Analysis of Common Processing Methods for Laser Cutting of Metals（two）

3, oxidative melting cutting

Laser cutting processing melt cutting generally uses an inert gas. If it is replaced by oxygen or other reactive gas, the material is ignited under the irradiation of a laser beam, and a strong chemical reaction with oxygen produces another heat source called oxidative melting cutting. The specific description is as follows:

(1) The surface of the material is quickly heated to the ignition temperature under the irradiation of the laser beam, and then a fierce combustion reaction with oxygen is performed to release a large amount of heat. Under the action of this heat, a small hole filled with steam is formed inside the material, and the periphery of the small hole is surrounded by a molten metal wall.

(2) The combustion material is transferred into slag to control the burning speed of oxygen and metal, and the speed at which oxygen diffuses through the slag to reach the ignition front also has a great influence on the burning speed. The higher the oxygen flow rate, the faster the combustion of the chemical reaction and the removal of the slag. Of course, the higher the oxygen flow rate, the better, because too fast a flow rate will result in rapid cooling of the reaction product at the exit of the slit, ie, the metal oxide, which is also detrimental to the quality of the cut.

(3) Obviously, there are two heat sources in the oxidative melting and cutting process, namely the laser irradiation energy and the thermal energy generated by the chemical reaction between oxygen and metal. It is estimated that when cutting steel, the heat released by the oxidation reaction accounts for about 60% of the total energy required for cutting. It is apparent that the use of oxygen as an auxiliary gas results in a higher cutting speed than an inert gas.

(4) In the oxidative melting cutting process with two heat sources, if the burning speed of oxygen is higher than the moving speed of the laser beam, the slits appear wide and rough. If the laser beam moves faster than oxygen, the resulting slit is narrow and smooth.

4, control fracture cutting

For brittle materials that are easily damaged by heat, high-speed, controlled cutting by laser beam heating is called controlled fracture cutting. The main content of this cutting process is that the laser beam heats a small area of brittle material, causing a large thermal gradient and severe mechanical deformation in the area, causing the material to form cracks. As long as a balanced heating gradient is maintained, the laser beam can direct the crack to occur in any desired direction.

It should be noted that this controlled fracture cutting is not suitable for cutting acute and angular slits. Cutting a large closed shape is also not easy to succeed. Control the fracture cutting speed is fast, do not need too high power, otherwise it will cause the surface of the workpiece to melt and destroy the edge of the slit. The main control parameters for laser cutting are laser power and spot size.

The above is a summary of the common treatment methods for metal laser cutting. It can be seen that the specific steps of metal laser cutting are still relatively rigorous. It is precisely because of these rigorous steps that metal laser cutting products will be more beautiful. Firm Metal - CNC Flame Cutting