For CNC cutting tools to achieve the state of "being hard without being brittle, and tough without being soft", the key lies in the reasonable combination of material proportioning, structural design, and process treatment. Through the collaboration of these three aspects, a balanced adaptation of hardness and toughness can be achieved.
Ⅰ. Regulation of Material Proportion: Optimizing Performance from the Source
①. Cobalt is added to cemented carbide as a binding component, and the amount of cobalt added is usually between 3% and 10%. The higher the content, the better the toughness, but the hardness will decrease slightly, which can be flexibly adjusted according to the actual application scenarios.
②. Through the scientific proportioning of alloying elements such as chromium, molybdenum, and tungsten, combined with quenching and tempering treatments, high-speed steel maintains a hardness level of HRC 63-66 while further enhancing its impact resistance.
③. Adopt a composite material combination scheme, such as PCD or CBN blades paired with cemented carbide tool bodies. The cutter head is responsible for high-hardness cutting operations, while the tool body provides stable toughness support.
II. Optimization of Structural Shape: Reducing Stress Concentration Issues
①. blade edge is rounded or chamfered to avoid chipping caused by stress concentration at sharp edges, enhancing impact resistance while ensuring cutting sharpness.
②. Optimize the tool groove design, such as increasing the bending curvature of the chip flute, reducing the sudden change in the thickness of the groove wall, and decreasing the vibration and stress accumulation during the cutting process.
③. cutter body adopts a hollow structure or a stepped design. On the basis of ensuring rigidity, it absorbs impact energy through structural deformation to improve overall stability.
III. Upgrade of Process Treatment: Making Up for Performance Shortcomings
①. Cemented carbide adopts sintering technology with fine grains or even ultra-fine grains. The smaller the grain size, the more ideal the synergistic effect between hardness and toughness.
②. Perform surface coating processes, such as TiAlN and AlCrN coatings, which can not only increase the surface hardness to above HV3000 but also reduce friction loss during cutting, thereby indirectly protecting the toughness of the cutting edge.
③. Perform passivation treatment on the cutting edge, remove microcracks on the cutting edge through slight grinding, so that the hardness performance can play more stably and avoid brittle fracture.
