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Summary of knowledge of high-speed cutting CNC tool materials

    Time:2016-07-29    Click:4337
    Polycrystalline diamond (PCD) tools
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    Polycrystalline diamond (PCD) tools PCD tools can realize high-speed processing of non-ferrous metals and non-metal wear-resistant materials. According to reports, the cutting speed of Si-Al alloys with PCD-inlaid drills can reach 300m/min~400m/min. PCD and cemented carbide composite drills use Al alloys, Mg alloys, composite materials FRP, graphite, and powder. For metallurgical blanks, compared with cemented carbide tools, the tool life is increased by 65 to 145 times; the speed υc of PCD face milling cutter processing alloys with high-strength Al alloy body is 3000m/min~4000m/min, and some can reach 7000m/min. In recent years, diamond film cutting tools (turning and milling inserts, twist drills, end mills, taps, etc.) have been developed abroad, with a life span of 10 to 140 times that of cemented carbide cutting tools.
    High-speed steel and carbide complex tools with excellent performance
    Gear cutters made of high-performance cobalt high-speed steel, powder metallurgy high-speed steel and cemented carbide can be used for high-speed cutting of gears. The gear hob made of new powder metallurgical materials made of cemented carbide powder and high-speed steel powder has a cutting speed of 150m/min~180m/min. After the TiAlN coating is processed, it can be used for high-speed dry cutting gears. When machining carbon structural steel and alloy steel with a twist drill made of fine-grained cemented carbide and coated with a wear-resistant, heat-resistant and lubricating coating and coolant, the cutting speed can reach 200m/min, and the cutting speed can reach 150m/ during dry cutting. min. When machining gray cast iron with a tap made of fine-grained cemented carbide, the cutting speed can reach 100m/min.
    Choose a tool reasonably according to the processing material
    How to correctly select the tool to process the corresponding workpiece material, thereby improving the processing productivity and reducing the production cost, is a very important issue. Each tool material has its specific processing range. Generally speaking, CBN, cermet, ceramic, and coated tools are suitable for processing ferrous metal materials such as steel. PCD tools are suitable for high-speed processing of non-ferrous metals such as aluminum, magnesium, copper and their alloys and non-metallic materials.
    According to the above table, a suitable tool material can be selected reasonably. Ceramic knives are suitable for processing various cast iron, steel parts and nickel-based superalloys. Different varieties and ceramic knives have different processing ranges. Al2O3-based ceramic knives have good wear resistance, heat resistance and high temperature chemical stability. For the processing of cast iron, steel and its alloys. Si3N4-based ceramic tools have good fracture toughness and thermal vibration resistance, and are suitable for intermittent machining of cast iron and alloy cast iron.
    Cermet tools not only have the hardness of ceramics, but also have the high strength of cemented carbide, good adhesion resistance and wear resistance, and low affinity with steel. It is suitable for medium and high-speed cutting die steel, when the cutting speed is as low as 750 m /min, cast iron parts can be processed.
    Diamond tools are suitable for processing non-metallic materials, non-ferrous metals and their alloys. Due to the poor thermal stability of diamond and strong chemical affinity with iron, PCD is not suitable for processing iron and steel materials. Diamond has a small friction coefficient and no affinity with non-ferrous metals. The chips are easy to flow out, and the thermal conductivity is high. The built-up edge is not easy to produce, and the processed surface quality is good. Most suitable for ultra-precision processing of non-ferrous metal materials, non-ferrous metals and non-metal materials, such as copper, aluminum and other non-ferrous metals and their alloys, ceramics, powder sintered cemented carbide, various fiber and particle reinforced composite materials, plastics , Rubber, graphite, glass and all kinds of wear-resistant wood (especially composite materials such as solid wood and plywood).
    Cubic boron nitride tools are suitable for processing various hardened steels, thermal spray materials, chilled cast irons, and cobalt-based and nickel-based materials above 35HRC. The higher the hardness of the processed materials, the better the performance of cubic boron nitride tools. Advantage. CBN tools with different CBN content have also been developed abroad to give full play to the cutting performance of CBN tools. According to reports, BN-10 can process gray cast iron at a speed of up to 2000m/min.
    The continuous update of tool materials has led to the development of high-speed and ultra-high-speed cutting. Various tool materials match the corresponding workpiece materials and have different cutting speed ranges. Coated tools will dominate the high-speed cutting field. Position; the advantages of ceramic tools will be developed more extensively; CBN and PCD will occupy an important position in high-speed cutting, and the application will become more and more extensive. Strengthening the research and development of high-speed cutting tool materials will be of great significance to the application and development of high-speed cutting technology.
    From the research of high-speed cutting mechanism, we can see that with the increase of cutting speed, the metal removal rate has been greatly improved, and the high strain rate of the material (about 1.67×105/s at the cutting speed of 500m/min, the cutting temperature (Up to 1400°C), the chip forming process and the various phenomena that occur on the contact surface between the tool and the workpiece are different from those under traditional cutting conditions. The hot hardness of the tool and the tool wear problem become the key. In order to achieve high-speed cutting, there must be tool materials and tool manufacturing technology suitable for high-speed cutting to support.
    The metal cutting tool materials currently used can be divided into nine types, including high-speed steel with the lowest cutting speed and worst wear resistance to polycrystalline diamond tools with the best high-speed performance. High-speed cutting also requires tool materials with good toughness, strong impact resistance and good wear resistance.
    Generally speaking, tools with lower performance, such as high-speed steel and uncoated cemented carbide, are widely used in ordinary cutting, but their high-speed performance is not good. High-performance tools, such as polycrystalline diamond tools, are the hardest of all tool materials. They have very high wear resistance and speed capabilities. Cutting heat has little effect on it. In high-speed processing of non-ferrous and non-metallic materials Time fully embodies its superiority. But it has poor impact resistance and poor thermal performance when cutting steel and cast iron materials. Because in high-speed cutting of ferrous metals, the carbon atoms in the tool material will diffuse to the workpiece, causing increased tool wear.
    Cemented carbide tools are the most widely used, accounting for 80% of the total sales of various tools. 90% of ordinary speed metal cutting uses cemented carbide tools. Cemented carbide has good impact toughness, but its high-speed performance is not good. In addition, high-speed cutting tools must have extremely high thermal hardness and chemical stability, and cemented carbide cannot meet the requirements in this regard.
    CBN tools have excellent heat resistance and can cut hard materials at high temperatures, but they are expensive and cannot process soft metal materials. The aluminum-based ceramic material with good chemical stability is just suitable for this kind of processing, but it lacks thermal hardness and cannot be used for high-speed processing.
    Focusing on the advantages of tool materials with different characteristics and developing new tool materials that have both impact resistance and high wear resistance are one of the main problems to be solved in the research of high-speed cutting tools. On the tool matrix material with relatively good anti-impact toughness, the surface coating of materials with good thermal hardness and wear resistance will produce new tools, which often have the advantages of two materials. This type of tool is used in high-speed cutting. Has a large scope of application.
    Under the guidance of this kind of thinking, new composite tools such as carbide-coated tools, CBN-coated tools and PCD-coated tools have appeared successively, which are suitable for high-speed cutting of different metal materials.
    Coated cemented carbide tools suitable for high-speed cutting. Due to the use of coating materials with good heat resistance and high hardness and multi-layer coating technology, the coated cemented carbide tools have a large cutting range and long life. The performance is much better than uncoated cemented carbide. Therefore, coated cemented carbide has a tendency to replace ordinary non-coated cemented carbide.
    Tool coating technology can be used not only on hardened alloy tools, but also on other tool materials, such as cermets and ceramics.
    Ceramic tools are also tools that can be used for high-speed cutting, and are an important part of the research and development of tool materials in recent years. The whisker-reinforced ceramic cutting tool is a special material cutting tool. It is very suitable for high-speed machining due to its good impact resistance and strong thermal shock resistance.
    Another problem to be solved by high-speed cutting tools is to grind or press out a certain geometrical chip breaker on the blade in order to achieve chip breaking and control the chip direction. This is also an important technology to improve processing efficiency and improve tool durability.
    High-speed cutting tools should have excellent impact toughness and thermal shock resistance, better heat resistance, wear resistance and chemical stability, as well as better chip breaking effect, and be adapted to a larger metal cutting range.
    High-speed cutting development trend
    The development trends of high-speed cutting mainly include:
    (1) Develop and develop a new generation of high-speed and high-power machine tools to further improve and enhance spindle performance.
    (2) New high-wear and heat-resistant tool materials need to be developed, and high-speed tool structures need to be further improved. Because high-speed cutting tools directly determine the benefits, quality and safety of high-speed cutting, it is the basis for the promotion and implementation of high-speed cutting technology.
    (3) Develop and promote new dry cutting and hard cutting processes. In recent years, in the process of developing high-speed cutting abroad, new processes of dry cutting and hard cutting (ie cutting hardened workpieces) have been developed and applied. Because thousand cutting has the effect of protecting the environment, hard cutting can replace the role of grinding to improve work efficiency, and has obtained new developments, but both types of cutting require high-performance tool materials.
    Therefore, it is not difficult to know that high-speed cutting tool materials will play an irreplaceable role in my country's socialist construction.
     
     
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