The selection of tool materials has a great influence on tool life, processing efficiency, processing quality and processing cost. When cutting tools are subjected to high pressure, high 

temperature, friction, impact and vibration, appropriate tool materials should be selected. The following basic properties:

(1) Hardness and wear resistance. The hardness of the tool material must be higher than the hardness of the workpiece material, usually required to be higher than 60HRC. The higher the 

hardness of the tool material, the better the wear resistance.

(2) Strength and toughness. The tool material should have high strength and toughness to withstand cutting force, impact and vibration, and prevent brittle fracture and broken edge of the 

tool

(3) Heat resistance. The tool material has good heat resistance, can withstand high cutting temperature, and has good oxidation resistance.

(4) Process performance and economy. The tool material should have good forging performance, heat treatment performance and welding performance. , and pursue high performance-price 

ratio.

Types, properties, characteristics and uses of tool materials

1. Types, properties and characteristics of diamond tool materials and their applications Diamond is an isomer of carbon and is one of the hardest materials in nature. Diamond tools have high 

hardness, high wear resistance and high thermal conductivity, and are widely used in the processing of non-ferrous metals and non-metallic materials, especially in the high-speed processing 

of aluminum and si-Al alloys. Diamond tools are the main cutting tools that are difficult to replace. High-efficiency, high-stability and long-life diamond tools are indispensable tools in modern

CNC processing.

Types of diamond tools:

(1) Natural diamond cutting tools: Natural diamond has been used as a cutting tool for hundreds of years. Natural single crystal diamond tools can be finely ground to grind extremely sharp 

blades with a blade radius of 0.002μm, which can achieve ultra-thin cutting and can process workpieces with high precision and low surface roughness. It is recognized and ideal and cannot 

replace ultra-precision machining tools.

(2) PCD diamond tools: Natural diamonds are expensive, and diamonds are mainly used for machining or polycrystalline diamond (PCD). Since the early 1970s, polycrystalline diamond 

(Polycrystauinediamond, later known as PCD blades) has been prepared using high temperature and high pressure synthesis technology. In many cases, natural diamond cutting tools have 

been replaced by artificial polycrystalline diamonds. PCD raw materials are abundant and the price is only one-tenth to one-tenth of natural diamonds. The tool cannot grind a very sharp edge

, and the surface quality of the machined workpiece is not as good as natural diamond. Therefore, PCD blades with chip breakers are not easy to manufacture industrially, so PCD can only be 

used for fine processing. CVD diamond tools: CVD diamond technology appeared in Japan since the late 1970s and early 1980s. CVD diamond refers to a method of synthesizing diamond 

films on heterogeneous substrates (such as cemented carbide, ceramics, etc.) by chemical vapor deposition (CVD). CVD diamond has the same structure and properties as natural diamond, 

and the performance of CVD diamond is very close to that of natural diamond. It has the advantages of natural single crystal diamond and polycrystalline diamond (PCD), and overcomes their 

disadvantages to a certain extent.

2. Performance characteristics of diamond tools:

(1) Extremely high hardness and wear resistance: Natural diamond is the hardest substance found in nature, and diamond has extremely high wear resistance. The service life of diamond tools 

is 10 to 100 times, or even hundreds of times, longer than that of cemented carbide tools.

(2) Has a very low friction coefficient: The friction coefficient between diamond and some non-ferrous metals is lower than that of other tools. The low friction coefficient means less 

deformation during processing, which can reduce cutting force.

The cutting edge is very sharp: The diamond cutting edge can be very sharp, and the natural single crystal diamond tool can reach 0.002 to 0.008 m, ultra-thin cutting and ultra-precision 

machining.

(3) It has a very high thermal conductivity: The thermal conductivity and thermal diffusion coefficient of diamond are very high, the cutting heat is easily dissipated, and the cutting 

temperature of the cutting tool is very low.

(4) Low thermal expansion coefficient: The thermal expansion coefficient of diamond is several times smaller than that of cemented carbide, and the tool size change caused by cutting heat is 

very small, which is especially important for precision and ultra-precision machining with high dimensional accuracy requirements.

Application of diamond tools Diamond tools are mainly used for high-speed finishing and boring of non-ferrous metals and non-metallic materials, and are suitable for processing various 

wear-resistant non-metallic materials, such as glass fiber reinforced plastic powder metallurgy blanks, ceramic materials and other wear-resistant non-ferrous metals, such as various si-Al 

alloys; finishing of various non-ferrous metals. The disadvantage of diamond tools is poor thermal stability. When the cutting temperature exceeds 700℃~800℃, it will completely lose its 

hardness. In addition, since diamond (carbon) at high temperature easily interacts with iron atoms and carbon atoms to form a graphite structure, it is not suitable for cutting ferrous metals. 

The cutting tool is very easy to damage.