How should the "nozzle" of the cutting head be selected?

"The nozzle is selected correctly, doubling the efficiency.".

Although it is an inconspicuous small component, its function is not small. It not only prevents impurities such as molten stains from rebounding upward, but also controls the gas diffusion area and size. Therefore, nozzle quality is one of the important factors that determine the quality of cutting. Today, we will talk about how to select and match a "nozzle".

1.Do nozzles of different quality differ greatly?

"The difference is significant because the material and accuracy of the nozzle play a decisive role in conductivity, thermal conductivity, difficulty in debugging, and protection of the laser head. A good nozzle can protect the optical lens inside the cutting head, and release auxiliary gas to the surface of the cutting material and the cutting seam, guiding the gas to assist in cutting and remove molten slag, leaving a clean cut.", Therefore, the quality of the nozzle directly affects the life of the cutting head and the quality of the cutting workpiece.

Generally speaking, the price of nozzles provided by the original manufacturer of cutting heads is high, which also makes nozzles sold by third parties popular. However, not every third party manufacturer has the production capacity of such consumables.

In recent years, as the price war for fiber optic lasers has been raging, the price of laser accessories has also become increasingly low. blindly pursuing low prices while ignoring quality can only outweigh the gains and losses. 

2.What are the consequences of improper selection?

If the nozzle is improperly designed and maintained, and the processing accuracy is insufficient, the gas flow rate will decrease, and the airflow direction will become unstable, which will affect the melting of materials during the cutting process and produce molten stains. Cutting thicker plates may even cause inability to cut.

-Excessive nozzle selection-

Rough upper stripe and lower drag line (left)

Upper layer with rough stripes and teeth (right)

-Nozzle selection too small-

Insufficient cutting (left)

Cutting delamination (right)

3.What types of nozzles are available?

There are currently two main nozzle designs: "low-speed nozzle" (gas flow rate is less than the sound speed) and "high-speed nozzle" (gas flow rate is close to the sound speed). Factors affecting nozzle performance include cutting head cavity pressure, nozzle diameter, nozzle internal shape, and nozzle outlet shape.

High Speed Double Layer Nozzle and Storm Single Layer Nozzle

The working principle of high-speed nozzles is the same as that of rocket and jet engines, and they accelerate the gas entering the nozzle. Therefore, high-speed nozzles can produce better results for cutting viscous materials.

If ordinary low-speed nozzles are used, the surface air pressure of the workpiece will fluctuate greatly with the change of cutting height, resulting in unsatisfactory cutting results.

4.How to choose a nozzle?

You can choose from the following aspects:

Processing requirements: The single layer nozzle used in laser equipment is mainly used for nitrogen cutting stainless steel and aluminum plates; Double layer nozzles are mainly used for oxygen cutting of carbon steel.

Material: There are two commonly used materials for nozzles - red copper and brass. Red copper has better electrical conductivity and thermal conductivity than brass.

Size: The aperture size of the nozzle determines the flow rate of gas and the shape of the gas field. Generally, when cutting thin plates below 3mm, it is recommended to select a nozzle with a diameter of 1mm, while when cutting thin plates above 3mm, it is recommended to select a nozzle with a diameter of 1.5mm, and when cutting thin plates above 10mm, it is recommended to select a nozzle with a diameter of 2mm or more.

5.How to install and debug the nozzle?

Nozzle Installation Procedure

1. Unscrew the nozzle;

Replace the nozzle with a new one and retighten it with appropriate force;

After replacing the nozzle, the capacitance calibration must be performed again.

Taking the 12kW cutting head of the Wave Stinger as an example, the focal point is matched with a nozzle (calibration is required for 0 joules):

Double layer 1.2E: cut 3mm to 12mm carbon steel plate, between 5-11 focal points

Double 1.4E: Focus 9-14

Double layer 1.6E: Focus 11-16

Double layer 1.8E: focus 13-18

SP Single Layer 1.2: Focus 8-13

SP Single Layer 1.4: Focus 10-15

SP Single Layer 1.6: Focus 12-17

SP Single Layer 1.8: Focus 14-19

Machining accuracy: A good laser head nozzle should have a concentricity of 0.03 mm, while nozzles with sizes below 1.0 mm should have a concentricity of 0.02 mm. A high-precision concentric nozzle can not only reduce the preliminary debugging during the processing process, but also effectively prevent high-energy laser from hitting the inner wall of the laser head, thereby avoiding damage to the laser head.