The combination of advanced processing equipment and high-performance CNC cutting tools can give full play to its due performance and achieve good economic benefits. With the rapid development of cutting tool materials, various new cutting tool materials have greatly improved their physical, mechanical properties and cutting performance, and their application range has also continued to expand.
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1. Tool materials should have basic properties
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The choice of tool material has a great influence on tool life, processing efficiency, processing quality and processing cost. When the tool is cutting, it must bear the effects of high pressure, high temperature, friction, shock and vibration. Therefore, the tool material should have the following basic properties:
(1) Hardness and wear resistance. The hardness of the tool material must be higher than that of the workpiece material, generally above 60HRC. The harder the tool material, the better the wear resistance.
(2) Strength and toughness. Tool materials should have high strength and toughness to withstand cutting forces, shocks and vibrations, and prevent brittle fracture and chipping of tools.
(3) Heat resistance. The heat resistance of the tool material is better, it can withstand high cutting temperature, and it has good oxidation resistance.
(4) Process performance and economy. Tool materials should have good forging performance, heat treatment performance, welding performance, grinding performance, etc., and should pursue high performance-price ratio.
2. Types, properties, characteristics and applications of tool materials
1. Types, properties and characteristics of diamond tool materials and tool applications
Diamond is an allotrope of carbon, and it is the hardest material found in nature. Diamond tools have high hardness, high wear resistance and high thermal conductivity, and are widely used in the processing of non-ferrous metals and non-metallic materials. Especially in the high-speed cutting of aluminum and silicon-aluminum alloys, diamond tools are the main types of cutting tools that are difficult to replace. Diamond tools that can achieve high efficiency, high stability, and long-life machining are indispensable and important tools in modern CNC machining.
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⑴ Types of diamond tools
① Natural diamond tool: Natural diamond has been used as a cutting tool for hundreds of years. The natural single crystal diamond tool has been finely ground, and the cutting edge can be ground extremely sharp. The cutting edge radius can reach 0.002μm, which can realize ultra-thin cutting and can It is a recognized, ideal and irreplaceable ultra-precision machining tool for processing extremely high workpiece precision and extremely low surface roughness.
② PCD diamond tool: Natural diamond is expensive, and polycrystalline diamond (PCD) is widely used in cutting. Since the early 1970s, polycrystalline diamond (Polycrystauine diamond, PCD for short) was developed After success, natural diamond tools have been replaced by artificial polycrystalline diamond in many occasions. PCD raw materials are rich in sources, and its price is only a few tenths to one tenth of natural diamonds.
PCD tools cannot grind extremely sharp edges, and the surface quality of the processed workpieces is not as good as that of natural diamond. It is not convenient to manufacture PCD inserts with chip breakers in the industry. Therefore, PCD can only be used for fine cutting of non-ferrous metals and non-metals, and it is difficult to achieve ultra-precision mirror cutting.
③ CVD diamond tools: From the late 1970s to the early 1980s, CVD diamond technology appeared in Japan. CVD diamond refers to the synthesis of diamond film on heterogeneous substrates (such as cemented carbide, ceramics, etc.) by chemical vapor deposition (CVD). CVD diamond has exactly the same structure and characteristics as natural diamond.
The performance of CVD diamond is very close to that of natural diamond, and it has the advantages of natural single crystal diamond and polycrystalline diamond (PCD), and overcomes their shortcomings to a certain extent.
⑵ Performance characteristics of diamond tools
① Extremely high hardness and wear resistance: Natural diamond is the hardest substance found in nature. Diamond has extremely high wear resistance. When processing high-hardness materials, the life of diamond tools is 10 to 100 times that of cemented carbide tools, or even hundreds of times.
② It has a very low coefficient of friction: the coefficient of friction between diamond and some non-ferrous metals is lower than that of other cutting tools, the coefficient of friction is low, the deformation during processing is small, and the cutting force can be reduced.
③ The cutting edge is very sharp: the cutting edge of diamond tools can be sharpened, and the natural single crystal diamond tool can be as high as 0.002-0.008μm, which can be used for ultra-thin cutting and ultra-precision machining.
④ Has high thermal conductivity: diamond has high thermal conductivity and thermal diffusivity, cutting heat is easily dissipated, and the temperature of the cutting part of the tool is low.
⑤ Low thermal expansion coefficient: The thermal expansion coefficient of diamond is several times smaller than that of cemented carbide, and the change in tool size caused by cutting heat is very small, which is especially important for precision and ultra-precision machining that requires high dimensional accuracy.
⑶ Application of diamond tools
Diamond tools are mostly used for fine cutting and boring of non-ferrous metals and non-metallic materials at high speed. It is suitable for processing various wear-resistant non-metals, such as FRP powder metallurgy blanks, ceramic materials, etc.; various wear-resistant non-ferrous metals, such as various silicon-aluminum alloys; various non-ferrous metal finishing processing.
The disadvantage of diamond tools is that they have poor thermal stability. When the cutting temperature exceeds 700°C to 800°C, it will completely lose its hardness; in addition, it is not suitable for cutting ferrous metals, because diamond (carbon) is easy to bond with iron at high temperatures. The atomic action converts the carbon atoms into a graphite structure, and the tool is easily damaged.
2. Types, properties and characteristics of cubic boron nitride tool materials and tool applications
Cubic boron nitride (CBN), the second superhard material synthesized by a method similar to that of diamond, is second only to diamond in terms of hardness and thermal conductivity. It has excellent thermal stability and can be heated to 10,000°C in the atmosphere. Oxidation does not occur. CBN has extremely stable chemical properties for ferrous metals and can be widely used in the processing of steel products.
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⑴ Types of cubic boron nitride cutting tools
Cubic boron nitride (CBN) is a substance that does not exist in nature. It can be divided into single crystal and polycrystalline, that is, CBN single crystal and polycrystalline cubic boron nitride (Polycrystalline cubic bornnitride, referred to as PCBN). CBN is one of the isomers of boron nitride (BN), and its structure is similar to that of diamond.
PCBN (polycrystalline cubic boron nitride) is a polycrystalline material that sinters fine CBN materials through a bonding phase (TiC, TiN, Al, Ti, etc.) under high temperature and high pressure. Diamond tool material, it and diamond collectively referred to as superhard tool material. PCBN is mainly used to make knives or other tools.
PCBN tools can be divided into integral PCBN inserts and PCBN composite inserts sintered with cemented carbide.
PCBN composite inserts are made by sintering a layer of PCBN with a thickness of 0.5 to 1.0mm on a cemented carbide with good strength and toughness. Its performance has both good toughness and high hardness and wear resistance. The problems of low bending strength and welding difficulties of CBN inserts are solved.
⑵ Main properties and characteristics of cubic boron nitride
Although the hardness of cubic boron nitride is slightly inferior to diamond, it is much higher than other high hardness materials. The outstanding advantage of CBN is that its thermal stability is much higher than that of diamond, which can reach above 1200°C (700-800°C for diamond). reaction. The main performance characteristics of cubic boron nitride are as follows.
① High hardness and wear resistance: The crystal structure of CBN is similar to that of diamond, and has similar hardness and strength to diamond. PCBN is especially suitable for processing high-hardness materials that could only be ground before, and can obtain better surface quality of workpieces.
② High thermal stability: The heat resistance of CBN can reach 1400-1500°C, which is almost 1 times higher than that of diamond (700-800°C). PCBN tools can cut high-temperature alloys and hardened steels at a speed 3 to 5 times higher than that of cemented carbide tools.
③Excellent chemical stability: It does not have chemical interaction with iron-based materials at 1200-1300°C, and it will not wear out as sharply as diamond, and it can still maintain the hardness of cemented carbide at this time; PCBN tools are suitable for cutting hardened steel Parts and chilled cast iron, can be widely used in high-speed cutting of cast iron.
④ Good thermal conductivity: Although the thermal conductivity of CBN is not as good as that of diamond, the thermal conductivity of PCBN is second only to diamond among various tool materials, and is much higher than that of high-speed steel and cemented carbide.
⑤ Low coefficient of friction: A low coefficient of friction can reduce the cutting force during cutting, reduce the cutting temperature, and improve the quality of the machined surface.
⑶ Cubic boron nitride tool application
Cubic boron nitride is suitable for finishing various difficult-to-cut materials such as hardened steel, hard cast iron, high-temperature alloy, hard alloy, and surface spraying materials. The machining accuracy can reach IT5 (the hole is IT6), and the surface roughness can be as small as Ra1.25～0.20μm.
Cubic boron nitride tool material has poor toughness and bending strength. Therefore, cubic boron nitride turning tools are not suitable for rough machining with low speed and high impact load; Severe built-up edge will occur in the case of metal, which will deteriorate the machined surface.
3. Types, properties and characteristics of ceramic tool materials and tool applications
Ceramic cutting tools have the characteristics of high hardness, good wear resistance, excellent heat resistance and chemical stability, and are not easy to bond with metal. Ceramic cutting tools occupy a very important position in CNC machining. Ceramic cutting tools have become one of the main cutting tools for high-speed cutting and processing of difficult-to-machine materials. Ceramic cutting tools are widely used in high-speed cutting, dry cutting, hard cutting and cutting of difficult-to-machine materials. Ceramic knives can efficiently process high-hard materials that traditional knives cannot process at all, and realize "replacing grinding with a car"; the optimal cutting speed of ceramic knives can be 2 to 10 times higher than that of cemented carbide knives, thus greatly improving the production efficiency of cutting processing The main raw material used in ceramic tool materials is the most abundant element in the earth's crust. Therefore, the popularization and application of ceramic tools is of great significance to improve productivity, reduce processing costs, and save strategic precious metals, and will also greatly promote the development of cutting technology. progress.
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⑴ Types of ceramic tool materials
The types of ceramic tool materials can generally be divided into three categories: alumina-based ceramics, silicon nitride-based ceramics, and composite silicon nitride-alumina-based ceramics. Among them, alumina-based and silicon nitride-based ceramic tool materials are the most widely used. The performance of silicon nitride-based ceramics is superior to that of alumina-based ceramics.
⑵ Performance and characteristics of ceramic cutting tools
The performance characteristics of ceramic cutting tools are as follows:
① High hardness and good wear resistance: Although the hardness of ceramic tools is not as high as that of PCD and PCBN, it is much higher than that of cemented carbide and high-speed steel tools, reaching 93-95HRA. Ceramic tools can process high-hardness materials that are difficult to process with traditional tools, and are suitable for high-speed cutting and hard cutting.
② High temperature resistance and good heat resistance: Ceramic tools can still cut at high temperatures above 1200 °C. Ceramic knives have good high-temperature mechanical properties, and the oxidation resistance of A12O3 ceramic knives is particularly good. Even if the cutting edge is in a red-hot state, it can be used continuously. Therefore, ceramic tools can achieve dry cutting, which can save cutting fluid.
③ Good chemical stability: ceramic cutting tools are not easy to bond with metal, and are corrosion-resistant and chemically stable, which can reduce the bonding wear of cutting tools.
④ Low coefficient of friction: The affinity between ceramic cutting tools and metal is small, and the coefficient of friction is low, which can reduce cutting force and cutting temperature.
⑶ Application of ceramic knives
Ceramics are one of the tool materials mainly used for high-speed finishing and semi-finishing. Ceramic cutting tools are suitable for cutting all kinds of cast iron (gray cast iron, ductile iron, malleable cast iron, chilled cast iron, high alloy wear-resistant cast iron) and steel (carbon structural steel, alloy structural steel, high strength steel, high manganese steel, quenched steel etc.), can also be used to cut copper alloys, graphite, engineering plastics and composite materials.
There are problems of low bending strength and poor impact toughness in the performance of ceramic tool materials, which are not suitable for cutting under low speed and impact load.
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4. Properties and Characteristics of Coated Cutting Tool Materials and Application of Cutting Tools
Coating the tool is one of the important ways to improve the performance of the tool. The emergence of coated cutting tools has made a major breakthrough in the cutting performance of cutting tools. The coated tool is coated with one or more layers of refractory compound with good wear resistance on the tougher tool body, which combines the tool substrate with the hard coating, so that the performance of the tool is greatly improved. Coated cutting tools can improve processing efficiency, improve processing accuracy, prolong tool life and reduce processing costs.
About 80% of the cutting tools used in new CNC machine tools use coated tools. Coated cutting tools will be the most important tool variety in the field of CNC machining in the future.
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⑴ Types of coated tools
According to different coating methods, coated tools can be divided into chemical vapor deposition (CVD) coated tools and physical vapor deposition (PVD) coated tools. Coated carbide tools generally use chemical vapor deposition, and the deposition temperature is around 1000 °C. Coated high-speed steel tools generally use physical vapor deposition, and the deposition temperature is about 500 °C;
According to the different substrate materials of coated tools, coated tools can be divided into carbide coated tools, high-speed steel coated tools, and coated tools on ceramics and superhard materials (diamond and cubic boron nitride).
According to the nature of the coating material, coated tools can be divided into two categories, namely "hard" coated tools and 'soft' coated tools. The main goals pursued by "hard" coated tools are high hardness and wear resistance Its main advantages are high hardness and good wear resistance, typically TiC and TiN coatings. The goal pursued by "soft" coating tools is a low coefficient of friction, also known as self-lubricating tools, and its friction with the workpiece material The coefficient is very low, only about 0.1, which can reduce bonding, reduce friction, reduce cutting force and cutting temperature.
Recently developed a nano-coating (Nanoeoating) tool. This coated tool can use different combinations of various coating materials (such as metal/metal, metal/ceramic, ceramic/ceramic, etc.) to meet different functional and performance requirements. A properly designed nano-coating can make the tool material have excellent anti-friction and anti-wear functions and self-lubricating properties, which is suitable for high-speed dry cutting.
⑵ Characteristics of coated tools
The performance characteristics of coated tools are as follows:
① Good mechanical and cutting performance: Coated tools combine the excellent properties of the base material and the coating material, which not only maintains the good toughness and high strength of the base
The combination of advanced processing equipment and high-performance CNC cutting tools can give full play to its due performance and achieve good economic benefits. With the rapid development of cutting tool materials, various new cutting tool materials have greatly improved their physical, mechanical properties and cutting performance, and their application range has also continued to expand.
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1. Tool materials should have basic properties
the
The choice of tool material has a great influence on tool life, processing efficiency, processing quality and processing cost. When the tool is cutting, it must bear the effects of high pressure, high temperature, friction, shock and vibration. Therefore, the tool material should have the following basic properties:
(1) Hardness and wear resistance. The hardness of the tool material must be higher than that of the workpiece material, generally above 60HRC. The harder the tool material, the better the wear resistance.
(2) Strength and toughness. Tool materials should have high strength and toughness to withstand cutting forces, shocks and vibrations, and prevent brittle fracture and chipping of tools.
(3) Heat resistance. The heat resistance of the tool material is better, it can withstand high cutting temperature, and it has good oxidation resistance.
(4) Process performance and economy. Tool materials should have good forging performance, heat treatment performance, welding performance, grinding performance, etc., and should pursue high performance-price ratio.
2. Types, properties, characteristics and applications of tool materials
1. Types, properties and characteristics of diamond tool materials and tool applications
Diamond is an allotrope of carbon, and it is the hardest material found in nature. Diamond tools have high hardness, high wear resistance and high thermal conductivity, and are widely used in the processing of non-ferrous metals and non-metallic materials. Especially in the high-speed cutting of aluminum and silicon-aluminum alloys, diamond tools are the main types of cutting tools that are difficult to replace. Diamond tools that can achieve high efficiency, high stability, and long-life machining are indispensable and important tools in modern CNC machining.
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⑴ Types of diamond tools
① Natural diamond tool: Natural diamond has been used as a cutting tool for hundreds of years. The natural single crystal diamond tool has been finely ground, and the cutting edge can be ground extremely sharp. The cutting edge radius can reach 0.002μm, which can realize ultra-thin cutting and can It is a recognized, ideal and irreplaceable ultra-precision machining tool for processing extremely high workpiece precision and extremely low surface roughness.
② PCD diamond tool: Natural diamond is expensive, and polycrystalline diamond (PCD) is widely used in cutting. Since the early 1970s, polycrystalline diamond (Polycrystauine diamond, PCD for short) was developed After success, natural diamond tools have been replaced by artificial polycrystalline diamond in many occasions. PCD raw materials are rich in sources, and its price is only a few tenths to one tenth of natural diamonds.
PCD tools cannot grind extremely sharp edges, and the surface quality of the processed workpieces is not as good as that of natural diamond. It is not convenient to manufacture PCD inserts with chip breakers in the industry. Therefore, PCD can only be used for fine cutting of non-ferrous metals and non-metals, and it is difficult to achieve ultra-precision mirror cutting.
③ CVD diamond tools: From the late 1970s to the early 1980s, CVD diamond technology appeared in Japan. CVD diamond refers to the synthesis of diamond film on heterogeneous substrates (such as cemented carbide, ceramics, etc.) by chemical vapor deposition (CVD). CVD diamond has exactly the same structure and characteristics as natural diamond.
The performance of CVD diamond is very close to that of natural diamond, and it has the advantages of natural single crystal diamond and polycrystalline diamond (PCD), and overcomes their shortcomings to a certain extent.
⑵ Performance characteristics of diamond tools
① Extremely high hardness and wear resistance: Natural diamond is the hardest substance found in nature. Diamond has extremely high wear resistance. When processing high-hardness materials, the life of diamond tools is 10 to 100 times that of cemented carbide tools, or even hundreds of times.
② It has a very low coefficient of friction: the coefficient of friction between diamond and some non-ferrous metals is lower than that of other cutting tools, the coefficient of friction is low, the deformation during processing is small, and the cutting force can be reduced.
③ The cutting edge is very sharp: the cutting edge of diamond tools can be sharpened, and the natural single crystal diamond tool can be as high as 0.002-0.008μm, which can be used for ultra-thin cutting and ultra-precision machining.
④ Has high thermal conductivity: diamond has high thermal conductivity and thermal diffusivity, cutting heat is easily dissipated, and the temperature of the cutting part of the tool is low.
⑤ Low thermal expansion coefficient: The thermal expansion coefficient of diamond is several times smaller than that of cemented carbide, and the change in tool size caused by cutting heat is very small, which is especially important for precision and ultra-precision machining that requires high dimensional accuracy.
⑶ Application of diamond tools
Diamond tools are mostly used for fine cutting and boring of non-ferrous metals and non-metallic materials at high speed. It is suitable for processing various wear-resistant non-metals, such as FRP powder metallurgy blanks, ceramic materials, etc.; various wear-resistant non-ferrous metals, such as various silicon-aluminum alloys; various non-ferrous metal finishing processing.
The disadvantage of diamond tools is that they have poor thermal stability. When the cutting temperature exceeds 700°C to 800°C, it will completely lose its hardness; in addition, it is not suitable for cutting ferrous metals, because diamond (carbon) is easy to bond with iron at high temperatures. The atomic action converts the carbon atoms into a graphite structure, and the tool is easily damaged.
2. Types, properties and characteristics of cubic boron nitride tool materials and tool applications
Cubic boron nitride (CBN), the second superhard material synthesized by a method similar to that of diamond, is second only to diamond in terms of hardness and thermal conductivity. It has excellent thermal stability and can be heated to 10,000°C in the atmosphere. Oxidation does not occur. CBN has extremely stable chemical properties for ferrous metals and can be widely used in the processing of steel products.
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⑴ Types of cubic boron nitride cutting tools
Cubic boron nitride (CBN) is a substance that does not exist in nature. It can be divided into single crystal and polycrystalline, that is, CBN single crystal and polycrystalline cubic boron nitride (Polycrystalline cubic bornnitride, referred to as PCBN). CBN is one of the isomers of boron nitride (BN), and its structure is similar to that of diamond.
PCBN (polycrystalline cubic boron nitride) is a polycrystalline material that sinters fine CBN materials through a bonding phase (TiC, TiN, Al, Ti, etc.) under high temperature and high pressure. Diamond tool material, it and diamond collectively referred to as superhard tool material. PCBN is mainly used to make knives or other tools.
PCBN tools can be divided into integral PCBN inserts and PCBN composite inserts sintered with cemented carbide.
PCBN composite inserts are made by sintering a layer of PCBN with a thickness of 0.5 to 1.0mm on a cemented carbide with good strength and toughness. Its performance has both good toughness and high hardness and wear resistance. The problems of low bending strength and welding difficulties of CBN inserts are solved.
⑵ Main properties and characteristics of cubic boron nitride
Although the hardness of cubic boron nitride is slightly inferior to diamond, it is much higher than other high hardness materials. The outstanding advantage of CBN is that its thermal stability is much higher than that of diamond, which can reach above 1200°C (700-800°C for diamond). reaction. The main performance characteristics of cubic boron nitride are as follows.
① High hardness and wear resistance: The crystal structure of CBN is similar to that of diamond, and has similar hardness and strength to diamond. PCBN is especially suitable for processing high-hardness materials that could only be ground before, and can obtain better surface quality of workpieces.
② High thermal stability: The heat resistance of CBN can reach 1400-1500°C, which is almost 1 times higher than that of diamond (700-800°C). PCBN tools can cut high-temperature alloys and hardened steels at a speed 3 to 5 times higher than that of cemented carbide tools.
③Excellent chemical stability: It does not have chemical interaction with iron-based materials at 1200-1300°C, and it will not wear out as sharply as diamond, and it can still maintain the hardness of cemented carbide at this time; PCBN tools are suitable for cutting hardened steel Parts and chilled cast iron, can be widely used in high-speed cutting of cast iron.
④ Good thermal conductivity: Although the thermal conductivity of CBN is not as good as that of diamond, the thermal conductivity of PCBN is second only to diamond among various tool materials, and is much higher than that of high-speed steel and cemented carbide.
⑤ Low coefficient of friction: A low coefficient of friction can reduce the cutting force during cutting, reduce the cutting temperature, and improve the quality of the machined surface.
⑶ Cubic boron nitride tool application
Cubic boron nitride is suitable for finishing various difficult-to-cut materials such as hardened steel, hard cast iron, high-temperature alloy, hard alloy, and surface spraying materials. The machining accuracy can reach IT5 (the hole is IT6), and the surface roughness can be as small as Ra1.25～0.20μm.
Cubic boron nitride tool material has poor toughness and bending strength. Therefore, cubic boron nitride turning tools are not suitable for rough machining with low speed and high impact load; Severe built-up edge will occur in the case of metal, which will deteriorate the machined surface.
3. Types, properties and characteristics of ceramic tool materials and tool applications
Ceramic cutting tools have the characteristics of high hardness, good wear resistance, excellent heat resistance and chemical stability, and are not easy to bond with metal. Ceramic cutting tools occupy a very important position in CNC machining. Ceramic cutting tools have become one of the main cutting tools for high-speed cutting and processing of difficult-to-machine materials. Ceramic cutting tools are widely used in high-speed cutting, dry cutting, hard cutting and cutting of difficult-to-machine materials. Ceramic knives can efficiently process high-hard materials that traditional knives cannot process at all, and realize "replacing grinding with a car"; the optimal cutting speed of ceramic knives can be 2 to 10 times higher than that of cemented carbide knives, thus greatly improving the production efficiency of cutting processing The main raw material used in ceramic tool materials is the most abundant element in the earth's crust. Therefore, the popularization and application of ceramic tools is of great significance to improve productivity, reduce processing costs, and save strategic precious metals, and will also greatly promote the development of cutting technology. progress.
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⑴ Types of ceramic tool materials
The types of ceramic tool materials can generally be divided into three categories: alumina-based ceramics, silicon nitride-based ceramics, and composite silicon nitride-alumina-based ceramics. Among them, alumina-based and silicon nitride-based ceramic tool materials are the most widely used. The performance of silicon nitride-based ceramics is superior to that of alumina-based ceramics.
⑵ Performance and characteristics of ceramic cutting tools
The performance characteristics of ceramic cutting tools are as follows:
① High hardness and good wear resistance: Although the hardness of ceramic tools is not as high as that of PCD and PCBN, it is much higher than that of cemented carbide and high-speed steel tools, reaching 93-95HRA. Ceramic tools can process high-hardness materials that are difficult to process with traditional tools, and are suitable for high-speed cutting and hard cutting.
② High temperature resistance and good heat resistance: Ceramic tools can still cut at high temperatures above 1200 °C. Ceramic knives have good high-temperature mechanical properties, and the oxidation resistance of A12O3 ceramic knives is particularly good. Even if the cutting edge is in a red-hot state, it can be used continuously. Therefore, ceramic tools can achieve dry cutting, which can save cutting fluid.
③ Good chemical stability: ceramic cutting tools are not easy to bond with metal, and are corrosion-resistant and chemically stable, which can reduce the bonding wear of cutting tools.
④ Low coefficient of friction: The affinity between ceramic cutting tools and metal is small, and the coefficient of friction is low, which can reduce cutting force and cutting temperature.
⑶ Application of ceramic knives
Ceramics are one of the tool materials mainly used for high-speed finishing and semi-finishing. Ceramic cutting tools are suitable for cutting all kinds of cast iron (gray cast iron, ductile iron, malleable cast iron, chilled cast iron, high alloy wear-resistant cast iron) and steel (carbon structural steel, alloy structural steel, high strength steel, high manganese steel, quenched steel etc.), can also be used to cut copper alloys, graphite, engineering plastics and composite materials.
There are problems of low bending strength and poor impact toughness in the performance of ceramic tool materials, which are not suitable for cutting under low speed and impact load.
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4. Properties and Characteristics of Coated Cutting Tool Materials and Application of Cutting Tools
Coating the tool is one of the important ways to improve the performance of the tool. The emergence of coated cutting tools has made a major breakthrough in the cutting performance of cutting tools. The coated tool is coated with one or more layers of refractory compound with good wear resistance on the tougher tool body, which combines the tool substrate with the hard coating, so that the performance of the tool is greatly improved. Coated cutting tools can improve processing efficiency, improve processing accuracy, prolong tool life and reduce processing costs.
About 80% of the cutting tools used in new CNC machine tools use coated tools. Coated cutting tools will be the most important tool variety in the field of CNC machining in the future.
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⑴ Types of coated tools
According to different coating methods, coated tools can be divided into chemical vapor deposition (CVD) coated tools and physical vapor deposition (PVD) coated tools. Coated carbide tools generally use chemical vapor deposition, and the deposition temperature is around 1000 °C. Coated high-speed steel tools generally use physical vapor deposition, and the deposition temperature is about 500 °C;
According to the different substrate materials of coated tools, coated tools can be divided into carbide coated tools, high-speed steel coated tools, and coated tools on ceramics and superhard materials (diamond and cubic boron nitride).
According to the nature of the coating material, coated tools can be divided into two categories, namely "hard" coated tools and 'soft' coated tools. The main goals pursued by "hard" coated tools are high hardness and wear resistance Its main advantages are high hardness and good wear resistance, typically TiC and TiN coatings. The goal pursued by "soft" coating tools is a low coefficient of friction, also known as self-lubricating tools, and its friction with the workpiece material The coefficient is very low, only about 0.1, which can reduce bonding, reduce friction, reduce cutting force and cutting temperature.
Recently developed a nano-coating (Nanoeoating) tool. This coated tool can use different combinations of various coating materials (such as metal/metal, metal/ceramic, ceramic/ceramic, etc.) to meet different functional and performance requirements. A properly designed nano-coating can make the tool material have excellent anti-friction and anti-wear functions and self-lubricating properties, which is suitable for high-speed dry cutting.
⑵ Characteristics of coated tools
The performance characteristics of coated tools are as follows:
① Good mechanical and cutting performance: Coated tools combine the excellent properties of the base material and the coating material, which not only maintains the good toughness and high strength of the base
