1. Provide support and enhance the strength: PCD layer is extremely hard but relatively brittle, the cemented carbide backing has high strength and impact toughness, which can provide solid support for the PCD layer, so that when the composite piece is subjected to external forces such as cutting force, impact force, etc., the PCD layer is not easy to rupture, flake, etc., which greatly improves the overall strength and reliability of the composite piece and ensures that the cutting tool stays intact during the cutting process, and can withstand large cutting loads. It can withstand large cutting loads.
2. Improvement of impact resistance: In the process of cutting, the tool may encounter various impact loads, such as the instantaneous impact force during intermittent cutting. The good toughness of the cemented carbide backing can effectively absorb and buffer these impact energies, reduce the impact on the PCD layer, prevent the PCD layer from cracking or breaking due to the impact, so that the PCD cutter can adapt to more impact cutting conditions, such as milling, intermittent turning and so on.
3. Realize good welding performance: the carbide backing has good welding compatibility with the cutter body material (such as steel, carbide, etc.), which makes it easy to firmly weld the PCD composite piece to the cutter body by brazing. Compared with directly welding the PCD layer to the cutter body, the cemented carbide backing can obtain higher welding strength and stability, to ensure that there will be no loosening, falling off and other problems between the composite piece and the cutter body in the cutting process, to ensure the normal use of the tool.
4. Improvement of thermal conductivity: Although PCD itself has better thermal conductivity, the carbide backing also has a certain thermal conductivity, which can assist the PCD layer to conduct the heat generated during the cutting process faster, reduce the temperature of the cutting area, and reduce the accumulation of heat in the PCD layer. This helps to improve the durability of the tool, prevent the PCD layer from deterioration of performance, graphitization and other problems due to overheating, and extend the service life of the tool.
5. Adjust the thermal expansion coefficient to match: The linear expansion coefficient of PCD is very small, while the thermal expansion coefficient of the tool body material is usually larger. The thermal expansion coefficient of cemented carbide backing is between PCD and cutter body material, which can play a transition and adjustment role between PCD layer and cutter body, reduce the thermal stress difference between PCD layer, backing and cutter body due to the temperature change in the cutting process, avoid delamination and cracking of composite piece caused by excessive thermal stress, and improve the stability of the combination of composite piece and cutter body.
6. Reduce manufacturing cost: PCD material cost is high, the use of carbide backing can reduce the use of PCD material under the premise of ensuring the performance of the tool, thus reducing the manufacturing cost of the tool. At the same time, the existence of cemented carbide backing also makes the manufacturing process of PCD composite piece relatively simplified, improving the production efficiency and further reducing the cost.
