What gases are needed for metal laser cutting machines?

When I first started working with laser cutting machines, I didn’t realize how much the choice of assist gas could affect performance. But over time, I saw how the wrong gas could ruin a job, while the right one could save money and improve quality.

Laser cutting metal requires the right gas to achieve clean edges, maintain material integrity, and avoid oxidation. The choice depends on the type of metal, machine type, and final application.

Some people think lasers alone do all the work. But the assist gas plays a bigger role than most realize. It impacts speed, cut quality, post-processing, and even the machine’s health. Let me explain how we do it at Kirin Laser, and what I’ve learned over the years.

Which gas is used in laser cutting?

In the beginning, many of our customers ask this: do I really need special gases to cut metal? The answer is yes, and the choice depends on what you’re cutting and the result you want.

Different gases serve different purposes. Oxygen speeds up cuts for carbon steel. Nitrogen protects the edges of stainless steel. Air works for budget-friendly jobs, and argon helps with sensitive materials like titanium.

Different materials, different gases

Choosing the right gas is like choosing the right tool for the job. Here’s how we approach it at Kirin Laser:

Oxygen – for carbon steel

Oxygen creates a reaction with carbon steel that speeds up the cutting process. It forms an oxide layer on the edge, which isn’t a problem if the part won’t be welded or painted later. It’s great for speed and thicker sections.

Nitrogen – for stainless steel¹

I always recommend nitrogen when cutting stainless. It doesn’t react with the metal, which means no oxidation and cleaner, shinier edges. This is essential if the part will be painted or welded afterward. It does cost more, especially at higher pressures, but the quality is worth it.

Compressed air – for aluminum and budget jobs²

Compressed air is a mix of mostly nitrogen and oxygen. It’s cheaper and still effective for thinner sheets. It won’t give the cleanest cuts, but it works when budget is a concern and edge quality isn’t critical.

Argon – for titanium and sensitive alloys³

Argon is inert, like nitrogen, but more stable. One of our clients had a problem with edge contamination on titanium parts. We switched them to argon, and the cuts were instantly cleaner. For high-value materials, this is the gas I trust.

Gas Type	Best For	Pros	Cons
Oxygen	Carbon steel	Fast cuts, deeper penetration	Oxidized edges
Nitrogen	Stainless, aluminum	Clean edges, no oxidation	Higher cost
Compressed Air	Aluminum, mild steel	Low cost, easy to use	Less precision
Argon	Titanium, alloys	No reaction, clean results	Very expensive

Can you cut metal with CO2 laser?

Some people ask me if a CO2 laser can handle metal cutting like a fiber laser. Technically yes, but practically it’s not always the best option.

CO2 lasers can cut metals, but they lack the efficiency and cost-effectiveness of fiber lasers, especially for reflective materials like aluminum or copper. Fiber lasers are better for most metal applications.

Why fiber is better for metals

Beam absorption

CO2 lasers struggle with reflective materials⁴ like copper and aluminum. The laser beam bounces off, reducing efficiency and risking machine damage. Fiber lasers, on the other hand, absorb better into these materials, making the process faster and safer.

Maintenance

CO2 lasers require more maintenance⁵. Their mirrors and lenses need frequent cleaning and replacement. Fiber lasers have fewer moving parts, which means less downtime and lower costs.

Speed and power

Fiber lasers deliver more energy to the material surface. They cut faster, especially on thin metals. In our production line at Kirin Laser, we switched to fiber years ago. It was a game-changer in terms of both speed and edge quality.

Applications

If you're cutting acrylic or wood, a CO2 laser is fine. But for stainless steel, aluminum, and carbon steel, I always recommend a fiber laser. The running cost is lower, and the performance is unmatched.

Are laser cutting fumes toxic?

Whenever I show someone a laser cutter in action, the first thing they notice is the smoke. They often ask if it’s dangerous. The short answer is yes—it can be, if you don’t manage it.

Laser cutting fumes can be toxic, especially when cutting plastics, coated metals, or composites. Using proper ventilation and filtration systems is essential for safety.

Safety always comes first

What’s in the fumes?

When metal is cut, especially coated or painted metal, it releases fumes containing metal particles, oxides, and possibly harmful chemicals. Stainless steel, for example, can release hexavalent chromium⁶—a known carcinogen.

Health risks

Exposure to these fumes over time can lead to respiratory issues, skin irritation, or more serious conditions. That's why I always tell clients: don’t cut corners on fume extraction⁷. It's not just about meeting regulations; it's about keeping your people safe.

Solutions we recommend

At Kirin Laser, we integrate fume extraction units into our machines or offer them as add-ons. We recommend multi-stage filters with HEPA and activated carbon⁸. For shops doing high-volume cutting, I also suggest placing the machine in a negative pressure room to prevent fumes from leaking.

Material Cut	Potential Fumes	Risk Level	Recommendation
Stainless Steel	Chromium, nickel oxides	High	Use HEPA + carbon filters
Painted Metals	VOCs, heavy metal dust	Medium-High	Pre-strip or isolate cutting
Plastics/Composites	Toxic gases, particulates	Very High	Avoid or use industrial scrubbers
Carbon Steel	Iron oxides	Medium	Use fume extractor

Is oxygen or nitrogen better for laser cutting?

This is one of the most common questions we get from distributors and end-users alike. The answer depends entirely on the metal and what you want your final product to look like.

Oxygen is better for faster cutting and thicker carbon steel. Nitrogen is better for high-quality, oxidation-free edges on stainless steel and aluminum.

Which one to choose and when

Oxygen – when speed matters

When cutting carbon steel thicker than 6mm, oxygen boosts the cutting speed⁹ through a reactive exothermic process. The reaction adds heat, allowing the laser to move faster. But it leaves an oxidized edge, which can affect welding or coating.

Nitrogen – when edge quality matters

If the part needs to be painted, coated, or welded, nitrogen is the better choice. It keeps the metal surface clean by blowing away molten metal without reacting with it. That’s why I always choose nitrogen for stainless steel.

Cost considerations

Oxygen is cheaper to run, especially at lower pressures. Nitrogen needs higher purity and pressure, which increases cost. But when quality is the goal, nitrogen pays for itself in fewer rejected parts and less post-processing.

My recommendation

For clients processing both materials, I advise setting up dual gas lines¹⁰ with easy switching. That way, you can choose oxygen for rough parts and nitrogen for finished parts without changing your setup completely.

Metal Type	Gas Used	Pros	Cons
Carbon Steel	Oxygen	Fast, efficient	Oxidized edges
Stainless Steel	Nitrogen	Clean, weld-ready edges	Higher cost, slower cutting
Aluminum	Nitrogen/Air	No oxidation, clean cuts	Air has less precision

Conclusion

Choosing the right gas for fiber laser cutting ¹¹ is not a minor detail—it’s a core part of the process. From oxygen’s speed to nitrogen’s clean finish, each gas plays a key role. In my work at Kirin Laser, I’ve seen how the right setup improves efficiency, reduces waste, and keeps clients satisfied. For anyone using or selling laser cutters, understanding your gas choices is essential to delivering quality and value.