As we all know, the use of a laser cutting machine to cut thick metal plates often requires perforation on the plate firstly ,except in a few cases where the knife can be started from the edge of the plate,. In the early days, a punch was used to punch a hole on a laser punching compound machine, and then a laser was used to start cutting from the small hole. With the continuous improvement of laser power and the maturity of the process, direct laser perforation has become the mainstream.

Laser perforation can be divided into blast perforation and pulse perforation.

blast perforation

The material is irradiated by the continuous laser to form a pit in the center, and then the molten material is quickly removed by the oxygen stream coaxial with the laser beam to form a hole. Generally, the size of the hole is related to the plate thickness. The average diameter of the blasting perforation is half of the plate thickness. Therefore, for thicker plates, the blasting perforation has a larger aperture and is not round. It is not suitable for use on parts with higher requirements (such as oil screen pipes). ), which can only be used on scrap. In addition, since the oxygen pressure used for perforation is the same as that used for cutting, the splash is larger.

pulse perforation

In order to obtain better cutting quality, fiber laser cutting generally uses pulse perforation. Pulse perforation uses high peak power pulse laser to melt or vaporize a small amount of material. Air or nitrogen is often used as auxiliary gas to reduce the expansion of the hole due to exothermic oxidation. The gas pressure is lower than the oxygen pressure during cutting. Each pulse laser only produces small particle jets, which are gradually deepened, so that the diameter of the perforation is smaller, the sprayed slag is less, and the perforation quality is better than blasting perforation. After the perforation is completed, immediately change the auxiliary gas to oxygen for cutting, which can make the cutting start more stable.

Guidance of perforation method:

1. The peak power is as high as possible to improve the efficiency of perforation;

2. Ensure that the laser spot does not hit the nozzle, and the perforation focus is appropriately reduced;

3. The oxygen perforation air pressure is equivalent to the cutting air pressure;

4. Add stop light blowing between multi-level perforation, which is not easy to blast.