Dry cutting has higher requirements for the tool, such as the material of the tool, the structure of the tool and the coating of the tool. In conventional cutting, the cutting fluid in wet cutting plays an important role, but there are also many drawbacks. For example, maintaining a large cutting fluid system requires a lot of money, and requires regular addition of preservatives, replacement of cutting fluids, etc., which increases the cost, and the cost ratio has accounted for 15% to 17% of the total production cost, while the tool cost. Usually only 2% to 5% of the total cost. In addition, due to harmful substances in the cutting fluid, it causes harm to workers' health and causes environmental pollution. Therefore, its use has brought more and more problems. From these aspects, dry cutting has more advantages. The tools in dry cutting should have better high temperature resistance (thermosetting) and wear resistance. The current tool materials, such as new cemented carbide, ceramics, CBN and PCBN, have sufficient high temperature wear resistance. Used under dry cutting conditions. Moreover, modern cutting tool materials are more suitable for dry cutting when applied to high speed machining. Like CBN and advanced carbide grades, especially coated tool materials, cutting fluids at high speeds and temperatures are actually more efficient and long-lived. Dry cutting requirements for tools Dry cutting tool materials must have excellent thermoset and wear resistance to effectively withstand the high temperatures of the cutting process; lower friction coefficient to reduce the distance between the tool and the chip and the workpiece surface The friction suppresses the rise in cutting temperature; higher strength and impact resistance to withstand greater cutting forces and worse cutting conditions. To achieve dry cutting, tool materials with high heat resistance (thermoset) and wear resistance are especially necessary. Currently cubic boron nitride (CBN), polycrystalline cubic boron nitride (PCBN), diamond, polycrystalline diamond (PCD), ceramic (A12O3, Si3N4), cermet (CERAMIC), ultrafine grained carbide and hard Tool materials such as alloy coatings have been widely used in dry cutting. In the past two years, Iskar has developed a number of tool materials for dry cutting: IB90 and IB85. The CBN content is as high as 85% and 90%. The wear resistance and toughness of the insert are high, which can cope with the vibration caused by interrupted cutting. Recommended for high speed cutting of cast iron and interrupted cutting and roughing of hardened steel. The grades with low CBN content, IB55, IB50, CBN content of 50% and 55%, are more suitable for semi-finishing and finishing. IB10H is an ultra-fine grained CBN with higher wear resistance and toughness. It can be used for high-speed continuous cutting to obtain high surface quality; IB20H fine grain and medium grain CBN for continuous-slight intermittent cutting; Also, IB10HC, IB25HC and IB25HA are coated with TiN, Ti(C, N, O) and Ti(C, N) for various corresponding applications. The special tool coating coats the tool and is an important way to improve tool performance. The surface of the tough tool base is coated with a material with high heat resistance and wear resistance, which adds an insulation barrier between the tool and the chip during the cutting process, preventing heat transfer to the tool base and reducing the tool. The wear and heat generated and the friction coefficient between the tool/work surface are reduced to provide a certain degree of lubrication, so the coated tool is most suitable for dry cutting. For example, A12O3 is the basic component of alumina-based ceramics. A12O3 coating has good mechanical properties, excellent thermosetting and chemical stability. Therefore, A12O3 coated blades have good resistance to crater wear and low heat. The conductivity decreases with the increase of temperature. This characteristic can hinder the cutting heat from passing to the cutting edge of the tool during cutting, and prevent the cutting edge from being suddenly deformed due to plastic deformation. Iska passes the medium temperature. Chemically coated (MTCVD) α-TEC, optimized α phase with good oxidative stability and high thermal stability in A12O3, improved A12O3 multilayer coating. In general, coatings are divided into two categories: one is a hard coating, that is, coated with TiN, TiC, TiCN, TiA1N, A12O3, CBN, diamond, diamond-like DLC, nanomaterials, etc. The layer tool coating has high hardness and good wear resistance; the other type is “soft†coating, such as the anti-friction coating such as sulphur compound M0S2 or WS2 or TaS2, which significantly reduces the friction coefficient. Called "self-lubricating tool", this coated tool compensates for the lubrication of the non-cutting fluid to a certain extent, resists the rising cutting temperature, and is very suitable for dry cutting. Iskar's IC908, IC907, IC903 are hard-coated, they use ultra-fine grained carbide with good mechanical shock and thermal shock resistance as the matrix, coated with PVD coating process with lower friction coefficient. The high temperature material TiAlN has high oxidation resistance temperature and will produce TiAlN film during cutting. It has good oxidation resistance and the initial oxidation temperature is 700 °C ~ 800 °C, which is higher than the oxidation temperature of TiC, TiN and other coatings. TiAlN has higher hardness than TiN at high temperature, good thermal stability, and an oxide film generated at a high temperature. It can improve the friction between the tool and the workpiece/chip and reduce the heat generation. In addition, the thermal conductivity of the TiAlN coating is lower than that of the coating such as TiN, which can insulate the tool and make the tool bear higher during dry cutting. temperature. The PVD-TiAlN coating has a hardness comparable to that of TiCN and TiN, and the thermal stability temperature is higher than TiCN and TiN, reaching 1450 °C. With the increase of A1 content, the TiAlN coating has higher hardness, higher resistance to high temperature fracture, high hardness and wear resistance, and the oxidation temperature is unchanged. In the past two years, Iskar has used ultra-thin TiN and TiAlN to alternately coat the cutters. The coated tools have strong adhesion, high heat resistance and good wear resistance, and they gather TiN and TiAlN. The advantages of coatings such as TiNC, and then the post-treatment technology SUMO-TEC, further improve the toughness and wear resistance, reduce the surface friction coefficient, make the cutting area lower temperature, anti-cracking and anti-chip-forming properties Excellent, resulting in a more reliable and durable tool life when processing most of the material being processed, blade durability increased by 20% to 280%. The special design of the tool structure In terms of tool geometry, the dry cutting tool design should follow the "low cutting temperature" design principle. The tool structure design must consider the heat generated during the machining process as little as possible. Low cutting force and low friction. Conventional tools are not suitable for dry cutting. For this reason, dry cutting should optimize the tool geometry, which requires the tool to have a large rake angle and fit the appropriate cutting edge shape, such as the IsP's various milling inserts - PDR and -PDR HM groove type, with zero-degree small diamond blade and double positive rake angle design, which reduces the cutting force and strengthens the strength and heat capacity of the cutting edge. In order to reduce the heat of cutting, Iskar has reinforcing ribs on the rake face of the car blade, slot blade and milling insert to form a scaly cutting surface in the contact area. The contact area between the tool and the chip is greatly reduced, and most of the heat is reduced. It is taken away by the chips, the cutting temperature is greatly reduced compared with the ordinary blade, and the shear angle is also increased, so that the tool life is significantly improved. In addition, considering the maximum lubricity of the tool surface and preventing the formation of built-up edge, Iskar took the lead in the hard nickel layer and the Ti-containing layer, which greatly improved the hardness and lubricity of the surface of the tool body. The chip flute profile of the tool also needs to consider the "low cutting temperature" design principle to ensure the flow of low friction chips to reduce the friction between the tool and the chip during machining, which makes the chip removal quick and easy, and reduces heat accumulation. For this reason, Iss The card adopts the vertical blade structure in the field of milling cutters and slot cutters to avoid chipping and increase the chip evacuation space of the cutter body. The future dry machining of dry cutting involves not only tool materials, tool coatings, but also tool geometry, tool holder structure, machine tools, cutting volume, and machining methods. This requires the development of new tool materials, and the proper matching of tool materials with workpiece materials and the prevention of diffusion and bonding of tool materials and workpiece materials during dry cutting. Research on new tool materials focuses on superhard tool materials, cermets, ceramics, coatings, high-speed steels and hard alloys with excellent properties. Iskar attaches great importance to the development of coated tools, because the coated tools combine high hardness and wear resistance, high heat resistance, high toughness, high anti-blocking properties, high chemical stability and low The coefficient of friction, the development of dry cutting technology, relies heavily on the development of tool coating technology. In addition to studying the hardness, toughness and thermal stability of tool materials, there are also adaptability of different tool materials in dry cutting, the role, characteristics and performance of different materials in dry cutting. Tool geometry design, reasonable determination of blade shape and geometric parameters are very important for the full cutting performance of the tool, so Iska also continuously develops the blade shape with higher strength and more secure blade clamping method; consider the body The distribution of the mass is reasonably adjusted to make the body expand evenly and so on. For geometric parameters, we emphasize the principle of low cutting force and low cutting temperature. Dry cutting is a concrete manifestation of the production concept of environmentally clean, which not only reduces the production cost, but also promotes the advancement of cutting tool technology, and brings a new green manufacturing technology, which is the goal that the manufacturing industry will pursue.
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