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CVD/PCD Diamond Tool Brazing
Single crystal cutting tools is mainly in the field of ultra-precision machining cutting tool, the cutting tool is general quality is greater than 0.1 g, the path is not less than 2 mm long, which can realize the mirror machining, can work out high precision and low surface roughness of workpiece, cutting out the effect is very light, is recognized, ideal of ultra-precision machining tool. Single crystal knife has natural and man-made two kinds, the natural single crystal diamond quantity is small, the price is expensive, mainly used in high precision optical field.
Performance advantages of single crystal tool:
(1) Single crystal diamond cutting tool has very high hardness (10000HV), so as to obtain good wear resistance;
(2) The cutting edge of single crystal diamond tool can be sharpened, so it is not suitable to stick the tool and produce chip tumor during cutting, and ultra-thin cutting and ultra-precision machining can be carried out;
(3) Low friction coefficient, small deformation during machining, can reduce the cutting force;
(4) The cutting edge is observed without defects under 800 times Nomarski (Nikon) microscope, and the surface roughness can reach Rz0.1 ~ 0.05μm when machining non-ferrous metals, and the shape accuracy of the workpiece is controlled below 50nm;
(5) The use of selected single crystal diamond tool particles, good consistency, the service life is 100 times of carbide tool, even hundreds of times.
Single crystal tool category：
According to the equipment used in different working conditions (CNC machine tools, CNC machining centers, etc.), the different cutting technology, single crystal tool can be welded in different cutter bodies according to the need to make different cutting tools, commonly used single crystal tool types are: Natural diamond blade (single crystal cutter), single crystal diamond turning tool, single crystal milling cutter, single crystal chamfering cutter, natural diamond highlight cutter, single crystal ball milling cutter, etc.
ND/MCD/CVD/PCD tool difference
(1) Different materials: ND is a natural diamond. About 98% of natural diamond belongs to type Ia nitrogen [N] (~2500ppm). Most of the formation of natural diamond is produced in rocks at least 2.5 billion years old, and about 140~200 kilometers underground. The intense pressure at this depth (1.5 million pounds per square basal leaf) and extremely high temperatures (about 2,800℃) cause rare carbon atoms to clasp tightly together, forming crystalline structures.
MCD, is made of high temperature and high pressure method of artificial crystal, artificial crystal diamond belongs to one of Ib type synthetic diamond single crystal, nitrogen [N] are scattered or solid solution state exists in the crystal, artificial crystal, as the name suggests is made of synthetic diamond in an anaerobic and high temperature (above 1000℃) high pressure (500 million mpa) synthesized in the environment, Due to its high hardness, high wear resistance and high heat conductivity comparable to diamond. High temperature and high pressure method synthesis of single crystal tool, generally yellow.
CVD, a single crystal made by chemical vapor deposition, belongs to one of IIa diamond monocrystalline synthetic diamonds, nitrogen [N]< 1 ppm, [B] < 0.05 ppm, CVD synthesis of single crystal diamond is in the chamber of hydrogen and carbon mixture, chemical vapor deposition (CVD) to synthesize, CVD single crystal is generally colorless and transparent crystal. This is a high technology synthesized by the high quality single crystal diamond, can be totally colorless transparent, almost no impurities, have higher resistance to abrasion, and better heat transfer coefficient, are able to make machining surface of objects with higher quality, at the same time, if in the process of growth in selective mixed gas is piped in, with a variety of colored diamond can be prepared.
PCD polycrystalline diamond, is the use of natural or synthetic diamond powder and binder (containing cobalt, nickel and other metal) according to certain proportion, at high temperatures (1000 ~ 2000℃) and high pressure (5 ~ 100000 atmospheres) under the sintering and become fixed diameter and thickness of PCD compact, after cutting, welding, grinding and other processes, Make PCD tool. Normally, the thickness of PCD composite is about 0.3 ~ 1.0mm. It can be made into PCD blade, PCD turning tool, PCD milling cutter, PCD reamer, PCD drill and other structure forms.
CVD diamond thick film cutters is using plasma CVD method in Mo the depositing of diamond film substrates, independence of diamond thick film (0.3 1.3 mm), after the welding process, to CVD diamond thick film welding the carbide or other materials on the base of forming CVD diamond thick film cutting tools or blade, concrete molding process as shown in figure:
(2) Different appearance: natural single crystal tool is generally transparent, artificial single crystal is generally yellow or colored (CVD method), PCD tool is generally black.
(3) Performance difference: PCD tools are best suited for processing aluminum and other ductile non-ferrous alloys (such as copper, brass and bronze), as well as composite materials with high abrasive properties (such as graphite, carbon-carbon materials, carbonized phenolic, fiberglass and porous sealing materials).
Single crystal diamond is almost exclusively used for high precision finishing, and its extremely thin cutting ability ensures extremely high dimensional accuracy. PCD and CVD diamonds can be used in many of the same processing fields, but PCD is more suitable for rough machining and machining where the fracture toughness of the tool is required. CVD diamond is better at finishing, semi-finishing and continuous turning because of its excellent wear resistance and high hardness, which can produce more precise workpiece.
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