1. Introduction
Laser cutting technology plays an important role in modern manufacturing, especially in the processing of polycrystalline diamond (PCD). The structure of PCD CNC laser cutting machine mainly includes machine frame, CNC worktable, Z-axis focusing system, laser bracket and other components. These components work together to enable laser cutting technology to efficiently and accurately process diamond composite materials.
2. Laser processing mechanism
The mechanism of laser processing of polycrystalline diamond is: the laser emits a laser beam with extremely high energy density and irradiates it on the surface of polycrystalline diamond. Part of the light energy is absorbed by the surface and converted into heat energy, and the temperature of the local area of the irradiated spot rises rapidly to tens of thousands of degrees. The instantaneous high temperature causes the PDC to melt and vaporize locally, forming holes. At the same time, heat diffusion begins, and the material around the spot also melts.
As the laser energy continues to be absorbed, the steam in the pit expands, the pressure increases, and the molten material is ejected at high speed in the form of an explosion. The recoil pressure generated by the ejection forms a strong shock wave in one direction inside the workpiece. In this way, polycrystalline diamond erodes part of the material under the action of high-temperature melting vaporization and shock wave to form a slit, and finally cuts the PDC into the desired shape.
3. Laser cutting parameters
During the laser cutting process, the laser parameters that determine the cutting effect include pulse width, maximum pulse power and average pulse power. In addition, there are many factors that affect the cutting quality, such as:
• Different laser wavelengths and lens focal distances will produce different spot sizes.
• The intensity and spot diameter of the laser beam determine the energy density on the surface of the workpiece.
• The material, surface state and laser wavelength of the workpiece determine the change in reflectivity and the absorption rate of the input energy.
• The conductivity and thermal diffusivity of the workpiece affect the transfer of heat inside the workpiece.
Therefore, during the laser processing process, it is necessary to optimize the various process parameters of laser cutting through experiments.
4. Real-time monitoring and adjustment
When laser cutting PDC, the operator can observe the PDC laser cutting process in real time by observing the screen device, and adjust the working state of the equipment in real time according to the cutting situation. This real-time monitoring can effectively avoid the generation of waste sheets and ensure the quality of cutting.
5. Advantages of laser cutting
One of the advantages of laser cutting over wire EDM is that it is easy to integrate with the CNC system, easy to realize processing automation, and has better processing flexibility. Users only need to input the PCD shape, spot diameter, cutting parameters and auxiliary functions into the CNC system according to the specified graphic or data format, and the CNC laser cutting automatic programming software system can automatically write the processing program and complete a series of operations, making the processing process fully automated.
This automation not only improves the processing accuracy and production efficiency, but also ensures the stability of product quality, and can meet the requirements of large-scale industrial production in the future to a greater extent.
6. Limitations of wire EDM
Wire EDM is currently also widely used in PCD cutting. However, when using wire EDM to process PDC, the discharge intensity is difficult to control, which will cause damage to the surface of the PDC material. This not only affects the quality of the cutting surface, increases the tool grinding allowance, but also affects the life of the tool. In addition, the speed of wire EDM is much slower than that of laser cutting, and the effect is not ideal.
In contrast, laser cutting is a non-contact processing with excellent characteristics in PCD material processing. It can process high-purity PCD materials (such as polycrystalline diamond film), with very small processing deformation and thermal deformation, and laser processing is fast and efficient, making it a relatively effective processing method.
7. Conclusion
Laser cutting technology has shown its unique advantages in the processing of polycrystalline diamond, especially in micro-hole processing and non-conductive superhard material processing. Laser cutting has the advantages of small slit, high efficiency, small heat-affected zone, and no mechanical stress on the slit edge. It is considered to be an ideal method for cutting PDC. With the continuous advancement of technology, laser cutting will play a greater role in future industrial production.
