(1) Blast drilling: The material is subjected to continuous laser irradiation to form a pit in the center, and then the molten material is quickly removed by an oxygen flow coaxial with the laser beam to form a hole. The size of the general hole is related to the thickness of the plate, and the average diameter of the blasting perforation is half of the plate thickness. Therefore, for thicker plates, the blasting perforation hole diameter is larger and not round, and it is not suitable for use on parts with higher requirements (such as oil sieve tube), and can only be used on waste materials. In addition, due to the same oxygen pressure used for perforation as during cutting, there is a larger splash.
(2) Pulse drilling: High peak power pulsed laser is used to melt or vaporize a small amount of material, and air or nitrogen is commonly 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 that gradually penetrate deeper, so the perforation time for thick plates takes a few seconds.
Once the perforation is completed, immediately replace the auxiliary gas with oxygen for cutting. This way, the perforation diameter is smaller and the perforation quality is better than that of blasting perforation. The laser used for this should not only have a high output power; The time and spatial characteristics of the light beam are more important, so generally transverse flow CO2 lasers cannot meet the requirements of laser cutting. In addition, pulse perforation requires a reliable gas path control system to achieve switching of gas types and pressures, as well as control of perforation time.