End mills are one of the commonly used tools in milling and have a wide range of applications. They are mainly used to process planes, steps, grooves, curved surfaces and cavities of various shapes. Understanding the functions of different end mills is of great help in processing different materials. Choosing the right milling cutter can improve processing efficiency, processing accuracy and surface finish, and can also extend the service life of the tool.
Tool Materials Should Have Basic Properties
The selection of end mill material has a great impact on tool life, processing efficiency, processing quality and processing cost. End mills are subject to high pressure, high temperature, friction, impact and vibration during cutting. Therefore, end mill materials should have the following basic properties.
Hardness and wear resistance. The hardness of the end mill material must be higher than the hardness of the workpiece material, generally required to be above 60HRC. The higher the hardness of the end mill material, the better the wear resistance.
Strength and toughness. End mill materials should have high strength and toughness to withstand cutting force, impact and vibration, and prevent brittle fracture and chipping of the tool.
Heat resistance. End mill materials should have good heat resistance, be able to withstand high cutting temperatures, and have good antioxidant capacity.
Process performance and economy. End mill materials should have good forging performance, heat treatment performance, welding performance; grinding performance, etc., and should pursue high performance-price ratio.
Diamond End Mills
Diamond, as the hardest substance known in nature, has unparalleled hardness, wear resistance and thermal conductivity, making it very useful 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 an irreplaceable main force. Thanks to their excellent performance, diamond tools can achieve high efficiency, high stability and long life processing effects, becoming an indispensable and important tool in modern CNC processing.
Natural Diamond End Mill
Natural diamond is the hardest substance known in nature. Its hardness is far higher than other tool materials, and it can easily cope with the processing challenges of high-hardness materials. It has excellent wear resistance and can maintain sharpness even under high-speed cutting conditions, significantly extending the service life of the tool and reducing processing costs.
PCD Diamond End Mill
Although natural diamond end mills have an irreplaceable position in the field of ultra-precision machining, their high price limits their wide application. In order to overcome this problem, scientists invented polycrystalline diamond (PCD) tools, which are artificial diamond materials prepared by high temperature and high pressure synthesis technology. With its excellent cost-effectiveness, polycrystalline diamond end mills have gradually replaced natural diamond end mills in many fields and become the main force in the field of cutting and machining.
PCD end mills have better wear resistance than natural diamond end mills, and can maintain sharpness for a longer time under high-speed cutting conditions, extending the service life of the tool and improving machining efficiency. It can be used to process various non-ferrous metals and non-metallic materials, such as aluminum, copper, brass, plastics, ceramics, etc., and its application fields are very wide. Due to the large grain size of PCD end mills, their cutting edge sharpness is not as good as that of natural diamond tools, so the machining accuracy and surface finish are slightly inferior. Despite some shortcomings, with its price advantage and strong wear resistance, polycrystalline diamond tools have been widely used in the field of precision cutting of non-ferrous metals and non-metallic materials, becoming an indispensable tool material.
CVD Diamond End Mill
The emergence of CVD diamond has brought new changes to the field of cutting and processing. It combines the advantages of natural single crystal diamond and polycrystalline diamond (PCD), while overcoming some of their shortcomings, becoming an emerging force that cannot be ignored.
The hardness, wear resistance, thermal conductivity and other properties of CVD diamond are comparable to those of natural diamond, and even better in some aspects, and can meet the needs of high-strength and high-precision processing. CVD diamond can be used to process various non-ferrous metals, non-metallic materials, and composite materials, and its application field is very broad.
Cubic Boron Nitride End Mills
The second superhard material, cubic boron nitride (CBN), synthesized in a similar way to diamond manufacturing, is second only to diamond in hardness and thermal conductivity. It has excellent thermal stability and does not oxidize even when heated to 10000°C in the atmosphere. CBN has extremely stable chemical properties for ferrous metals and can be widely used in the processing of steel products.
The birth of CBN has brought revolutionary breakthroughs to the development of processing technology. With its excellent performance, it has become a sharp tool for processing hard materials such as steel and cast iron, and has played an irreplaceable role in various industrial fields.
CBN is the second hardest known material after diamond and can easily handle the processing challenges of high-hardness materials. It has excellent wear resistance and can maintain sharpness under high temperature and high speed cutting conditions, significantly extending the service life of the tool and reducing processing costs. Iron-based materials have good chemical inertness and will not react chemically with the workpiece during processing, avoiding phenomena such as tool sticking and tool holding, and improving processing accuracy and surface finish.
PCBN is a polycrystalline material sintered by fine CBN particles and binding phases (TiC, TiN, Al, Ti, etc.) under high temperature and high pressure. At present, PCBN is the highest artificial tool material after diamond, and is called super-hard end mill material together with diamond.
PCBN inherits the excellent properties of cubic boron nitride (CBN), while overcoming some of the shortcomings of CBN single crystals, showing strong advantages in the field of processing hard materials. The hardness of PCBN is second only to diamond, and it can easily process hard materials such as hardened steel, high-speed steel, and cast iron. PCBN has high thermal conductivity, which can effectively dissipate heat during the cutting process, reduce the heat load of the tool and workpiece, and improve processing stability.
Ceramic End Mills
Ceramic end mills, with their excellent performance, play an indispensable role in modern manufacturing. Their high hardness, good wear resistance, excellent heat resistance and chemical stability make them a powerful tool for high-speed cutting and difficult-to-process materials.
The hardness of ceramic end mills is second only to diamond, and they can easily process hard materials such as hardened steel, high-speed steel, and cast iron, effectively reducing the cost and time of grinding. They have good heat resistance and can maintain stable performance during high-temperature cutting to avoid affecting processing accuracy due to thermal deformation. At the same time, they have good chemical stability to various materials, will not react chemically with the workpiece, avoid sticking and holding, and improve processing accuracy and surface finish.
As an important tool material, ceramic end mills play an indispensable role in the field of high-speed finishing and semi-finishing. With their excellent performance, ceramic tools can efficiently process various cast irons, steels, copper alloys, graphite, engineering plastics and composite materials, bringing efficient and precise processing solutions to the manufacturing industry.
Carbide End Mills
Carbide end mills, especially indexable carbide end mills, play an indispensable role in the field of CNC machining. They are of various types and widely used. They have expanded from the original simple turning tools and face milling cutters to various precision, complex and forming tool fields, becoming an indispensable blade in modern manufacturing. Carbide end mills have the characteristics of high hardness, high wear resistance, high bending strength and toughness, good thermal stability, etc., and are widely used in metal cutting, non-metallic material processing and other fields.
Carbide end mills are made of extremely high hardness carbides (called hard phase) and metal binders (called bonding phases) by powder metallurgy. Their hardness is as high as 89-93HRA, which is much higher than high-speed steel. Even at a high temperature of 5400℃, the hardness can still be maintained at 82-87HRA, which is equivalent to the hardness of high-speed steel at room temperature.
The wear resistance of carbide end mills is dozens of times that of high-speed steel, and they can maintain good cutting performance under high temperature and high pressure conditions. It has high bending strength and toughness, is not easy to break, can withstand large cutting loads, and is suitable for high-strength and heavy-load processing occasions. It can still maintain hardness and strength at high temperatures, is not easy to produce thermal deformation, and can be used for high-speed cutting.
High Speed Steel End Mill
High Speed Steel (HSS) is a type of high alloy tool steel with alloy elements such as tungsten, molybdenum, chromium, and vanadium. Due to its excellent comprehensive performance, it plays an important role in the field of cutting processing.
General high speed steel
It can generally be divided into two categories: tungsten steel and tungsten-molybdenum steel. This type of high speed steel contains 0.7% to 0.9% (C). According to the different tungsten content in the steel, it can be divided into tungsten steel containing 12% or 18% W, tungsten-molybdenum steel containing 6% or 8% W, and molybdenum steel containing 2% or no W. General high speed steel has a certain hardness (63-66HRC) and wear resistance, high strength and toughness, good plasticity and processing technology, and is easy to forge, quench, anneal and grind. It can be made into various complex shapes of cutting tools.
High performance high speed steel
It is a new type of high speed steel developed on the basis of general high speed steel by adjusting the chemical composition and adding alloy elements to further improve its performance. Compared with general-purpose high-speed steel, high-performance high-speed steel has higher heat resistance, wear resistance and cutting performance, and can meet more demanding processing conditions.
High-carbon high-speed steel is a type of steel with increased carbon content based on high-speed steel. Compared with general-purpose high-speed steel, high-carbon high-speed steel has higher room temperature hardness and high temperature hardness. After quenching, the hardness of high-carbon high-speed steel can reach 67-71HRC, with good wear resistance, suitable for processing ordinary steel, cast iron and other materials.
High-vanadium high-speed steel is a high-speed steel characterized by high vanadium content. Due to its excellent wear resistance, it has an irreplaceable advantage in processing difficult-to-grind materials. The hardness of vanadium high-speed steel can reach 63-66HRC after quenching, and it can maintain a high hardness even at high temperatures. The wear resistance of high-vanadium high-speed steel is the highest among all high-speed steels, and it can withstand the wear of difficult-to-grind materials such as fiber, hard rubber, and plastic, and extend the service life of the tool.
The hardness of cobalt high-speed steel can reach 69-70HRC after quenching, and it can maintain a high hardness even at high temperatures, which is the highest hardness among all high-speed steels. It is suitable for processing difficult-to-process materials such as high-strength heat-resistant steel, high-temperature alloys, and titanium alloys. It can withstand the wear of difficult-to-process materials and extend the service life of the tool. Cobalt high-speed steel has moderate strength and toughness and can withstand certain cutting loads, but it is not suitable for large impacts.
Aluminum high-speed steel, also known as aluminum-containing super-hard high-speed steel, is a special type of steel that adds aluminum to high-speed steel. The hardness of aluminum high-speed steel can reach 66-68HRC after quenching, and it can maintain a hardness of more than 54HRC even at a high temperature of 600℃, with excellent hot hardness. The wear resistance of aluminum high-speed steel is better than that of general-purpose high-speed steel and high-carbon high-speed steel, and it can withstand the wear of difficult-to-process materials.
Nitrogen super-hard high-speed steel, also known as nitrogen-containing super-hard high-speed steel, is a special type of steel that adds nitrogen to high-speed steel. The addition of nitrogen gives nitrogen super-hard high-speed steel the same hardness, strength and toughness as cobalt high-speed steel, making it an ideal substitute for cobalt-containing high-speed steel. The advantages of nitrogen super-hard high-speed steel tools are high hardness, strength and toughness comparable to cobalt high-speed steel, good wear resistance, excellent cutting performance, and are suitable for low-speed cutting of difficult-to-process materials and low-speed high-precision processing. Compared with cobalt high-speed steel, nitrogen super-hard high-speed steel is cheaper.
When selecting end mill material, factors such as end mill service life, processing efficiency, processing quality and processing cost should be considered comprehensively to select the most suitable end mill material. First, the appropriate end mill material should be selected according to the properties of the processed material. Different processing technologies have different requirements for end mill materials. The requirements for processing accuracy and surface quality will also affect the selection of end mill material.
