What is a laser cutting nozzle?

The nozzle, commonly referred to as a copper nozzle, is a critical component in laser cutting. The nozzle is positioned at the bottom of the cutting head. The laser beam and auxiliary gas interact with the cutting material via the nozzle. The primary function is to collect auxiliary gas and generate high pressure, which is then released to the surface of the cutting material and the cutting seam, effectively removing the melted and vaporized parent material produced during the cutting process, resulting in a clean cutting seam. Simultaneously, it prevents the upward rebound of slag, smoke, and other pollutants, thereby safeguarding the internal lens.

How to select a laser cutting nozzle?

Laser cutting is presently acknowledged as a highly efficient, high-quality, and precise method of metal processing. The nozzle is one of the elements that influence laser cutting. Selecting an appropriate nozzle for cutting different materials might facilitate the processing. How to accurately select the appropriate nozzle? Let us examine today.

To get an improved cutting section, it is essential to regulate the concentricity of the laser beam and the nozzle’s center. They are a significant factor influencing cutting quality. Consequently, the nozzle must be coaxial with the laser beam to achieve an improved cutting section.

When the nozzle’s center is not aligned with the laser beam’s center, the cutting quality would be adversely affected.

• The cutting gas is expelled from the nozzle’s center, which coincides with the center of the plate to be cut. If the laser is misaligned within the nozzle, the focal point will diverge from the intended location, resulting in a noticeable discrepancy between the actual cutting effect and the anticipated outcome.
• If the laser is misaligned within the nozzle, the beam will contact the inner wall during standard operation, potentially resulting in nozzle damage and adversely impacting the cutting efficiency.

To ascertain the concentricity and coaxiality of the laser beam and the nozzle, the subsequent testing processes are necessary.

• Step 1. Affix transparent tape over the nozzle opening, ensuring complete coverage of the circular perimeter.
• Step 2. Set the equipment power to around 100W and utilize the point shooting mode to irradiate the transparent tape with the laser.
• Step 3. Detach the transparent tape and examine the spatial relationship between the circular edge and the laser perforation.

If the hole is centrally punctured in the circle, the laser beam is concentric with the nozzle, necessitating no adjustments; conversely, if the small hole is not coaxial with the circle’s center or is obscured (the laser beam contacts the nozzle’s inner wall), it is imperative to adjust the screw on the laser cutting head and reiterate steps 1-3 until the laser punching point aligns with the nozzle’s center.

Varieties of D28 nozzles available for selection

Standard nozzles are categorized into single-layer and double-layer types. Single-layer nozzles exhibit a comparatively low gas flow rate and are frequently employed for cutting stainless steel, aluminum alloy, copper, and several other metals. Nitrogen is frequently utilized as a supplementary gas. Double-layer nozzles have a rapid gas flow rate and are appropriate for high-velocity cutting. They are frequently employed to sever carbon steel. Oxygen is typically employed as a supplementary gas, resulting in a blackened cutting surface owing to oxidation.

High-speed single-layer nozzles encompass the SP-S, SP-F, and ST-S configurations. The primary distinctions are as follows.

• SP-S single-layer nozzles are primarily utilized for high-power, bright surface cutting of carbon steel exceeding 20mm in thickness, and may also be employed for rapid cutting with oxygen negative focus.
• ST-S single-layer nozzles are primarily utilized for high-power, bright surface cutting of carbon steel exceeding 20mm in thickness, providing stable follow-up and enhanced results.

Selection of nozzle size

The dimensions of the nozzle aperture dictate the gas flow rate impacting the cutting material, hence influencing the removal of the melt. A greater gas flow rate and increased velocity at the incision enhance the efficacy of spray and melt removal.

In principle, a thicker plate necessitates a larger nozzle. Nevertheless, an increased nozzle aperture heightens the likelihood of molten sparks splattering upward during cutting, hence reducing the lens’s lifespan.

Deformation of the nozzle or the presence of melt stains would adversely impact the cutting efficacy. Consequently, the nozzle must be positioned meticulously to prevent damage or distortion, and it should be promptly cleaned when melt residues are present.