What Are the Characteristics of PCD Cutter Grinding?

With the rapid development of modern science and technology, the variety and performance of cutting tools made of superhard materials such as polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) are constantly improving.

Currently, PCD and PCBN cutting tools are widely used in industries such as automobile, aerospace, precision machinery, home appliances, wood, electronics, and electrical engineering. They are used to make tools such as turning tools, boring tools, milling cutters, drills, reamers, countersinks, broaches, saws, engraving tools, and razors.

PCD is made by sintering specially treated diamonds and a small amount of binder at high temperature and ultra-high pressure. The randomly oriented diamond grains give PCD uniform and extremely high hardness and wear resistance. However, the high hardness and wear resistance of PCD also bring great difficulties to its processing.

Many researchers have conducted extensive research and experiments on the processing difficulties brought by the high hardness and wear resistance of PCD materials, including electrical discharge machining, ultrasonic machining, electrochemical machining, laser machining, etc., and have achieved certain results. However, the analysis shows that these processing technologies are mostly suitable for rough processing of PCD materials.

The main grinding characteristics of PCD cutting tools are:

1. The grinding force of PCD cutting tools is very large

Diamond is the hardest mineral known, and the wear volume when frictionally paired with various metallic and non-metallic materials is only 1/50 to 1/800 of that of cemented carbide. The hardness (HV) of PCD is 80-120 KN/mm2, second only to single crystal diamond, far higher than cemented carbide.

2. The grinding ratio of PCD cutting tools is very small

Due to the high hardness and wear resistance of PCD, the grinding time is long and the processing efficiency is low in order to ensure the cutting edge quality and removal amount of the cutting tools. In addition, when the hardness, content and particle size of PCD are different, the grinding time also varies greatly.

3. The particle size of PCD cutting tools has a great influence

PCD material used for cutting tools is mainly divided into three categories according to particle size: coarse (20-50μm), medium (around 10μm), and fine (-5μm). Their grinding force and grinding ratio differ several times or even tens of times.

Coarse PCD has the highest grinding ratio and the most difficult grinding, and the tooth shape of the cutting edge after grinding is the most severe and the quality is the worst, but it has the strongest wear resistance. Fine PCD has the relatively lowest grinding ratio, and the grinding and the quality of the cutting edge after grinding are the best.

Although PCD cutting tools are developing so rapidly, the difficulty of tool sharpening caused by their high hardness has always troubled most users, and regrinding of blades is mainly done by the original tool manufacturers. This not only leads to high tool prices and long delivery times but also occupies the flow of funds for enterprises and institutions. Therefore, it is necessary to understand the grinding characteristics of PCD cutting tools mentioned above.