Any kind of thermal cutting technique, except in a few cases where you can start at the edge of the plate, generally involves piercing a small hole in the top of the plate. In the early days of laser stamping and laminating machines a hole was punched first and then the laser was used to cut from the hole. With the continuous improvement of laser power and the gradual maturity of the technology, direct laser perforation has become mainstream. So what is laser cutting machine perforation?

　　(1) blast perforation: the material by continuous laser irradiation in its center to form a pit, and then by the laser beam coaxial oxygen flow will be molten material quickly remove the formation of holes. The general size of the hole with the thickness of the plate, the average diameter of the blast perforation plate thickness of half, so the thickness of the plate blast perforation hole diameter is larger and not round, is not suitable for the use of higher requirements of the part. In addition to the perforation due to oxygen pressure and cutting the same so the splash is also larger.

　　(2) Pulsed perforation: The peak power of the pulsed laser is used to melt or evaporate a small amount of material, and air or nitrogen is commonly used as an auxiliary gas due to the exothermic oxidation, lowering the hole dilation and the gas pressure is less than the oxygen pressure when cutting. Each laser pulse produces only a small jet of particles, which gradually penetrate, so it takes several seconds for the plate to perforate. Once perforation is complete, the auxiliary gas is replaced by oxygen for cutting. The quality of the shot holes is superior to the smaller diameter blast shot holes. So the requirement for the laser is not only a high output power; more important is the spatio-temporal characteristics of the beam.

　　In the case of pulsed perforation, in order to obtain a high-quality cut, attention needs to be paid to the transition technology from pulsed perforation when the workpiece is stationary to uniform continuous cutting. Theoretically, it is usually possible to change the cutting conditions in the accelerated section, such as the focal length, nozzle position, gas pressure, etc., but in practice, due to the short time, the above conditions are impossible to change. In industrial production, it is more realistic to change the average laser power, i.e. to change the pulse width. Change the pulse frequency; pulse width and frequency change at the same time.