Assist Gas Cost & Selection Guide
Choose the right assist gas for your application and optimize costs
Oxygen (Oâ‚‚)
Best For:
Mild steel, carbon steel
Advantages:
- 20-30% faster cutting
- Lower gas cost ($0.10-0.30/m³)
- Exothermic reaction adds heat
Disadvantages:
- Oxidized (black) edges
- Not suitable for stainless/aluminum
- Requires post-processing for painted parts
Nitrogen (Nâ‚‚)
Best For:
Stainless steel, aluminum, brass, copper
Advantages:
- Clean, oxide-free edges
- No post-processing needed
- Suitable for painted/coated parts
Disadvantages:
- Higher cost ($0.50-2.00/m³)
- 20-30% slower than Oâ‚‚
- High pressure required (12-20 bar)
Air (Compressed)
Best For:
Thin mild steel (<3mm), general purpose
Advantages:
- Lowest cost (compressor only)
- Suitable for non-critical parts
- No gas supply needed
Disadvantages:
- Limited thickness capability
- Moderate edge quality
- Requires oil-free compressor
Cost Comparison by Application
| Application | Recommended Gas | Cost per Hour | Notes |
|---|---|---|---|
| Mild Steel (structural) | Oxygen | $0.50-1.50 | Fastest, lowest cost |
| Mild Steel (for painting) | Nitrogen | $2.00-5.00 | Clean edges, no grinding |
| Stainless Steel | Nitrogen | $3.00-6.00 | Required for quality |
| Aluminum | Nitrogen | $2.50-5.00 | High pressure needed |
| Thin sheets (<3mm) | Air | $0.20-0.50 | Compressor cost only |
Costs assume bottled gas delivery. On-site generation reduces nitrogen cost by 50-70%.
On-Site Nitrogen Generation
When does it make sense to invest in your own nitrogen generator?
Bottled Nitrogen Costs
Generator Investment
Rule of Thumb: If you use nitrogen more than 40 hours per week, on-site generation typically pays for itself within 2-3 years and saves 50-70% on gas costs long-term.
Gas Cost Optimization Tips
1. Choose the Right Gas for Each Job
Don't use expensive nitrogen when oxygen will work. For structural mild steel parts that will be painted, the oxidized edge gets covered anyway. Save nitrogen for stainless, aluminum, and parts requiring clean edges.
2. Optimize Gas Pressure
Excessive pressure wastes gas without improving cut quality. Start at recommended pressure and reduce incrementally until you see edge quality degradation, then add 1-2 bar back. This can reduce consumption by 20-30%.
3. Fix Leaks Promptly
A small leak in your gas system can waste $500-1000/year. Check all connections regularly with leak detection spray. Common leak points: quick disconnects, regulators, and nozzle seals.
4. Consider Bulk Gas Delivery
If you use 5+ bottles per week, switch to bulk liquid nitrogen delivery. Cost per m³ drops by 30-50% compared to high-pressure cylinders. Requires on-site bulk tank (often provided by supplier).
5. Use Air for Non-Critical Parts
For thin mild steel prototype parts, test pieces, or internal brackets, compressed air can provide acceptable quality at minimal cost. Invest in an oil-free compressor with adequate CFM.