What the assist gas does
In laser cutting, the assist gas clears molten material from the kerf, cools the cut edge and shields the optics. Nitrogen gives the cleanest edge on stainless steel, but it is bought by the cylinder or the dewar and the cost scales directly with cutting hours. Compressed air is available on site and costs electricity instead, which is why many shops cut with air wherever the edge quality requirement allows it.
The pressure question
Air assist for fibre laser cutting typically sits in the 16 to 20 bar band, well above general workshop pressure. That is why laser packages are built as dedicated high pressure systems rather than tapped off the plant header: the whole plant does not need to run at 16 bar, and raising it would cost energy everywhere.
What the air has to be
| Requirement | Why it matters |
|---|---|
| Pressure stability | A pressure dip shows up as a rough cut or a dross edge; the laser's cut parameters assume a steady supply |
| Dryness | Moisture carries through the nozzle and can mark the cut edge and disturb the lens protection |
| No oil | Oil aerosol deposits on the protective window and the lens, which is a costly failure |
| Filtration | Particulate removal protects the nozzle and the optics from the compressed air side |
| Continuous duty | Cutting runs for hours; the compressor has to be rated for continuous operation at that pressure |
Sizing approach
Start from the cutting machine's specified air consumption at its working pressure - the laser builder quotes both. Add margin for nozzle variation and for the dryer and filter pressure drop, then size the compressor and receiver for that figure. Storage matters here: a receiver that carries the system through short demand spikes keeps the compressor from cycling at high pressure.
Total cost comparison
Air assist is not free; compressing to 16 bar takes real power, and the dryer and filters add a little more. The comparison is between that electricity bill and the delivered cost of nitrogen per hour of cutting. For shops cutting many hours a week, the air option usually wins on running cost - and the break-even depends on local electricity and gas prices, so it should be calculated rather than assumed.
Send us your working pressure, required flow and site conditions and we will propose a configuration. Contact OPPAIR.