A Brief Discussion on the Past and Present of PDC Diamonds Tools

Diamond has been used as an ultra-hard tool material in cutting processing for hundreds of years. In the history of tool development, from the late 19th century to the mid-20th century, high-speed steel was the main representative of tool materials. In 1927, Germany first developed carbide tool materials, which were then widely used. In the 1950s, Sweden and the United States respectively synthesized artificial diamonds, marking the entry into an era represented by ultra-hard materials in cutting tools. In the 1970s, the high-pressure synthesis technology was used to synthesize PDC diamonds, solving the problems of the scarcity and high cost of natural diamonds, and expanding the application range of diamond tools to fields such as aviation, aerospace, automotive, electronics, and stone.

Diamond tools have the characteristics of high hardness, high compressive strength, good thermal conductivity, and wear resistance, which can achieve high processing precision and efficiency in high-speed cutting. These characteristics of diamond tools are determined by the crystal state of diamonds. In a diamond crystal, the four valence electrons of a carbon atom form bonds in a tetrahedral structure, with each carbon atom forming covalent bonds with four adjacent atoms, thus forming a diamond structure. This structure has strong binding force and directionality, giving diamond extremely high hardness. Although the structure of PDC diamonds are sintered body of fine diamond grains with different orientations and contains a binder, its hardness and wear resistance are still lower than those of single-crystal diamond. However, because the PCD sintered body is isotropic, it is not easy to crack along a single cleavage plane.

Main Indicators of PDC Diamonds

First, the hardness of PDC diamonds can reach 8000HV, which is 8-12 times that of carbide. Secondly, the thermal conductivity of PDC diamonds is 700W/mK, which is 1.5-9 times that of carbide, and even higher than that of PCBN and copper. Therefore, PCD tools can quickly transfer heat. Additionally, the friction coefficient of PCD is generally only 0.1-0.3 (the friction coefficient of carbide is 0.4-1), so PDC diamonds tools can significantly reduce cutting forces. Moreover, the thermal expansion coefficient of PCD is only 0.9×10^-6 to 1.18×10^-6, which is only 1/5 of that of carbide, so PDC diamonds tools have small thermal deformation and high processing precision. Furthermore, PCD tools have very low affinity with non-ferrous metals and non-metallic materials, making it difficult for chips to adhere to the cutting edge and form built-up edges during processing.

Main Applications of PDC Diamonds Tools

The range of applications for PCD tools has expanded from traditional metal cutting to processing materials such as stone, wood, metal matrix composites, glass, and engineering ceramics. Analysis of the applications of PCD tools in recent years shows that PCD tools are mainly used in the following two areas:

Processing of difficult-to-cut non-ferrous metal materials

When using ordinary tools to process difficult-to-cut non-ferrous metal materials, tools often wear easily and processing efficiency is low, whereas PCD tools can exhibit excellent processing performance.

Processing of difficult-to-cut non-metal materials

PCD tools are very suitable for processing difficult-to-cut non-metallic materials such as stone, hard carbon, carbon fiber reinforced plastic (CFRP), and artificial board materials.

PDC diamonds tools are an ideal cutting tool material and represent the direction of tool material development. Because carbide materials are non-renewable and increasingly scarce, PDC diamonds tool materials will achieve substitution in more fields.