Briefly describe the main characteristics of PCD grinding

The grinding process of PCD is mainly the result of a mixture of mechanical and thermochemical aspects. The mechanical action is the micro-cracking, abrasion, shedding or cleavage of the diamond formed by the continuous impact of the diamond grinding wheel abrasive grains on the PCD material; the thermochemical action is the high temperature formed by the diamond grinding wheel grinding PCD to oxidize or graphitize the diamond. The result of the mixed action of the two causes the PCD material to be removed. The main characteristics of the grinding process are:

(1) Great grinding force

Diamond is the hardest substance among known minerals. The wear amount of friction with various metal and non-metal materials is only 1/50～1/800 of cemented carbide; the hardness (HV) of PCD is 80～ 120KN/mm2, second only to single crystal diamond, much higher than cemented carbide. When using a diamond wheel to grind PCD, the initial cutting strength is very high, about 10 times that of cemented carbide (0.4MPa); the specific grinding can reach 1.2104～1.4105J/mm3; therefore the grinding force is much higher than that of grinding Cemented carbide.

(2) Grinding ratio is very small (Guide: Two ways of rotating axis of vertical five-axis machining center)

Due to the high hardness and wear resistance of PCD (relative wear resistance is 16 to 199 times that of cemented carbide), the grinding ratio when grinding PCD is only 0.005 to 0.033, which is about 1 of that of cemented carbide. /1000～1/100000; The grinding efficiency is only 0.4～4.8mm3/min. Therefore, in order to ensure the quality and removal of the cutting tool's edge, the grinding time is very long and the processing efficiency is very low. In addition, when the hardness, content, and particle size of PCD are different, the grinding time is also very different.

(3) Granularity has a great influence

PCD materials used for cutting tools are mainly divided into three categories according to the particle size: coarse particle size (20-50μm), medium particle size (about 10μm) and fine particle size (~5μm). The grinding force and grinding ratio are several times different. To dozens of times. Coarse-grain PCD has the highest grinding ratio and the most difficult to grind. After grinding, the cutting edge has the worst serration and worst quality, but has the strongest wear resistance; fine-grain PCD has the relatively lowest grinding ratio and is easier to grind. The cutting edge quality is the best after grinding.

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