There are three common cutting processes for laser cutting machines when cutting carbon steel:

Positive focus double-jet cutting
Use a double-layer nozzle with an embedded inner core. The commonly used nozzle caliber is 1.0-1.8mm. Suitable for medium and thin plates, the thickness varies according to the power of the laser cutting machine. Generally, 3000W or less is used for plates below 8mm, 6000W or less is used for plates below 14mm, 12,000W or less is used for plates below 20mm, and 20,000W or less is used for plates below 30mm. The advantage is that the cut section is beautiful, black and bright, and the taper is small. The disadvantage is that the cutting speed is slow and the nozzle is easy to overheat.

Positive focus single-jet cutting
Use a single-layer nozzle, there are two types, one is SP type and the other is ST type. The commonly used caliber is 1.4-2.0mm. Suitable for medium and thick plates, 6000W or more is used for plates above 16mm, 12,000W is used for 20-30mm, and 20,000W is used for 30-50mm. The advantage is fast cutting speed. The disadvantage is that the droplet height is low and the board surface is prone to shaking when there is a skin layer.

Negative focus single jet cutting
Use a single-layer nozzle with a diameter of 1.6-3.5mm. Suitable for medium and thick plates, 12,000W or more for 14mm or more, and 20,000W or more for 20mm or more. The advantage is the fastest cutting speed. The disadvantage is that there are scratches on the surface of the cut, and the cross section is not as full as the positive focus cut.

In summary, the positive focus double-jet cutting speed is the slowest and the cut quality is the best; the positive focus single-jet cutting speed is faster and is suitable for medium and thick plates; the negative focus single-jet cutting speed is the fastest and is suitable for medium and thick plates. According to the thickness and requirements of the plate, choosing the appropriate nozzle type can allow the fiber laser cutting machine to achieve better cutting results.