Many people buying laser marking machines or second-hand laser marking machines. They don’t know how to judge the quality of laser marking machines. Generally, the quality and performance of a laser marking machine are directly determined by the product effect of marking. In fact, this is unscientific, because laser marking will change the marking speed, marking effect and marking power according to the corresponding materials. For laser marking processing, the idea of Xiaobian is to evaluate its processing quality mainly through the following principles:
1. The marking surface is smooth without brittle fracture
When the fiber laser marking machine marks the thick plate at high speed, the molten metal will not appear in the notch at the bottom of the laser beam, but it will be sprayed by the laser beam. As a result, the curve formed on the marking edge closely follows the moving laser beam. In order to solve this problem, we can only reduce the speed at the end of the marking process, so as to greatly eliminate the generation of lines.
2. Size of marking gap
The marking width is narrow, which is mainly related to the diameter of the laser beam spot. Generally speaking, the notch width of the optical fiber laser marking machine does not affect the marking quality. The marking width has an important impact, forming part of a particularly accurate configuration file. This is because the cutting width determines the interior with the smallest contour. When the thickness of the plate increases, the marking width will increase. Therefore, in order to ensure the same high accuracy, no matter how large the marking width is, the workpiece should be constant in the processing area of the laser marking machine.
3. Heat effect of marking materials
As an application equipment of thermal marking processing, optical fiber laser marking machine is bound to have a thermal impact on metal materials in the process of use, which mainly includes three aspects:
a. Heat affected zone
b. Pitting and corrosion
c. Material deformation
The heat affected area refers to the area heated along the notch in laser marking. At the same time, the structure of the metal changes. For example, some metals harden. The heat affected area refers to the depth of the area where the internal structure changes; Depression and corrosion have adverse effects on the surface of the marking edge and affect the appearance. They appear in the marking errors that should be avoided in general; Finally, if marking causes the part to heat sharply, it will deform. This is particularly important in fine machining because the contours and connecting pieces are usually only a few tenths of a millimeter wide. Controlling laser power and using short laser pulses can reduce component heating and avoid deformation.
In addition to the above principles, the state and final forming of the molten layer in the process of laser marking directly affect the above processing quality evaluation indexes.
The surface roughness of laser marking mainly depends on the following three aspects:
1. Adjustable process parameters during marking, such as power, marking speed, auxiliary gas type and pressure, etc;
2. Inherent parameters of the marking system, such as spot mode, focal length, etc;
3. Physical parameters of processing materials, such as laser absorptivity, melting point, viscosity coefficient of molten metal oxide, surface tension of metal oxide, etc.
In addition, the thickness of machined parts also has a great impact on the surface quality of laser marking. Relatively speaking, the smaller the thickness of the metal workpiece, the higher the roughness grade of the marking surface. Therefore, buying and selling laser marking machines from professional laser manufacturers is the best choice.
