The right choice of laser cutting nozzle doubles the efficiency.
Although it may seem like a small and inconspicuous part, its role is not insignificant. It needs to resist the rebound of molten debris and control the area and size of gas diffusion.
Therefore, the quality of the nozzle for laser cutting head is one of the important factors that determine the quality of laser cutting. Today, we will discuss how to choose the right nozzle.
Is there a big difference between nozzles of different qualities?
Yes, there is a significant difference, as the material and precision of the nozzle play a decisive role in conductivity, thermal conductivity, difficulty of adjustment, 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 and slit of the cutting material, guiding the gas to assist in cutting and removing the slag, leaving a clean cut.
Therefore, the quality of the nozzle directly affects the lifespan of the cutting head and the quality of the workpiece being cut.
Generally speaking, the nozzles that come with the original cutting head are priced higher, which has made third-party nozzles very popular. However, not every third-party manufacturer has the production capacity for such consumables.
In the price war of fiber laser cutters in recent years, the prices of laser cutter accessories have also been driven down. Pursuing low prices blindly and ignoring quality will result in more harm than good.
What are the consequences of improper selection of nozzles?
If the nozzle design and maintenance are not appropriate, the processing accuracy may be insufficient, resulting in a reduction in the gas flow rate and unstable airflow direction, which can affect the melting of materials during the cutting process and produce molten debris. Thicker materials may even become impossible to cut.
Selecting a nozzle that is too large
Rough upper stripes with serrated edges (right)
Selecting a nozzle that is too small
What are the types of nozzles?
Currently, there are two main types of nozzle designs: “low-speed nozzle” (gas flow rate is lower than the speed of sound) and “high-speed nozzle” (gas flow rate is close to the speed of sound).
Factors that affect the performance of the nozzle include the gas pressure in the cutting head cavity, the diameter of the nozzle, the internal shape of the nozzle, and the shape of the nozzle outlet.
The working principle of a high-speed nozzle is similar to the exhaust principle of a rocket or jet engine, which has an accelerating effect on the gas entering the nozzle. Therefore, a high-speed nozzle can produce better cutting results for viscous materials.
If a regular low-speed nozzle is used, the surface pressure of the workpiece will fluctuate significantly as the cutting height changes, which can lead to unsatisfactory cutting results.
How to select a nozzle?
There are several factors to consider when selecting a nozzle:
Processing needs: Single-layer nozzles used in laser equipment are mainly used for cutting stainless steel and aluminum plates with nitrogen, while double-layer nozzles are mainly used for cutting carbon steel with oxygen.
Material: Nozzles are commonly made of two materials, purple copper and brass. Purple copper has better conductivity and thermal performance than brass.
Size: The aperture size of the nozzle determines the gas flow rate and the shape of the gas field. Generally, when cutting sheets below 3mm, it is recommended to use a nozzle with a diameter of 1mm, and for 3mm or more, a nozzle with a diameter of 1.5mm is recommended. For cutting over 10mm, a nozzle with a diameter of 2mm or above is recommended.
Processing accuracy: A good laser head nozzle should have a concentricity of 0.03mm, while nozzles with a size of 1.0mm or less should have a concentricity of 0.02mm or better. Nozzles with high-precision concentricity not only reduce the initial debugging during the processing, but also effectively avoid damage to the laser head caused by the high-energy laser hitting the inner wall of the head.
Introduction to common nozzles
There are several types of nozzles commonly used in industrial applications. Here are some of the most common ones:
Single-Layer Nozzle
Features: Conical inner wall with high gas flow rate for slag blowing.
Purpose: Melting cutting of materials such as stainless steel and aluminum plate.
Double-Layer Nozzle
Features: Double-layer composite nozzle with an added inner core on the basis of a single-layer nozzle.
Purpose: Double-layer 2.0 or larger for carbon steel sand cutting
High-speed Double-Layer Nozzle
Features: The nozzle has a pointed shape, and the three holes on the edge of the inner core are larger than those of a regular double-layer nozzle.
Purpose: It is mainly used for high-power, high-speed, and high-quality cutting of carbon steel up to 20mm thickness with a smooth and bright surface finish.
High-speed Single-Layer Nozzle
Features: The nozzle has a pointed shape, with a conical inner wall that features a stepped design.
Purpose: It is mainly used for high-power, high-speed cutting of carbon steel with a thickness above 20mm, resulting in a smooth and bright surface finish. It is also suitable for oxygen-focusing cutting applications.
High-speed Single-Layer Nozzle
Features: The nozzle has a pointed shape with a conical inner wall and a larger nozzle orifice area.
Purpose: It is mainly used for high-speed cutting of carbon steel with a thickness above 20mm, resulting in a smooth and stable cutting performance with better cutting quality.
Boost Nozzle
Features: Improved from a single-layer nozzle, the nozzle has a step layer at the nozzle orifice.
Purpose: It can be used for high-power cutting of stainless steel and carbon steel with nitrogen or compressed air at low pressure.
How to install and adjust a nozzle?
Nozzle Installation Steps:
- Unscrew the old nozzle.
- Install the new nozzle and tighten it with appropriate force.
- After replacing the nozzle, recalibrate the capacitance.
As an example, for a BLT 12kW laser cutting head with a focal point paired with a nozzle (0 focal point must be calibrated):
- Double-layer 1.2E nozzle: for cutting 3mm-12mm carbon steel plate, focal points between 5-11.
- Double-layer 1.4E nozzle: focal points between 9-14.
- Double-layer 1.6E nozzle: focal points between 11-16.
- Double-layer 1.8E nozzle: focal points between 13-18.
- SP single-layer 1.2 nozzle: focal points between 8-13.
- SP single-layer 1.4 nozzle: focal points between 10-15.
- SP single-layer 1.6 nozzle: focal points between 12-17.
- SP single-layer 1.8 nozzle: focal points between 14-19.
It is important to properly install and calibrate the nozzle to ensure optimal performance and cutting quality.
Recommendations for common nozzles
| Laser | Cutting thickness (bright surface cutting of carbon steel with oxygen) | Suggested nozzle |
|---|---|---|
| Low power laser (≤6000W) | 16-20mm | 1.4D-1.6D general conical nozzle |
| High power laser (≥6000W, using Raycus 12kW as an example) | 3-12mm | 1.2E dual-layer high-speed nozzle |
| 12-14mm | 1.2B-1.4E dual-layer high-speed nozzle | |
| 16-20mm | 1.4E-1.6E dual-layer high-speed nozzle | |
| 22-35mm | SP1.4-SP1.8 single-layer high-speed nozzle or 1.4E-1.8E dual-layer high-speed nozzle |
|
| 35-40mm | SP1.6-SP1.8 single-layer high-speed nozzle or 1.6E-1.8E dual-layer high-speed nozzle |
The quality of nozzles on the market varies greatly. It is recommended to carefully distinguish them according to the above content and purchase through regular channels.
