Laser cutting has always been one of the most widely used techniques for green laser pointer processing. Pulsed lasers are suitable for metallic materials, continuous lasers are suitable for non-metallic materials, and the latter is an important application area for laser cutting technology. Combined with computer-controlled automatic equipment, the laser beam has unlimited contour cutting capability and easy cutting path modification. Laser cutting without mechanical deformation, no tool wear, easy to achieve automated production.
Laser cutting is widely used in sheet metal processing, metal processing, advertising production, kitchen utensils, automobiles, lamps, saw blades, elevators, metal crafts, textile machinery, grain machinery, glasses production, aerospace, medical equipment, instrumentation and other industries. In particular, it has replaced traditional processing methods in the sheet metal processing industry and is favored by industry users.
First, the laser cutting process
Laser cutting uses a high power density laser beam to illuminate the material being cut so that the material is quickly heated to the vaporization temperature and evaporates to form a hole. As the beam moves toward the material, the hole is continuously formed into a narrow width (eg, about 0.1 mm). Sew, complete the cutting of the material.
Green laser pointer cutting can be divided into laser vaporization cutting, laser melting cutting, laser oxygen cutting and laser dicing and control fracture.
1, laser vaporization cutting
The workpiece is heated by a high energy density laser beam, the temperature rises rapidly, the boiling point of the material is reached in a very short time, and the material begins to vaporize to form a vapor. These vapors are ejected at a high speed, and a slit is formed in the material while the vapor is ejected. The heat of vaporization of the material is generally large, so a large power and power density is required for laser vaporization cutting.
Laser vaporization cutting is mostly used for the cutting of very thin metal materials and non-metallic materials (such as paper, cloth, wood, plastic, rubber, foam, etc.). Ultrashort pulse lasers allow this technology to be applied to other materials. The free electrons in the metal absorb the laser and heat up sharply. The laser pulse does not react with the molten particles and plasma, the material directly sublimes, and there is no time to transfer the energy to the surrounding material in the form of heat. The picosecond pulse ablate the material without significant thermal effects, without melting and burring.
2, laser melting and cutting
When the laser is melted and cut, the metal material is melted by laser heating, and then a non-oxidizing gas (Ar, He, N, etc.) is blown through a nozzle coaxial with the beam, and the liquid metal is discharged by a strong pressure of the gas to form a slit. Laser melt cutting does not require complete vaporization of the metal, and the required energy is only 1/10 of the vaporization cut.
Laser melt cutting is mainly used for the cutting of some non-oxidizable materials or active metals, such as stainless steel, titanium, aluminum and their alloys, and also for cutting other fusible materials, such as ceramics.
3, laser oxygen cutting (flame cutting)
The principle of laser oxygen cutting is similar to oxyacetylene cutting. It uses a laser as a preheating heat source and uses an active gas such as oxygen as a cutting gas. On the one hand, the injected gas acts on the cutting metal to cause an oxidation reaction to release a large amount of heat of oxidation; on the other hand, the molten oxide and the melt are blown out from the reaction zone to form a slit in the metal. Since the oxidation reaction during the cutting process generates a large amount of heat, the energy required for laser oxygen cutting is only 1/2 of the melt cutting, and the cutting speed is much larger than the laser vaporization cutting and the melting cutting. Laser oxygen cutting is mainly used for easily oxidized metal materials such as carbon steel, titanium steel and heat-treated steel.
4, laser dicing and control fracture
Laser dicing is to scan the surface of the brittle material with a high energy density laser, so that the material is evaporated to a small groove by heat, and then a certain pressure is applied, and the brittle material is cracked along the small groove. The green laser pointer for laser scribing is generally a Q-switched laser and a CO2 laser.
Controlling the fracture is a steep temperature distribution created by laser engraving, creating local thermal stresses in the brittle material that cause the material to break along the small grooves.