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Diamond powder refers to diamond particles with particle size smaller than 36 / 54 μ m, including single crystal diamond dust and polycrystalline diamond dust. Due to the large production and wide application of single crystal diamond dust, diamond powder suppliers generally refer to diamond dust as single crystal diamond dust. Single crystal diamond dust is made of synthetic diamond single crystal abrasive particles by static pressure method, which are crushed and shaped, and produced with a special process of super hard materials. Diamond dust with high hardness and good wear resistance can be widely used in cutting, grinding, drilling, polishing, etc. It is an ideal raw material for grinding and polishing hard alloy, ceramics, gemstone, optical glass and other high hardness materials. Diamond dust products are tools and components made of diamond dust.

Polycrystalline diamond powder is made of graphite by a unique directional blasting method. The shock wave of directional blasting of high explosive speed accelerates the flying speed of metal flyer and impacts the graphite flake, resulting in the transformation of graphite into polycrystalline diamond. Its structure is very similar to that of the natural Carbonado diamond. Its particles are composed of tiny diamond grains which are combined by unsaturated bond and have good toughness. However, due to the limitation of synthesis conditions, there are few diamond powder suppliers and high product cost. At the same time, the particle size that can be provided in batches is not more than 10 microns, which limits its application field.

1. Introduction of PCD tool

As a superhard tool material, Diamond dies has been widely used in cutting. The high price of natural diamond has restricted the development of diamond tools. In the 1970s, people used high-pressure synthesis technology to synthesize Polycrystalline diamond (PCD), which solved the scarcity of natural diamond The problem of high price makes the application range of diamond tools extend to aviation, aerospace, automobile, electronics, stone and other fields.

Polycrystalline diamond (PCD) tools are mainly used to process non-ferrous metals such as non-ferrous metals, can sharpen the sharp edges, get a better processing surface, and are also the first choice for processing non-metallic new materials. And industrial ceramics and other high-hardness products.

2. Performance advantages of PCD tools

1) The hardness of PCD can reach 8000HV, which is 80 ~ 120 times that of cemented carbide, and the wear resistance of PCD is better.

2) The thermal conductivity of PCD is 700W / MK, which is 1.5-9 times that of cemented carbide, even higher than PCBN and copper. Therefore, the heat transfer of the PCD tool is rapid, and good heat transfer can extend the tool life to a large extent.

3) The friction coefficient of PCD is generally only 0.1 to 0.3, while the friction coefficient of cemented carbide is 0.4 to 1. Therefore, PCD tools can significantly reduce cutting forces, thereby extending tool life.

4) The thermal expansion coefficient of PCD is small, so the thermal deformation of PCD tools is small, and the processing accuracy is high. The greater the thermal deformation of the tool, the worse the surface quality of the processed workpiece. To process a workpiece with a good surface quality, the thermal deformation of the tool must be strictly controlled.

5) The affinity of PCD cutters with non-ferrous and non-metallic materials is small, and the cutting edge is not easy to form a built-up edge during the machining process. The affinity of the tool and the material to be processed is small, so the material to be processed is not easy to adhere to the surface of the tool during the processing process, and it is not easy to form a built-up edge.

6) The PCD tool has a large elastic modulus, high fracture strength (three times higher than alumina), the cutting edge blunt radius value can be ground very small, it is not easy to break, and it can maintain the sharpness of the cutting edge for a long time.

3. The structure of PCD cutter

Polycrystalline diamond (PCD) cutters are cutters made by welding PCD composite sheets to carbide or steel cutter bodies. Because the PCD composite sheet combines the high hardness, wear resistance, low friction coefficient and strength of single crystal diamond with the high bending strength of tungsten carbide cemented carbide, the tungsten carbide cemented carbide layer of the composite sheet provides the diamond layer The mechanical support increases its flexural strength, and at the same time the carbide layer is easy to weld, making it easy to make finished tools.

The structure of PCD tools are: PCD inserts, PCD milling cutters, PCD reamers, PCD drill bits, PCD grooving cutters, non-standard PCD cutters.

4. Processing material of PCD tool

1) Difficult to process non-ferrous metals and their alloy materials When processing non-ferrous metals such as copper, zinc, aluminum and their alloys, sintered hard alloys, titanium alloys, and pasteurized alloys, the materials tend to stick to the tool, and the processing is difficult. The metal is bonded to the tool and the tool has a long service life. For titanium alloys, copper alloys, tungsten carbide cemented carbides (Co <16% and Co> 16%), aluminum alloys (4-8% Si and 9-13% Si), high-silicon aluminum alloys (> 13% Si) , CDW010 grade PCD cutters are applicable. For alloy materials with higher wear resistance requirements, coarse-grained and mixed-grained PCD cutters CDW025 and CDW302 can be used. 2) Difficult to process non-metallic materials, such as glass fiber reinforced plastics, silicon-filled materials, hard carbon fiber / epoxy composite materials, ceramics, wood, serious tool wear, difficult to process, PCD tools have high hardness and good wear resistance, High processing efficiency, commonly used PCD materials are CDW010, CDW025 and CDW302.

5. The performance of PCD tool material grade

In addition to the structure of conventional PCD tools, PCD chipbreaker blades, PCD milling blades and non-standard PCD tools can be customized.

Application conditions and processing characteristics of PCD material grades

6. Selection of PCD tools

The main considerations for the selection of PCD tools: surface accuracy, shape accuracy, dimensional accuracy, tool deformation, shortened work cycle, shortened downtime, increased tool life, hard materials, tool costs, reduced investment, and others.

7. Cutting parameters of CBN tool

(1) Cutting speed-Vc
The PCD tool can be cut at a very high spindle speed, for example, when turning silicon aluminum alloy, the speed can reach 1000m / min, and high-speed milling 3000m / min;

(2) Feed amount-Fr
According to different processing conditions, the PCD tool should choose the appropriate feed amount. If the feed amount is too large, the surface roughness will be affected, and if it is too small, the cutting temperature will rise;

(3) Cutting depth-ap
PCD tools should choose the appropriate cutting depth according to different processing techniques. Excessive cutting depth will affect the tool life.

8. Common application areas of PCD tools

(1) 3C industry: As consumers demand more and more light, thin, short, small and fashionable, the new technology based on high-tech digitalization, intelligence and networking-"3C" products (Computer, Communication, ConsumerElectronics) endlessly, the number and variety of products is extremely rich. In the case of "3C" products, magnesium aluminum alloy has gradually replaced ABS, PC and other materials. With the development of 5G communication technology, new materials ceramics (zirconia) are more and more used in mobile phone back shells and other fields.

(2) Automotive industry: Aluminum alloy has become an ideal material for the transportation industry to reduce weight. There are many kinds of aluminum alloys in the market, and the Si content of automobile pistons, wheels, engine skirts, pin holes and cylinder blocks More than 10%, at the same time, it adopts the pipeline operation method, so it has high requirements on the hardness and service life of the tool, and the metal matrix composite material (MMC) and carbon fiber composite material have also been applied to the automobile field. Speed and processing quality.

(3) Aerospace industry: The most common composite material used in aerospace is CFRP (carbon fiber W strong plastic). Carbon fiber composite materials currently account for about 50% of the fuselage materials, and PCD tools are particularly effective for it. Typical CFRP parts are the spar of the aircraft, as well as bearings, pump parts and sleeves made of this part material. 

Polycrystalline Diamond powder is made from graphite using a unique directional blasting method. The shock wave of the directional blasting of high-explosive explosives accelerates the flying metal sheet and impacts the graphite sheet, resulting in the conversion of graphite into polycrystalline diamond. Its structure is very similar to that of natural diamond. It is made of unsaturated bonds and has good toughness.

Characteristics of polycrystalline diamond
The structure is very similar to the natural Carbonado. It is composed of spherical crystallites with a crystallite size of only 3-10 nm.

Excellent grinding performance: high removal rate and toughness, self-sharpening

Compared with single crystal diamond, it is less prone to surface scratches. It is more suitable for grinding workpieces whose surface is composed of different hardness materials.

Production process of polycrystalline diamond
The first production invention of polycrystalline diamond was invented by DuPont of the United States. The key to production is to use the detonation method to obtain fine powder raw materials.

Application fields of polycrystalline diamond
As a precision abrasive, it is used for ultra-precision grinding and polishing of sapphire, magnetic heads, hard disks, hard glass and crystals, ceramics and hard alloys, such as thinning of LED sapphire. As a coating additive, it is used for coating of metal molds, tools, parts, etc., which can greatly improve surface abrasion resistance, surface hardness, and extend service life. It is mainly used for grinding. It is also possible to make knives, which are less prone to chipping during cutting.

Our company is a professional polycrystalline diamond supplier. Welcome to contact us.

1. Overview
   
   Superhard tools play an important role in the automotive, aerospace, energy, military and mechanical fields. Super-hard tools refer to tools made of super-hard materials such as diamond and CBN and their composite materials. At present, PCD (Polycrystalline Diamond) tools and PcBN (polycrystalline cubic boron nitride) tools are mainly used. Polycrystalline diamond is a polycrystalline material obtained by sintering diamond fine powder with a metal binding agent such as cobalt under high temperature and high pressure. Although the hardness is slightly lower than that of single crystal diamond, its grains are arranged disorderly, isotropic, and have no cleavage plane. Polycrystalline diamond cutters have a low coefficient of friction, excellent thermal conductivity and low coefficient of expansion. Its hardness is 2 to 4 times that of cemented carbide, and the tool life is more than 10 times that of cemented carbide. Moreover, the price of raw materials used for polycrystalline diamond is dozens of times lower than that of natural diamond. Polycrystalline diamond composite chip cutters use cemented carbide as the base material, have weldability and good compatibility with polycrystalline diamond, and have good toughness and hardness. Therefore, polycrystalline diamond has both the hardness of diamond and the toughness and weldability of cemented carbide.
   
   Development history of polycrystalline diamond cutters- superabrasive

As a super-hard tool material, diamond has been used in processing for hundreds of years. During the development of the tool, the tool material for the knife was from about 1890 to 1950, and the typical material used was high-speed steel. Germany pioneered the development of cemented carbide materials in 1927, and subsequently, cemented carbide materials were widely used in the field of tool manufacturing. From 1950 to 1959, with Sweden and the United States successfully synthesizing synthetic diamonds, superhard materials—diamonds began to gradually replace cemented carbide materials as the main knife tool materials. From 1970 to 1979, with the successful birth of polycrystalline diamond prepared using high-pressure synthesis technology, synthetic polycrystalline diamond became an effective substitute for natural diamond. The material problems of diamond tools have been effectively solved, making the use of diamond tools from stone, electronics and automobiles to the aerospace industry.

3. Polycrystalline diamond cutters characteristics

Diamond tools have the advantages of high hardness, high compressive strength, good thermal conductivity and good wear resistance. These characteristics (advantages) are closely related to the crystal state of diamond. The reason why diamond is extremely hard is that in diamond crystals, four valence electrons of carbon atoms are bonded in a tetrahedral structure, and each carbon atom forms a covalent bond with four adjacent atoms. This structure has strong directivity and adhesion. Polycrystalline diamond is sintered with fine-grained diamond and binder with different orientations. Because of this, polycrystalline diamond has the characteristics of polyisotropy. Although its abrasion resistance and hardness are not as good as single crystal diamond, it is more difficult to crack along a single cleavage plane than single crystal diamond, and it also has hardness and abrasion resistance that are second only to single crystal diamond.

The surface Vickers hardness of polycrystalline diamond is greater than or equal to 1800 HV. The surface Vickers hardness of cemented carbides is far less than that of polycrystalline diamond. Polycrystalline diamond tools do not suffer from heat collection and workpiece burns due to slow heat extraction during the production process, because their thermal conductivity is higher than Cu, and is up to 700W / mK. The cutting force of polycrystalline diamond tools can be significantly reduced because the friction coefficient of polycrystalline diamond tools is generally only 0.1 to 0.3, which is only about one-third of the friction coefficient of cemented carbide. The coefficient of thermal expansion of polycrystalline diamond is only 0.0000009 to 0.00000118, which is about one fifth of that of cemented carbide. In addition, polycrystalline diamond cutters are not easy to produce sticky knives during production and use, and chips are not easily adhered to the tip to form chips, because the affinity between polycrystalline diamond and non-metallic and non-ferrous metal materials is extremely low.

Polycrystalline diamond tools are mainly used in the following two aspects:

(1) He is mainly used for the processing of non-ferrous metal materials. If ordinary tools are used, defects such as tool wear and low processing efficiency are easy to occur. Polycrystalline diamond tools can show excellent processing performance.
(2) For the processing of non-metallic materials, polycrystalline diamond cutters are suitable for processing non-metallic materials that are difficult to process, such as stone, hard carbon, CFRP and wood-based panels.