A good horse needs a good saddle. Using advanced CNC machines is useless if the wrong cutting tools are used! Choosing the right cutting tool material greatly affects tool life, efficiency, quality, and cost. At Samshion, we combine years of prototyping and CNC machining expertise to help clients choose the right tools and materials.
What Are the Basic Properties of Cutting Tool Materials?
Selecting the right cutting tool material impacts tool life, efficiency, quality, and cost. Cutting tools must withstand high pressure, temperature, friction, impact, and vibration. Samshion team always consider these factors to recommend optimal solutions:
(1) Hardness and wear resistance. The hardness of the cutting tool material must be higher than the hardness of the workpiece material, generally required to be above 60HRC. The higher the hardness of the cutting tool material, the better the wear resistance.
(2) Strength and toughness. The cutting tool material should have high strength and toughness to withstand cutting force, impact and vibration, and prevent brittle fracture and chipping of the cutting tool.
(3) Heat resistance. The tool material should have good heat resistance, be able to withstand high cutting temperatures, and have good antioxidant capacity.
(4) Process performance and economy. The tool material should have good forging performance, heat treatment performance, welding performance, grinding performance, etc., and should pursue a high performance-price ratio.
What Are the Different Tool Materials and Their Applications?
Diamond Tools – Why Are They Irreplaceable for Non-Ferrous Materials?
Samshion uses diamond tools in our prototypes for ultra-precision cutting of aluminum alloys, fiberglass, ceramics, and other non-ferrous materials. Cause diamond is an allotrope of carbon and is the hardest material discovered 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 cutting tool variety that is difficult to replace. Diamond tools that can achieve high efficiency, high stability, and long life processing are an indispensable and important tool in modern CNC processing.
Which Diamond Tool Types Are Preferred by Samshion for Precision CNC Projects?
① Natural Diamond Tools: Natural diamond has been used as a cutting tool for centuries. Natural single-crystal diamond tools, after fine grinding, can achieve an extremely sharp cutting edge with a cutting edge radius of up to 0.002μm. They are capable of ultra-thin cutting, producing extremely high workpiece precision and extremely low surface roughness. They are recognized as ideal and irreplaceable ultra-precision machining tools.
② PCD diamond tools: Natural diamonds are expensive, and polycrystalline diamond (PCD) is still widely used in cutting processes. Since the early 1970s, when PCD inserts, produced using high-temperature and high-pressure synthesis technology, were successfully developed, natural diamond tools have been replaced by synthetic PCD in many applications. PCD raw materials are abundant, and its price is only a few tenths to a dozen times that of natural diamond. However, PCD tools cannot produce extremely sharp cutting edges, and the surface quality of the workpieces processed is inferior to that of natural diamond. Currently, PCD inserts with chip breakers cannot be easily manufactured in the industry. Therefore, PCD can only be used for precision cutting of non-ferrous metals and non-metals, and it is difficult to achieve ultra-precision mirror cutting.
③ CVD diamond tools: CVD diamond technology emerged in Japan in the late 1970s and early 1980s. CVD diamond refers to the process of synthesizing a diamond film on a heterogeneous substrate (such as cemented carbide or ceramic) using chemical vapor deposition (CVD). CVD diamond has the exact same structure and properties as natural diamond. The performance of CVD diamond closely matches that of natural diamond, combining the advantages of natural single-crystal diamond and polycrystalline diamond (PCD), while also overcoming their shortcomings to a certain extent.
What Are the Performance Characteristics of Diamond Tools?
It is used in Samshion CNC machining for hardened steels, cast iron, and high-temperature alloys. Here are its advantages:
① Extremely High Hardness and Wear Resistance: Natural diamond is the hardest substance discovered in nature. Diamond possesses extremely high wear resistance. When machining high-hardness materials, the lifespan of diamond tools can be 10 to 100 times, or even several hundred times, longer than that of carbide tools.
② Very Low Friction Coefficient: The friction coefficient between diamond and some non-ferrous metals is lower than that of other tools. This low friction coefficient results in less deformation during machining, which reduces cutting forces.
③ Extremely sharp cutting edges: Diamond cutting edges can be sharpened to a remarkable degree, with natural single-crystal diamond cutting edges reaching as high as 0.002 to 0.008 μm, enabling ultra-thin cutting and ultra-precision machining.
④ High thermal conductivity: Diamond’s high thermal conductivity and thermal diffusivity allow for easy dissipation of cutting heat, keeping the tool’s cutting surface temperature low.
⑤ Low thermal expansion coefficient: Diamond’s thermal expansion coefficient is several times smaller than that of cemented carbide, minimizing tool dimensional changes caused by cutting heat. This is particularly important for Samshion’s precision and ultra-precision machining, where dimensional accuracy is critical.
Where and How Are Diamond Tools Used?
At Samshion, diamond tools are primarily used for high-speed precision cutting and boring of nonferrous and nonmetallic materials. They are suitable for machining various wear-resistant nonmetals, such as fiberglass powder metallurgy blanks and ceramics; various wear-resistant nonferrous metals, such as various silicon-aluminum alloys; and various nonferrous metal finishing operations.
The disadvantage of diamond tools is their poor thermal stability. When cutting temperatures exceed 700°C to 800°C, they completely lose their hardness. Furthermore, they are unsuitable for cutting ferrous metals because diamond (carbon) readily reacts with iron atoms at high temperatures, converting the carbon atoms into a graphite structure, which can easily damage the tool.
Cubic Boron Nitride (CBN) – Why Is It the Go-To for Steel at Samshion?
Tell you that, cubic boron nitride (CBN), a second superhard material synthesized using a method similar to diamond manufacturing, is second only to diamond in hardness and thermal conductivity. It also exhibits excellent thermal stability and does not oxidize even when heated to 10,000°C in air. CBN exhibits extremely stable chemical properties with respect to ferrous metals and is widely used in the machining of steel products.
What Types of Cubic Boron Nitride Tools Are There?
Samshion’s CNC operators use both Solid PCBN inserts and PCBN composite inserts sintered with cemented carbide. CBN is a substance that does not exist in nature. It can be divided into single crystal and polycrystalline forms, namely single crystal CBN and polycrystalline cubic boron nitride. Bornnitride (PCBN) is an allotrope of boron nitride (BN) with a structure similar to diamond.
Our CNC operators at Samshion utilize PCBN inserts to ensure consistent surface quality and tool life. PCBN (polycrystalline cubic boron nitride) is a polycrystalline material sintered together under high temperature and high pressure using finely divided CBN material with a binder phase (such as TiC, TiN, Al, and Ti). Currently, it is the hardest synthetic tool material second only to diamond. Together with diamond, it is collectively referred to as a superhard tool material. PCBN is primarily used in the manufacture of cutting tools and other tools.
PCBN tools can be divided into solid PCBN inserts and PCBN composite inserts sintered with cemented carbide. PCBN composite inserts are made by sintering a 0.5-1.0 mm thick layer of PCBN onto a carbide with good strength and toughness. They combine excellent toughness with high hardness and wear resistance, addressing the problems of low bending strength and welding difficulties associated with CBN inserts. Samshion engineers optimize insert selection based on the machining task and material hardness.
What Are the Performance and Characteristics of Ceramic Tools?
Although slightly inferior to diamond in hardness, CBN’s hardness is significantly higher than other high-hardness materials. CBN’s outstanding advantage is its much higher thermal stability than diamond, reaching temperatures exceeding 1200°C (diamond’s is 700-800°C). Another outstanding advantage is its high chemical inertness, remaining unreactive with iron even at temperatures between 1200 and 1300°C. The main properties and characteristics of cubic boron nitride are as follows:
① High Hardness and Wear Resistance: CBN’s crystal structure is similar to that of diamond, resulting in similar hardness and strength. PCBN is particularly well-suited for machining high-hardness materials that were previously only grindable, achieving superior workpiece surface quality. Samshion’s CNC operators benefit from these properties when finishing hardened steel parts.
② High Thermal Stability: CBN’s heat resistance reaches 1400-1500°C, almost double that of diamond (700-800°C). PCBN tools can cut high-temperature alloys and hardened steel at speeds three to five times higher than carbide tools.
③ Excellent chemical stability: PCBN does not react chemically with iron-based materials even at temperatures up to 1200-1300°C, and does not wear rapidly like diamond. At this temperature, it maintains the hardness of carbide. PCBN tools are suitable for cutting hardened steel parts and chilled cast iron, and are widely used in high-speed cutting of cast iron.
④ Good thermal conductivity: While CBN’s thermal conductivity cannot match that of diamond, it is second only to diamond among all tool materials and significantly higher than high-speed steel and carbide.
⑤ Low coefficient of friction: A low coefficient of friction reduces cutting forces and temperatures, resulting in improved surface quality. This helps Samshion CNC operators achieve smoother finishes with less tool wear.
What Are the Applications of Cubic Boron Nitride Tools?
Cubic Boron Nitride is suitable for finishing difficult-to-cut materials such as hardened steel, hard cast iron, high-temperature alloys, cemented carbide, and surface-coated materials. Machining accuracy can reach IT5 (IT6 for holes), and surface roughness can be as low as Ra1.25 to 0.20μm.
Cubic Boron Nitride tool materials have poor toughness and bending strength. Therefore, cubic boron nitride turning tools are not suitable for rough machining at low speeds and under high impact loads. They are also not suitable for cutting highly plastic materials (such as aluminum alloys, copper alloys, nickel-based alloys, and highly plastic steels) because cutting these metals can produce severe built-up edge, which deteriorates the machined surface.
Why Are Ceramic Tools Widely Used by Samshion’s CNC Team?
Ceramic tools offer high hardness, excellent wear resistance, heat resistance, and chemical stability. They also resist adhesion to metal. Ceramic cutting tools play a crucial role in CNC machining, becoming a staple in high-speed cutting and machining difficult-to-machine materials. They are widely used in high-speed cutting, dry cutting, hard cutting, and machining of difficult-to-machine materials. Ceramic cutting tools can efficiently machine extremely hard materials that traditional tools simply cannot, effectively replacing grinding with turning. The optimal cutting speed of ceramic cutting tools can be 2 to 10 times higher than that of carbide cutting tools, significantly improving cutting efficiency. The primary raw material used in ceramic cutting tools is the most abundant element in the Earth’s crust. Therefore, the widespread use of ceramic cutting tools is crucial for improving productivity, reducing machining costs, and conserving strategically valuable precious metals. It will also significantly promote advancements in cutting technology.
What Types of Ceramic Tool Materials Exist?
Ceramic tool materials can generally be divided into three categories: alumina-based ceramics, silicon nitride-based ceramics, and composite silicon nitride-alumina-based ceramics. Alumina-based and silicon nitride-based ceramic tool materials are the most widely used. Silicon nitride-based ceramics have superior performance compared to alumina-based ceramics.
What Are the Performance and Characteristics of Ceramic Tools?
① High Hardness and Good Wear Resistance: While not as high as PCD and PCBN, the hardness of ceramic tools is significantly higher than that of carbide and high-speed steel tools, reaching 93-95 HRA. Ceramic tools can process high-hardness materials that are difficult to machine with traditional tools, making them suitable for high-speed cutting and hard cutting.
② High-Temperature Resistance: Ceramic tools can still cut at temperatures exceeding 1200°C. Ceramic tools exhibit excellent high-temperature mechanical properties, and Al2O3 ceramic tools have particularly good oxidation resistance, allowing continuous use even when the cutting edge is red-hot. Therefore, ceramic tools can achieve dry cutting, eliminating the need for cutting fluid.
③ Good Chemical Stability: Ceramic cutting tools are not prone to bonding with metals and are corrosion-resistant and chemically stable, reducing tool wear.
④ Low Friction Coefficient: Ceramic cutting tools have a low affinity for metals and a low friction coefficient, which reduces cutting forces and temperatures.
What Are the Applications of Ceramic Cutting Tools?
Ceramic is one of the tool materials primarily used for high-speed finishing and semi-finishing. Ceramic cutting tools are suitable for cutting various cast irons (gray cast iron, ductile iron, malleable cast iron, chilled cast iron, high-alloy wear-resistant cast iron) and steels (carbon structural steel, alloy structural steel, high-strength steel, high-manganese steel, hardened steel, etc.). They can also be used for cutting copper alloys, graphite, engineering plastics, and composite materials.
Ceramic cutting tools have low flexural strength and poor impact toughness, making them unsuitable for cutting at low speeds and under impact loads.
Why Are Coated Cutting Tool Materials Crucial in CNC Machining?
At Samshion, our engineers and CNC operators rely on coated tools to achieve higher precision and efficiency in production.Ceramic cutting tools are suitable for cutting various cast irons (gray cast iron, ductile iron, malleable cast iron, chilled cast iron, high-alloy wear-resistant cast iron) and steels (carbon structural steel, alloy structural steel, high-strength steel, high-manganese steel, hardened steel, etc.). Coating is one of the key ways to improve tool performance. The emergence of coated tools has brought about significant breakthroughs in cutting performance. Coated tools are made by coating a tough tool body with one or more layers of a wear-resistant, refractory compound. This combines the tool base with the hard coating, significantly enhancing tool performance. Coated tools can improve machining efficiency, increase machining accuracy, extend tool life, and reduce machining costs.
Approximately 80% of the cutting tools used in new CNC machine tools are coated. Coated tools will be the most important tool type in the future of CNC machining.
What Are the Different Types of Coated Tools?
Based on the coating method, coated tools can be divided into chemical vapor deposition (CVD) and physical vapor deposition (PVD) coatings. Coated carbide tools are generally coated using CVD, with a deposition temperature around 1000°C. Coated high-speed steel tools are generally coated using PVD, with a deposition temperature around 500°C. So Samshion engineers choose coating methods depending on the substrate material and machining conditions.
Based on the substrate material, coated tools can be divided into carbide-coated tools, high-speed steel-coated tools, and tools coated on ceramics and superhard materials (diamond and cubic boron nitride).
Based on the properties of the coating material, coated tools can be further divided into two categories: “hard” coated tools and “soft” coated tools. “Hard” coated tools primarily aim for high hardness and wear resistance. Their main advantages are high hardness and good wear resistance. Typical examples are TiC and TiN coatings. “Soft” coated tools aim for a low coefficient of friction. Also known as self-lubricating tools, they have a very low coefficient of friction with the workpiece material, around 0.1, which reduces adhesion, friction, and lowers cutting forces and temperatures.
Recently, nano-coatings have been developed. Nanoelectrolyzed tools. These coated tools can utilize various combinations of coating materials (such as metal/metal, metal/ceramic, ceramic/ceramic, etc.) to meet diverse functional and performance requirements. A properly designed nanocoating imparts excellent friction reduction, anti-wear properties, and self-lubricating properties to the tool material, making it suitable for high-speed dry cutting. Samshion’s CNC operators often work with nano-coated tools to maximize tool life and surface quality.
What Are the Key Characteristics of Coated Tools?
① Excellent Mechanical and Cutting Performance: Coated tools combine the excellent properties of the base material and the coating material, maintaining the substrate’s excellent toughness and high strength while also offering the coating’s high hardness, high wear resistance, and low friction coefficient. Consequently, the cutting speed of coated tools can be more than doubled compared to uncoated tools, allowing for higher feed rates. Coated tool life is also improved.
② High Versatility: Coated tools offer a wide range of versatility, significantly expanding their processing range. One coated tool can replace several uncoated tools. Samshion’s engineers leverage this versatility to streamline machining processes across multiple projects.
③ Coating Thickness: Tool life increases with increasing coating thickness, but once the coating reaches saturation, tool life no longer significantly improves. Too thick a coating can easily cause delamination; too thin a coating can result in poor wear resistance.
④Regrindability: Coated inserts have poor regrindability, complex coating equipment, high process requirements, and long coating times.
⑤ Coating Material: Tools with different coating materials exhibit varying cutting performance. For example, TiC coatings offer advantages at low cutting speeds, while TiN coatings are more suitable at high cutting speeds.
How Are Coated Tools Applied in CNC Machining?
Coated tools hold enormous potential in CNC machining and will be the most important tool type in this field in the future. Coating technology has been applied to end mills, reamers, drills, composite hole-making tools, gear hobs, gear shaping cutters, shaving cutters, form broaches, and various machine-mounted indexable inserts, meeting the needs of high-speed cutting of various materials, including steel and cast iron, heat-resistant alloys, and non-ferrous metals. Samshion’s R&D continues to explore advanced coated tool applications to push machining efficiency and precision to new levels.
Cemented Carbide Tool Materials – Why are they very commonly used in the CNC industry?
Cemented carbide tools, especially indexable carbide tools, are the leading CNC machining tool product. Since the 1980s, the variety of solid and indexable carbide tools or inserts has expanded into various cutting tool applications. Indexable carbide tools have expanded from simple turning tools and face milling cutters to a variety of precision, complex, and forming tools. Samshion’s engineering team frequently utilizes cemented carbide tools for high-precision CNC projects, ensuring both efficiency and surface quality.
How Are Cemented Carbide Tools Classified?
Based on their primary chemical composition, cemented carbide can be divided into tungsten carbide-based cemented carbide and titanium carbide (TiC(N))-based cemented carbide.
Tungsten carbide-based cemented carbide includes three types: tungsten-cobalt (YG), tungsten-cobalt-titanium (YT), and rare carbide-added cemented carbide (YW). Each has its own advantages and disadvantages. Their primary components include tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC), and niobium carbide (NbC). Cobalt is a common metal bonding phase.
Titanium carbonitride-based cemented carbide is a hard alloy with TiC as the primary component (some also contain other carbides or nitrides). Mo and Ni are commonly used as metal binders.
ISO (International Organization for Standardization) classifies cutting carbide into three categories:
K category, including K10 to K40, is equivalent to my country’s YG category (primarily composed of WC and Co).
P category, including P01 to P50, is equivalent to my country’s YT category (primarily composed of WC, TiC, and Co).
M category, including M10 to M40, is equivalent to my country’s YW category (primarily composed of WC-TiC-TaC(NbC)-Co). The various grades are designated with numbers ranging from 01 to 50, representing a range of alloys from high hardness to maximum toughness. Samshion’s R&D team evaluates these grades carefully to select optimal tools for different CNC projects.
What Performance Features Make Cemented Carbide Tools Reliable?
① High Hardness: Cemented carbide tools are manufactured through powder metallurgy using a combination of carbides (called the hard phase) with very high hardness and melting points and a metal binder (called the bonding phase). Their hardness reaches 89-93 HRA, significantly higher than that of high-speed steel. Even at 5400°C, their hardness can still reach 82-87 HRA, comparable to the room-temperature hardness of high-speed steel (83-86 HRA). The hardness of cemented carbide varies with the nature, quantity, and particle size of the carbides and the content of the metal bonding phase. Generally, it decreases with increasing metal bonding phase content. At the same bonding phase content, YT alloys have higher hardness than YG alloys, and alloys with TaC (NbC) additions exhibit higher high-temperature hardness. ② Flexural Strength and Toughness: The flexural strength of commonly used cemented carbides ranges from 900 to 1500 MPa. A higher metal bonding phase content increases the flexural strength. When the binder content is the same, YG (WC-Co) alloys have higher strength than YT (WC-TiC-Co) alloys, and the strength decreases with increasing TiC content. Cemented carbide is a brittle material, with an impact toughness at room temperature only 1/30 to 1/8 that of high-speed steel. Samshion CNC operators account for these factors to minimize tool breakage.
How Are Cemented Carbide Tools Applied in Real CNC Operations?
YG alloys are primarily used for machining cast iron, nonferrous metals, and non-metallic materials. Fine-grained carbides (such as YG3X and YG6X) have higher hardness and wear resistance than medium-grained carbides at the same cobalt content. They are suitable for machining certain hard cast irons, austenitic stainless steels, heat-resistant alloys, titanium alloys, hard bronzes, and wear-resistant insulating materials.
YT carbide’s outstanding advantages include high hardness, excellent heat resistance, higher hardness and compressive strength at high temperatures than YG, and better oxidation resistance. Therefore, when high heat resistance and wear resistance are required for tools, grades with higher TiC content should be selected. YT alloys are suitable for machining plastic materials such as steel, but are not suitable for machining titanium alloys or silicon-aluminum alloys.
YW alloys combine the properties of YG and YT alloys, offering excellent overall performance. They can be used for machining steel, cast iron, and nonferrous metals. By appropriately increasing the cobalt content, these alloys can achieve very high strength, making them suitable for roughing and interrupted cutting of various difficult-to-machine materials.
Why Are High-Speed Steel (HSS) Tools Essential in Modern CNC Machining?
Samshion’s CNC operators frequently rely on HSS tools for precision machining of complex parts. High-Speed Steel (HSS) is a high-alloy tool steel containing a high concentration of alloying elements such as W, Mo, Cr, and V. HSS tools offer excellent overall performance in terms of strength, toughness, and processability. They continue to dominate the market for complex tools, particularly those with complex cutting edges, such as holemaking tools, milling cutters, threading cutters, broaches, and gear cutting tools. High-Speed Steel tools are easy to sharpen to a sharp cutting edge.
Depending on their intended use, high-speed steel can be divided into general-purpose and high-performance HSS.
What Defines General-Purpose High-Speed Steel Tools?
General-Purpose High-Speed Steel. Generally, they can be divided into two categories: tungsten steel and tungsten-molybdenum steel. This type of high-speed steel contains 0.7% to 0.9% tungsten. Depending on the tungsten content, it can be classified as tungsten steel with 12% or 18% tungsten, tungsten-molybdenum steel with 6% or 8% tungsten, and molybdenum steel with 2% or no tungsten. General-purpose high-speed steels offer a certain hardness (63-66 HRC), wear resistance, high strength and toughness, good plasticity, and machinability, making them widely used in the manufacture of various complex cutting tools.
① Tungsten steel: The typical grade of general-purpose high-speed steel, W18Cr4V (abbreviated as W18), offers excellent overall performance, with a high-temperature hardness of 48.5 HRC at 600°C, making it suitable for the manufacture of various complex cutting tools. It has advantages such as good grindability and low decarburization sensitivity. However, due to its high carbide content, uneven distribution, and large particles, it suffers from low strength and toughness.
② Tungsten-molybdenum steel: This refers to a high-speed steel obtained by replacing a portion of the tungsten in tungsten steel with molybdenum. A typical grade of tungsten-molybdenum steel is W6Mo5Cr4V2 (abbreviated as M2). M2’s carbide particles are fine and uniform, and its strength, toughness, and high-temperature ductility are superior to W18Cr4V. Another tungsten-molybdenum steel, W9Mo3Cr4V (abbreviated as W9), offers slightly higher thermal stability than M2 steel, better bending strength and toughness than W6M05Cr4V2, and excellent machinability.
How Do High-Performance HSS Tools Improve Cutting Capabilities?
High-performance high-speed steel refers to a new type of steel that increases the carbon and vanadium content of general-purpose high-speed steel, as well as alloying elements such as Co and Al, to enhance its heat resistance and wear resistance. It mainly falls into the following categories:
① High-carbon high-speed steel. High-carbon high-speed steel (such as 95W18Cr4V) has high hardness at both room and high temperatures. It is suitable for manufacturing tools such as drills, reamers, taps, and milling cutters for machining ordinary steel and cast iron, tools requiring high wear resistance, or tools for machining harder materials. It should not be subjected to heavy impact.
② High-vanadium high-speed steel. Typical grades include W12Cr4V4Mo (EV4). The vanadium content is increased to 3-5%. It has excellent wear resistance and is suitable for cutting materials that are extremely abrasive to the tool, such as fibers, hard rubber, and plastics. It can also be used for machining stainless steel, high-strength steel, and high-temperature alloys.
③ Cobalt high-speed steel. This is a cobalt-containing superhard high-speed steel. Typical grades include W2Mo9Cr4VCo8 (M42). It has a high hardness of 69-70 HRC and is suitable for machining difficult-to-machine materials such as high-strength heat-resistant steel, high-temperature alloys, and titanium alloys. M42 has excellent grindability and is suitable for making precision and complex tools, but is not suitable for use under impact cutting conditions.
④ Aluminum High-Speed Steel. This is an aluminum-containing, super-hard high-speed steel. Typical grades include W6Mo5Cr4V2Al (abbreviated as 501). Its high-temperature hardness reaches 54HRC at 6000°C, and its cutting performance is equivalent to that of M42. It is suitable for manufacturing milling cutters, drills, reamers, gear cutters, broaches, and other materials. It is used for machining alloy steel, stainless steel, high-strength steel, and high-temperature alloys.
⑤ Nitrogen Super-Hard High-Speed Steel. Typical grades include W12M03Cr4V3N (abbreviated as (V3N). This is a nitrogen-containing, super-hard high-speed steel with hardness, strength, and toughness comparable to M42. It can be used as an alternative to cobalt-containing high-speed steel for low-speed cutting of difficult-to-machine materials and low-speed, high-precision machining.
What Are the Advantages of Melted vs. Powder Metallurgy HSS?
Depending on the manufacturing process, high-speed steel can be divided into melting high-speed steel and powder metallurgy high-speed steel. Samshion’s engineering team often recommends PMHSS for demanding prototype and small-batch projects requiring both toughness and long service life.
① Melted High-Speed Steel: Both ordinary and high-performance high-speed steels are manufactured using the melting method. These steels are made into cutting tools through processes such as smelting, ingot casting, and plating and rolling. A serious problem with melted high-speed steel is carbide segregation. Hard and brittle carbides are unevenly distributed throughout the steel, and the grains are coarse (up to tens of microns in size), adversely affecting the wear resistance, toughness, and cutting performance of the high-speed steel cutting tools. ② Powder Metallurgy High-Speed Steel (PMHSS): Powder Metallurgy High-Speed Steel (PMHSS) is produced by atomizing molten steel smelted in a high-frequency induction furnace using high-pressure argon or pure nitrogen, followed by rapid cooling to produce a fine, uniform crystalline structure (high-speed steel powder). The resulting powder is then pressed into a cutting tool blank under high temperature and high pressure, or formed into a billet and then forged and rolled into the cutting tool shape. Compared to melt-made high-speed steel, PMHSS offers advantages: fine and uniform carbide grains, significantly improved strength, toughness, and wear resistance compared to melted high-speed steel. In the field of complex CNC tooling, PM HSS tools will continue to develop and occupy a significant position. Typical grades, such as F15, FR71, GF1, GF2, GF3, PT1, and PVN, can be used to manufacture large-scale tools that withstand heavy loads and high impact, as well as precision tools.
How Does Samshion Ensure the Right CNC Tool Material for Each Job?
Currently, widely used CNC tool materials include diamond tools, cubic boron nitride tools, ceramic tools, coated tools, carbide tools, and high-speed steel tools. There are many grades of tool materials, and their performance varies greatly. The following table lists the main performance indicators of various tool materials.
Main Performance Indicators of Various Tool Materials
Tool materials for CNC machining must be selected based on the workpiece being machined and the nature of the process. The tool material should be appropriately matched to the machining object. Matching the cutting tool material with the machining object primarily refers to matching their mechanical, physical, and chemical properties to maximize tool life and cutting productivity.
How Do Mechanical Properties Influence Tool Selection?
Matching the mechanical properties of cutting tools with the workpiece primarily refers to matching mechanical properties such as strength, toughness, and hardness between the tool and the workpiece. Tool materials with different mechanical properties are suitable for machining different workpiece materials.
① The order of tool material hardness is: diamond tools > cubic boron nitride tools > ceramic tools > cemented carbide > high-speed steel.
② The order of tool material bending strength is: high-speed steel > cemented carbide > ceramic tools > diamond and cubic boron nitride tools.
③ The order of tool material toughness is: high-speed steel > cemented carbide > cubic boron nitride, diamond, and ceramic tools.
High-hardness workpiece materials require tools of even higher hardness. The tool material’s hardness must be higher than the workpiece’s hardness, generally requiring at least 60 HRC. The higher the hardness of the tool material, the better its wear resistance. For example, increasing the cobalt content in cemented carbide increases its strength and toughness while decreasing its hardness, making it suitable for rough machining. Decreasing the cobalt content increases its hardness and wear resistance, making it suitable for fine machining.
Tools with excellent high-temperature mechanical properties are particularly well-suited for high-speed cutting. The excellent high-temperature performance of ceramic tools enables high cutting speeds, with permissible cutting speeds 2 to 10 times higher than those of cemented carbide.
How Are Physical Properties Matched to Workpieces?
Tools with different physical properties, such as high-speed steel tools with high thermal conductivity and low melting points, ceramic tools with high melting points and low thermal expansion, and diamond tools with high thermal conductivity and low thermal expansion, are suitable for machining different workpiece materials. When machining workpieces with poor thermal conductivity, tool materials with better thermal conductivity should be used to quickly dissipate cutting heat and reduce cutting temperatures. Diamond, due to its high thermal conductivity and thermal diffusivity, dissipates cutting heat easily without significant thermal deformation. This is particularly important for precision machining tools requiring high dimensional accuracy.
① Heat resistance of various tool materials: 700-8000°C for diamond tools, 13000-15000°C for PCBN tools, 1100-12000°C for ceramic tools, 900-11000°C for TiC(N)-based cemented carbide, 800-9000°C for WC-based ultrafine-grained cemented carbide, and 600-7000°C for HSS.
② The order of thermal conductivity of various tool materials is: PCD > PCBN > WC-based cemented carbide > TiC(N)-based cemented carbide > HSS > Si3N4-based ceramics > Al2O3-based ceramics.
③ The order of thermal expansion coefficients of various tool materials is: HSS > WC-based cemented carbide > TiC(N) > Al2O3-based ceramics > PCBN > Si3N4-based ceramics > PCD.
④ The order of thermal shock resistance of various tool materials is: HSS > WC-based cemented carbide > Si3N4-based ceramics > PCBN > PCD > TiC(N)-based cemented carbide > A1203-based ceramics.
How Are Chemical Properties Considered in Tool Selection?
The chemical matching of cutting tool materials and workpieces primarily refers to the matching of chemical parameters such as chemical affinity, chemical reaction, diffusion, and solubility between the tool and workpiece materials. Tools made of different materials are suitable for machining different workpiece materials.
① The order of anti-adhesion temperatures of various tool materials (with steel) is: PCBN > ceramics > cemented carbide > HSS.
② The order of anti-oxidation temperatures of various tool materials is: ceramics > PCBN > cemented carbide > diamond > HSS.
③ The order of diffusion strength of various tool materials (with steel) is: diamond > Si3N4-based ceramics > PCBN > A1203-based ceramics. The diffusion strength order (for titanium) is: A1203-based ceramic > PCBN > SiC > Si3N4 > diamond.
Which CNC Tool Materials Are Best for Different Workpieces?
Generally speaking, PCBN, ceramic tools, coated carbide, and TiCN-based carbide tools are suitable for CNC machining of ferrous metals such as steel; while PCD tools are suitable for machining non-ferrous metals such as Al, Mg, and Cu, their alloys, and non-metallic materials.
Samshion’s CNC team selects tool materials based on project requirements, ensuring optimal performance for each workpiece type. The following table lists suitable tool materials for common workpiece materials.
