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In laser cutting, the choice of nitrogen (N₂) and oxygen (O₂) mainly depends on the type of material to be cut, cutting quality requirements, and cost effectiveness. The following is a comparative analysis of the two and suggestions for applicable scenarios:

The applicability of nitrogen (N₂)

Advantages:

1. No oxidation cutting

- Applicable materials: stainless steel, aluminum, titanium alloy, brass and other non-ferrous metals or high reflective materials.

- Effect: Nitrogen as an inert gas can prevent the oxidation reaction between the material and oxygen during the cutting process, and the edge of the incision is smooth and no oxide layer, reducing the need for subsequent grinding or painting.

2. High surface quality

- Clean cutting surface, suitable for precision machining with strict surface requirements (such as medical equipment, electronic product parts).

3. Avoid slag residue

- High purity nitrogen (more than 99.9%) can effectively blow molten metal under high pressure, reducing slag adhesion.

Cons:

1. High cost

- Large nitrogen consumption (high pressure, high flow), and high purity nitrogen is expensive, especially for thick plate cutting costs significantly increased.

2. The cutting speed is slow

- No exothermic reaction, completely dependent on laser energy to melt the material, cutting speed is lower than oxygen assisted cutting.

Second, the applicability of oxygen (O2)

Advantages:

1. Exothermic reaction accelerates cutting

- Applicable material: carbon steel (such as low carbon steel, medium carbon steel)

- Principle: Oxygen reacts with high temperature metal oxidation (Fe + O₂ → FeO + heat), releasing additional heat energy and significantly increasing cutting speed (30% to 50% faster than nitrogen).

2. Good economy

- Low oxygen cost, and due to reaction heat release can reduce laser power requirements, suitable for high-volume carbon steel processing.

3. Advantages of thick plate cutting

- For thick carbon steel plates (such as more than 20mm), oxygen assistance can effectively penetrate and maintain cutting efficiency.

Cons:

1. Oxidation problem

- The edge of the cut will form an oxide layer (black or yellow), requiring subsequent treatment (such as grinding, painting), affecting the surface quality.

2. Not applicable to non-ferrous metals

- Aluminum, stainless steel and other materials cut in oxygen tend to produce high melting point oxides (such as Al₂O₃), resulting in poor cutting quality or even failure.

Iii. Other precautions

1. Gas purity requirements

- Nitrogen: ≥99.9% (recommended for stainless steel cutting more than 99.99%).

- Oxygen: purity ≥99.5% to avoid impurities affecting reaction efficiency.

2. Gas pressure and flow

Nitrogen usually requires a higher pressure (e.g., 20 to 30Bar) to blow away the melt.

- Low oxygen pressure (e.g. 10 to 15Bar), but subject to material thickness adjustment.

3. Alternatives

- Air cutting: the lowest cost, but only suitable for thin carbon steel or the quality of the scene is not high, the incision oxidation is obvious.

- Mixed gas: Some scenarios use nitrogen-oxygen mixture (such as cutting galvanized sheet), balancing speed and oxidation problems.

In SUMMARY:

- Nitrogen: If the cutting material is non-ferrous metal such as stainless steel or aluminum, or the incision finish is required (such as appearance parts and precision parts).

Choose oxygen: if cutting carbon steel and pursuing efficiency and cost advantages, especially suitable for thick plate processing.

- Trade-off between economy and quality: nitrogen is preferred for high value-added products, oxygen is preferred for high-volume carbon steel processing.

Flexible gas selection according to specific needs can significantly improve laser cutting efficiency and control costs.

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