How to Choose and Use Laser Cutting Nozzle

During the laser cutting process, the nozzle of the laser head collects the capacitive signal and transmits it to the signal processor through the ceramic ring, so as to keep track of the distance between the laser head and the workpiece during the cutting process of the laser cutting machine. In this way, the gas is guided to pass through the workpiece to be cut smoothly, and a high pressure is formed near the outlet of the nozzle to speed up the cutting speed, take away the slag, and protect the internal lens of the laser head.

Type of nozzle

Generally, laser cutting nozzles are divided into single and double layers. The single-layer nozzle is used for fusion cutting, that is, nitrogen is used as auxiliary gas, and it is usually used for cutting stainless steel, aluminum alloy, brass, etc. Double-layer nozzles are generally used for oxidation cutting, that is, using oxygen as an auxiliary gas, usually for cutting carbon steel.

Nozzle Size Selection

The diameter of the nozzle determines the shape of the gas flow entering the incision, the gas diffusion area, and the gas flow rate, thereby affecting the removal of the melt and the stability of the cutting. The air flow entering the incision is large, the speed is fast, and the position of the workpiece in the air flow is appropriate, the stronger the ability of the jet to remove the melt.

The user selects the nozzle size according to the laser power used and the thickness of the metal sheet to be cut. Theoretically, the thicker the plate, the larger the nozzle size, the larger the proportional valve setting pressure, and the larger the flow rate, the normal section effect can be cut.

The coaxiality between the nozzle exit hole and the laser beam is also one of the important factors that affect the cutting quality. Especially when the workpiece being cut is thicker, its influence is greater. Therefore, the concentricity between the nozzle center and the laser must be adjusted to obtain a better cutting section.

When the center of the nozzle is not in the same axis as the center of the laser beam, the impact on the cutting quality is as follows:

The cutting gas is ejected from the center of the nozzle and acts on the cutting plate. According to the positive and negative directions of the X axis and the Y axis, the laser spot can be divided into four areas. When the laser is not in the center of the nozzle, the effects of the four sections are prone to be inconsistent. For example, when cutting thick carbon steel plates with a small nozzle, some surfaces have a bright surface effect, and some surfaces have thick stripes, and even slag hangs or cuts continuously.

The bright surface effect of 10kW+ Laser cutting Machine for cutting carbon steel is currently using small nozzles combined with high-focus technology. When the laser is not in the center of the nozzle, it is easy to cause the nozzle to heat up, affect the follow-up, cannot process stably, and seriously burns the nozzle directly.

The choice of nozzle is also related to the power of the laser. When the laser power is less than or equal to 6000W, a nozzle with a double-layer S1.0~5.0 diameter is generally used to cut carbon steel. Use a common specification single-layer nozzle to cut stainless steel.

When the laser power is ≥6000W, for 10~25mm carbon steel bright surface cutting, the diameter of the selected cutting nozzle is generally double-layer high-speed E-type S1.2~1.8E or the single-layer fan-type diameter is generally D1.2~1.8. Use a common specification single-layer nozzle to cut stainless steel.

The above is the relevant introduction about the correct selection and use of laser cutting nozzles, contact Senfeng for professional after-sales guidance.

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