Working principle of laser marking machine

Laser marking is the physical and chemical reaction of melting, vaporization, heating and discoloration of the workpiece under the action of high-energy laser beam, so as to leave a permanent mark on the surface of the workpiece. According to the different laser energy used, the action mechanism of laser marking can be divided into the following types;

1. heating to change color marking

When most materials (especially some non-metallic materials, such as plastic, paper, rubber, etc.) are heated by laser, the material itself will undergo chemical changes, which will change the surface color of the marked workpiece or brighten its surface gloss. Therefore, this mechanism can be used for marking.

The change of material color during laser heating only occurs on the surface of the material, which is caused by the change of metal metallographic structure or the change of non-metallic chemical composition. It is generally difficult to predict the color change of these materials, especially plastic materials, under the action of laser.

Sometimes the same type of plastic produced by different manufacturers will change into different colors. The laser marking machine in mask mode mostly uses this method for marking. The power density required by this marking method is low, the temperature of the marking part is below the melting point of the material, and the deformation of the material caused by marking is very small. It is suitable for laser marking on non-metallic materials.

2. melting marking

After the metal is heated to the melting point, due to the oxidation of the metal or the incorporation of other impurities, the color of the surface of the metal will also change after it solidifies again. For example, the color of marks produced by melting some steels will darken. When there is an oil film on the surface, a mark with great contrast will be produced on the surface.

This method can also be used for laser marking. Since the surface profile of metal does not change before and after marking, this form of marking method has great advantages in some applications. For example, the surfaces of bone splints, artificial spinal connectors, cardiac pacemakers, etc., which are widely used in medicine, are required to be as smooth as possible, so it is best to use this method for marking. The melting marking method is also suitable for some plastic materials. When they melt, they will form grooves on the surface or change the structure of other surfaces.

3. vaporization marking

Most materials will evaporate and vaporize when their surface temperature is higher than the melting point. For example, steel, aluminum, titanium, copper and other metal materials, when nd; When YAG laser beam moves on its surface, the surface is easy to vaporize and form a groove, resulting in obvious marks.