Which nitrogen or oxygen is more suitable for cutting steel
Laser cutting is a thermal processing process in which a laser beam acts as a processing tool. The specific parameters used in this process, such as laser power and assist gas type, will severely affect the overall quality and processing time during operation. The most commonly used auxiliary gases are oxygen and nitrogen. Choose them according to the type of material to be cut, the thickness and the required edge quality.
Traditionally, oxygen is most commonly used when cutting steel. Thin steel does not need a lot of power consumption due to the combustion process. The combustion process involves the chemical reaction of oxygen and iron, which releases a lot of heat and light energy. Because oxygen is involved in the cutting process, this is the limiting factor for cutting speed. For example, the cutting speed of using oxygen as an auxiliary gas for thin steel will be the same for a 1500-6000 watt laser.
When cutting stainless steel or aluminum, nitrogen is usually used to achieve better cutting quality. Unlike oxygen, nitrogen acts as a protective gas when cutting materials, preventing the combustion process and allowing the laser to quickly vaporize the material. This means that power is the decisive factor in cutting speed, and greater power equals greater speed.
In various applications, laser power has been steadily increasing. This development provides laser users with reasonable choices to meet their processing needs.
In order to make the right decision between oxygen and nitrogen, the following criteria must be considered:
(1) Processing speed
(2) Secondary processing , Including the required edge quality
(3) Operating cost
Let us study these three factors in detail:
Processing speed. As mentioned earlier, the oxygen cutting speed is limited by the power that can be applied, while the nitrogen cutting speed is directly related to the power. In some cases, the use of nitrogen and higher laser power when cutting thin steel is three to four times faster than when using oxygen.
Secondary processing. Nitrogen can provide smooth and excellent edge quality, which is very suitable for powder coatings, and can also ensure a suitable welding surface. This cutting method usually does not require any secondary processing. However, the oxide surface produced by oxygen cutting will affect powder coating and welding, and sometimes the surface needs to be treated to be suitable for powder coating.
Operating costs. The main influencing factor of operating costs is the rate of auxiliary gas consumption, and there is a significant difference between oxygen and nitrogen. Treatment with oxygen can lower operating costs because the gas consumption rate can be 10 to 15 times lower than that of nitrogen. Generally speaking, as the thickness increases, the consumption of nitrogen as an auxiliary gas also increases.
Combining all the factors, the following conclusions can be made:
In thin steel processing, if the cost is higher and the production quality is better For high parts, nitrogen should be selected as the auxiliary gas. As the thickness of the material increases, it becomes difficult to cut with nitrogen. If the parts to be produced require secondary processing, users must weigh the costs of additional processes and processing to determine which is more cost-effective to use nitrogen or oxygen.