Cutting stainless on a 12000 W machine, compressed air runs almost as fast as nitrogen:

Thickness Nitrogen Air
 6 mm 13 – 15 14 – 17 m/min
 8 mm 8 – 10 9 – 11
10 mm 6.5 – 7.5 7 – 8
12 mm 5 – 5.5 5.5 – 6
16 mm 2 – 2.3 2.2 – 2.4

Across this range air is not slower at all. At several points it is slightly ahead.

What this means for running cost

Bottled nitrogen is a recurring monthly cost. Compressed air is a one-time investment in a compressor plus drying and filtration, after which only electricity remains.

For a shop running stainless continuously on a high-power machine, that difference is worth recalculating.

Before you switch

  • The air must be dry and clean. Moisture and oil in the line ruin the cut edge and foul the protective lens. Drying and filtration of the right class is required.
  • Flow must be sufficient. A high-power machine consumes far more gas than a small one; an undersized compressor will lose pressure mid-cut.
  • Low-power machines do not show this effect. The table above is for a 12000 W machine. At 3000 W the gap between the two gases is much wider.
  • The edge is slightly different. For parts with high surface requirements, run a test cut and compare before deciding.
Laser power selection tool