Polycrystalline diamond (PCD) composite sheets are widely used in the tool industry due to their excellent hardness and wear resistance. The cutting process characteristics of this material directly affect its performance in practical applications. Therefore, it is particularly important to study the process parameters of laser cutting PCD composite sheets. This paper will explore the influence of different laser cutting parameters on the cutting quality and processing efficiency of PCD composite sheets, and provide a theoretical basis for achieving its efficient and high-quality cutting.

1. Basic characteristics of PCD composite sheets

Polycrystalline diamond composite sheets are composed of a layer of 0.3mm to 0.7mm diamond micropowder combined on a cemented carbide substrate through an ultra-high pressure and high temperature sintering process. This material has both the extremely high hardness and wear resistance of diamond, and the good toughness, strength and weldability of cemented carbide. Therefore, in the field of metal cutting and material processing, PCD composite sheets are often used in the processing of non-ferrous metals, ceramics, and composite materials. In industries such as automobile manufacturing and wood processing, PCD composite sheets have gradually become high-performance materials to replace traditional cemented carbides.

With the advancement of science and technology, the development trend of PCD products includes large diameter, small particles and high diamond content. These technological advances have made PCD materials more and more widely used in the market, and the market demand has gradually increased.

2. Cutting methods of PCD composite sheets

At present, there are two main cutting methods for PCD composite sheets: electric spark wire cutting and laser cutting. Although electric spark wire cutting is a mature technology, it may cause excessive removal of the cobalt-rich layer between polycrystalline diamond and cemented carbide during the cutting process, which often increases the difficulty of subsequent processing. In addition, due to the poor conductivity of diamond particles themselves, wire breakage is very likely to occur when using electric spark wire cutting, which greatly reduces the cutting efficiency.

In contrast, laser cutting has become a more ideal method for PCD composite sheet processing with its high efficiency, good cutting quality and easy control. Studies have shown that compared with electric spark wire cutting, laser cutting is several orders of magnitude more efficient and has obvious advantages in cutting quality and surface finish.

3. Influence of laser cutting process parameters

The process of laser cutting PCD composite sheets involves multiple process parameters, including laser power, cutting speed, pulse frequency and defocusing amount. The changes in these parameters not only affect the cutting efficiency, but also directly determine the cutting quality.

3.1 Laser power

Laser power is one of the key factors affecting cutting efficiency. Studies have found that higher laser power can increase the melting and evaporation rate of materials, thereby increasing cutting speed. However, too high power may also cause excessive thermal impact of materials, increase thermal damage, and affect the quality of cutting edges. Therefore, in practical applications, it is necessary to find a suitable power range.

3.2 Cutting speed

Cutting speed is also an important parameter that is directly related to processing efficiency. Although higher cutting speed can improve production efficiency, it may lead to an increase in cutting seam width and a decrease in surface roughness. Therefore, the cutting speed needs to be reasonably selected according to specific processing requirements to ensure that the desired cutting effect is achieved.

3.3 Pulse frequency

Pulse frequency refers to the frequency of laser emission, which affects the energy concentration of the beam and the cutting effect. Higher pulse frequency can usually improve the fineness of cutting, but it may also reduce the overall cutting speed. Therefore, when optimizing the pulse frequency, it is necessary to comprehensively consider the cutting accuracy and speed.

3.4 Defocus

Defocus refers to the distance between the laser focus and the cutting surface. Appropriate defocus can ensure the optimal focusing state of the laser beam, thereby improving the cutting quality. If the defocus is too large, the energy of the laser beam will be dispersed and the cutting ability will be reduced; while if the defocus is too small, it may cause problems such as material burning and overheating. Therefore, adjusting the defocus is an important part of optimizing the laser cutting process.

4. Laser cutting process test

In order to explore the influence of the above parameters on the cutting quality of PCD composite sheets, this paper uses a fiber laser to conduct a cutting test on a 1.6mm thick PCD composite sheet. The cutting surface and cross section are observed and analyzed by a digital microscope and an optical profiler to obtain quantitative data on the cutting quality.

4.1 Experimental design

In the experiment, the laser power of 150W, the cutting speed of 100mm/min, the pulse frequency of 60Hz, and the zero defocus were selected as cutting parameters, and the influence of these parameters on the cutting quality was systematically analyzed. After multiple groups of experiments, the best combination of laser cutting parameters was obtained.

4.2 Analysis of experimental results

The experimental results show that under the selected parameters, excellent laser cutting quality of PCD composite sheets is obtained. The slit width is 70μm, and the cutting surface is smooth and burr-free, which fully demonstrates that the selected process parameters can effectively control the cutting quality of PCD materials.

5. Discussion on the mechanism of laser energy action

In the process of analyzing laser cutting of PCD composite sheets, it is also necessary to explore the mechanism of laser energy action on materials. When laser energy passes through the surface of the material, it causes local high temperature, causing rapid melting and evaporation. Due to the high thermal conductivity of PCD, the transmission of laser energy is mainly concentrated in the cutting area, thereby improving the cutting efficiency.

The study found that short-pulse laser processing can more effectively improve the accuracy and efficiency of cutting. This is because short-pulse laser can greatly increase the absorption rate of laser energy by the material, while reducing the influence of heat conduction, so that the laser energy can be quickly concentrated at the cutting point, reducing thermal damage to the material.

6. Conclusion

In summary, this paper systematically studies the influence of laser cutting process parameters on cutting quality through the cutting test of PCD composite sheets with fiber laser. The experimental results show that the size of the energy density on the surface of the material is the key factor determining the quality of laser cutting. The optimal cutting parameters were determined by comprehensive analysis of laser power, cutting speed, pulse frequency, and defocus. This study provides a theoretical basis for optimizing the laser cutting process of PCD composite sheets, which is of great significance for improving material processing efficiency and cutting quality. In the future, further in-depth research on the effects of different lasers on PCD material cutting and the exploration of more efficient laser cutting technology will further promote the application and development of superhard materials.