nitrogen only serves as a shielding gas and does not assist with material removal.
2. Fiber Laser Cutting (Mainstream High-Efficiency Technology)
With oxygen assist gas: A 12000 W fiber laser can cut Q355NH plates up to 40–45 mm thick; a 20000 W high-power fiber laser can reach 60–80 mm (for heavy industrial applications).
With nitrogen assist gas: A 12000 W fiber laser can handle up to 25–30 mm thickness, producing clean, rust-resistant edges without secondary grinding.
3. Key Notes for Thick Plate Laser Cutting
Cutting Speed Trade-off: Thicker plates require lower cutting speeds to ensure full penetration. For example, a 40 mm Q355NH plate cut with a 12000 W fiber laser and oxygen assist gas has a speed of only 0.1–0.3 m/min.
Edge Quality: Thick plates cut with oxygen may have a thin oxide layer on the edges, which can be removed by light grinding. Nitrogen cutting avoids this but costs more due to higher gas consumption.
Patina Impact: For pre-patinated Q355NH plates, high heat during thick plate cutting may cause localized patina peeling near the cut edges-apply a patina accelerator post-cutting to restore uniformity.
