introduction
The unique combination of diamond properties makes diamond a good material for precision and high productivity industrial applications. Since the introduction of high temperature and high pressure (HTHP) in the 1950s to produce single crystal synthetic diamonds, to the metal sintered polycrystalline diamond (PCD) developed in the 1970s, synthetic diamond materials have become the only substitute for natural single crystal diamond. Recently, with the advent of pure polycrystalline diamond materials developed by chemical vapor deposition (CVD) processes, it has broad prospects for improving tool performance at levels that were once thought impossible.
From wear-resistant coatings to pure, independent materials for high-tech lenses and electronic components, the industrial application of CVD diamonds is impressive. The main interest of the mechanical industry in CVD diamonds is the practical application of CVD diamond materials in high-performance cutting tools and dressing tools.
Unlike HTHP diamond and metal sintered PCD, CVD diamonds do not need to simulate the natural high pressures deep in the earth. In contrast, CVD diamond is excited with a mixture of hydrogen and hydrocarbon to an "activated" state of illumination that is not normally found in nature. It is this chemical principle of activation that allows pure CVD polycrystalline diamond to be deposited in the range of 800-1000 °C.
2 CVD diamond
A recognized application of CVD technology on the market is the "thin film" CVD diamond coating of tungsten carbide cutting tools. Whether it is a chip breaker blade or a fully plated screw end mill, diamond coating tools have been commercialized.
However, there is now a "thick film" CVD diamond process that can be used to make a pure, non-binder diamond monolithic form. Typical thicknesses for this form range from 150 to 1000 μm. This material is first vapor deposited as a separate sheet which is then laser cut into various shapes suitable for cutting tools.
3 Excellent performance of CVD diamond
An advantage of CVD diamond as a cutting tool material is its excellent combination of properties due to its unmatched hardness. Unlike metal sintered PCD, the unique properties of natural diamond are retained in CVD diamonds, even at high cutting temperatures. The hardness and modulus of elasticity of the single crystal diamond result in good wear resistance and dimensional stability of the CVD diamond.
In the silicon carbide "sand" test, the relative volume loss of the independent CVD diamond is four times lower than that of the PCD and 120 times lower than that of the tungsten cemented carbide. Unlike metal bonded PCD compacts, thick film CVD diamond materials are comparable to single crystal diamonds in hardness and wear resistance at high cutting temperatures, even exceeding the hardness and wear resistance of single crystal diamonds at high cutting temperatures. .
Like natural diamond, CVD diamond has a small coefficient of friction, resulting in less cutting force and functional consumption during cutting, as well as less frictional heat and superior anti-chipring properties.
In dry cutting or high speed machining, the reduction in cutting temperature caused by the high lubricity of CVD diamond is a major advantage over PCD and other materials. The thermal conductivity of CVD diamond applied to mechanically thick film CVD diamond materials is five times higher than that of tungsten carbide and 50% higher than that of PCD. The excellent thermal conductivity of CVD diamonds can be used as a safe way to dissipate heat from the cutting zone. The non-binder structured CVD diamond allows the tool to withstand aggressive machining temperatures up to 800 ° C, while the cobalt sintered PCD is thermally damaged when the machining temperature approaches 700 ° C. Although PCD can be used to remove cobalt to prevent the degradation of PCD quality, CVD diamond also has excellent wear resistance. The chemical properties of non-binder structured CVD diamonds are more stable than metal sintered PCD and tungsten carbide materials. When a corrosive polymer such as a phenolic resin of a synthetic material is processed by a CVD diamond coating tool, it has a long life, and the CVD diamond can also resist corrosion of the cutting fluid of the tool. The chemical instability caused by pure diamond and metal alloys containing iron, nickel or cobalt has historically limited the use of diamond in the cutting of ferrous and superalloys. However, diamond-containing materials such as PCD, single crystal diamond, and CVD diamond are still preferentially used in the machining of high-productivity ferrous materials.
4 CVD diamond tool manufacturing characteristics
Due to its polycrystalline structure, CVD diamond can produce fracture toughness (fracture resistance) over actual natural diamond. This feature has proven to be very beneficial in offensive machining such as interrupted cutting and wheel dressing. In general, the mechanical robustness of CVD diamonds is similar to the robustness of advanced ceramics.
Careful design and fabrication of fracture toughness, strength and other key properties of CVD diamond individual sheets can improve high performance tools for CNC rotating wheel dressing, high speed or near dry machining of aluminum and metal based composites.
The CVD diamond tool is manufactured in a similar manner to the PCD tool. The diamond blade is brazed to the notched corner of the tungsten carbide or high speed steel body, and the tool is refined with a diamond wheel. The sturdy brazing technology of thick-film diamond blades was developed in the 1990s. This technology solves the problem of bonding and tool body selection for metal-cutting films, diamond-coated carbide inserts. The bonding and tool body selection of diamond-coated carbide inserts for cutting has been widely considered to have a negative impact on cutting. Most independent thick film CVD diamond materials for cutting tools are approximately 0.5 mm thick. The relatively smooth, fine-grained (about 1 μm) nucleus surface is generally polished for use as a rake face for cutting tools; the side of the coarse particle surface (>50 μm) is vacuum brazed to the tungsten carbide body or High speed steel knife body.
Although the rigorous control of the CVD process is key, it is the tool manufacturing that ultimately determines the quality of the blade and the robustness of the tool. Most experienced manufacturers often use grinding wheels for the PCD industry, and they extend the grinding time to accommodate the increased hardness of CVD diamond materials.
J&M Diamond Tool Company grinds CVD diamond with PCD-finished grinding wheels. Compared to PCD tools, it takes 10% to 20% more time to grind a CVD diamond tool blade. However, extending the edge grinding time allows the tool manufacturer to achieve a surface roughness that is superior to that of the PCD tool. Since CVD diamond is more wear resistant than PCD, simply increasing the feed of the grinding wheel creates an excessive grinding force that damages the CVD diamond tool cutting edge.
Thick film CVD diamond can be used to produce a brazed, mirror surface roughness (Ra < 0.05 μm) cutting insert. This unique property of thick film inserts allows the workpiece to produce an excellent surface finish compared to thin film CVD diamond coatings. Thick film CVD diamonds also offer the opportunity to replace single crystal diamond tools in tool selection.
The robustness and wear resistance of the independent CVD diamond material make it an excellent choice for a wide range of machining applications such as high silicon aluminum milling. Tool life for CVD diamond machining of aluminum alloys is often 1.55 times longer than commercial PCD tool life. The actual improvement is determined by the design and manufacturing techniques of aluminum alloys and cutting tools. CVD diamond tools are often used to turn pistons for interrupted cutting required for general machining of aluminum wheel finishing and other high silicon aluminum materials and metal based composites. Although high silicon aluminum is always the subject of CVD diamond concentration research, diamond blade tools are becoming more and more popular in the machining of low silicon aluminum materials. High-productivity machining or precise finishing requires the use of diamond tools. An automotive manufacturing company finishes an aluminum part. The CVD diamond insert tool is not only 30% more durable than the PCD, but it can continuously process the required surface roughness throughout the life of the tool. Tungsten carbide is one of various precision machined materials for single crystal diamond, PCD and PCBN and recent CVD diamond. In one test, CVD diamond was used to boring tungsten carbide (25% Co) cylinders with a cylinder bore of 20 mm and a length of 40 mm. When the cylinder is boring, the coolant is sprayed at a cutting speed of 0.5 m/s, the feed rate is 0105 mm per revolution, and the cutting depth is 0.12 mm. As a result, the thick film CVD diamond tool can process 8 parts before failure, the PCD tool can process 5 parts, and the PCBN can only process one part.
5 CVD diamond dressing tool
Trimming tools generally remove blunt ceramic or abrasive particles from the surface of the grinding wheel, thereby striving to reduce the grinding temperature and improve the surface roughness of the workpiece, and improve the ability of the grinding wheel to machine small tolerance workpieces. The dressing tool is also used to refine the grinding wheel. In the past, most finishing and finishing operations were carried into a rotating grinding wheel using a fixed dressing tool, often made of single crystal diamond or PCD.
Today, many high-productivity grinding operations use rotating CNC dressers or sharp dressing rollers. When one side of the grinding wheel is machining the workpiece, the other side is continuously trimmed at the same time. The CNC Rotary Dresser accommodates more than 100 identical diamonds that are mounted on the outer diameter of the dresser to create a unique shape on the grinding wheel.
When laser cutting, the independent CVD diamond provides many unique advantages to the user and producer of the trimming tool. The structure of CVD diamond can be designed to have high fracture toughness and strength to optimize the life and dimensional stability of the trimming tool.
Since CVD diamond is cut into uniform pieces, it minimizes or eliminates the problems associated with single crystal diamonds, such as the inherent shape constraints and variability of natural diamonds. Finally, CVD diamond materials can be fabricated with high aspect ratios (eg, 8 mm x 1 mm x 1 mm). CVD diamonds are cost effective to mount on trimming tools, extending life and improving dressing efficiency.
in conclusion
The natural quality of vapor deposited diamond and the advanced manufacturing technology of independent CVD diamond tools provide an excellent solution for many difficult materials. With the success of CVD diamonds in finishing tools, CVD diamonds have been rapidly promoted and applied in the field of industrial material processing.
The slotted flange is a kind of flange. The sealing surface of ring groove surface is often used with butt welding connection type. Slotted flange is often used in high temperature, high pressure environment.
Rectangular Slotted Flange,Galvanized Slotted Flange,10K Slotted Flange,10K Slotted Type Flange
Jinan Xintai Forging Co., Ltd , https://www.xtdzflange.com