There are many cutting scenarios under different conditions, and in such cases cutting tools require some unique properties. To achieve this performance, cutting tools are made from different tool materials, and the material selected for a specific application depends on the work material, type of machining process, quantity, and quality of production. According to the materials used, tool materials can be categorized into: 1. Carbon tool steel；2. High-speed steel (HSS)；3. Cemented carbide；4. Ceramic tools；5. Cubic boron nitride (CBN)；6. Diamond tools
Carbon Tool Steel
Carbon tool steel is an inexpensive metal cutting tool material for low-speed machining operations. These ordinary carbon steels contain 0.6-1.5% carbon and very small amounts (<0.5%) of manganese and silicon. Other metals like chromium and vanadium may be added to influence hardness and grain size. High-carbon steels are wear-resistant and can hold a sharp cutting edge. Carbon tool steel has good cutting ability but loses hardness rapidly at around 250°C temperature. Therefore, it is not suitable for high-temperature applications and may be replaceable in current machining operations. Carbon steels are used for taps, milling cutters, turning, and forming tools for soft materials like brass, and aluminum alloys. Temperature – 450°C Hardness – Up to HRC65
High-Speed Steel (HSS)
HSS is a high-carbon steel containing large proportions of alloying elements like tungsten, molybdenum, and chromium to enhance hardenability, toughness, and wear resistance. It provides higher metal removal rates. It loses hardness at around 650°C moderate temperature. Coolant should be used to extend the tool life of HSS. It can be resharpened through grinding for multiple uses. Surface treatments are applied on HSS to improve performance: Polishing – Reduces friction Nitriding – Increases wear resistance Chroming – Reduces friction Oxidizing – Reduces friction HSS material can be used to produce drills, milling cutters, reamers, etc. Cutting speed range: Vc=30-50m/min Temperature – 650°C Hardness – Up to HRC67
Cemented carbide tools are produced using powder metallurgy techniques. It consists of tungsten, tantalum, and titanium carbide with cobalt acting as a binder (nickel or molybdenum as a binder is called metal-ceramic). Cemented carbide tools are extremely hard; they can withstand very high-speed cutting operations. Cemented carbide tools retain their hardness up to 1000°C temperature. High-cobalt grade for roughing and low-cobalt grade for finishing. Cutting speed range Vc=60-200m/min Temperature – 1000°C Hardness – Up to HRC90
The most common ceramic materials are aluminum oxide and silicon nitride. Ceramic powders are pressed and sintered into the required tool holder shape. Ceramic tools are chemically inert and corrosion-resistant. They have high compressive strength and remain stable up to 1800°C temperature, 10 times faster than HSS. Friction between the tool surface and chips is very low. Low thermal conductivity, usually no coolant is required. Ceramic tools can provide a very good surface finish. Cutting speed Vc=300-600m/min Temperature – 1200°C Hardness – Up to HRC93
Cubic Boron Nitride (CBN)
It is the second hardest material after diamond. They are commonly used in manual equipment and have high wear resistance. Can be used for grinding wheels, sharp edges are not recommended. Cutting speed Vc=600-800m/min Hardness – Above HRC95
It is the hardest known material and also the most expensive. It has high thermal conductivity and melting point. Diamond possesses excellent wear resistance, low friction coefficient, and low thermal expansion. It can machine very hard materials like carbides, nitrides, glass, etc.Diamond tooling provides a good surface finish and dimensional accuracy.
What are the main types of tool materials used for cutting tools?
The main types are high-speed steel (HSS), cemented carbide, ceramics, and diamond. Cemented carbide is most commonly used due to its good combination of properties.
What are the advantages of cemented carbide tools?
Cemented carbide tools have high hardness, heat, and wear resistance. They allow higher speeds and feeds than HSS and maintain their geometry longer.
When would you use ceramic tools?
Ceramic tools are suitable for hard, tough materials and very high-speed machining due to their hardness and heat resistance. But they are more brittle than carbide.
What is the advantage of diamond tools?
Diamond tools are extremely hard and can machine very hard materials like carbides, ceramics, glass, and other super-hard materials that other tools cannot cut.
How does coating technology improve tool performance?
Coatings add properties like reducing friction and heat and increasing hardness and wear resistance. This allows higher speeds and feeds for better productivity and surface finish. Common coatings are titanium nitride and aluminum titania.
What factors determine the best tool material for a particular application?
Factors include workpiece material, operation type, cutting parameters, tool life needs, productivity targets, machining accuracy demands, and cost. An optimal material balances all these technical and economic considerations.
In addition, the material of the insert and tool holder block are also important selection factors. The right selection can improve the cost-effectiveness and cutting efficiency of the tool. At the same time, the workpiece material and machining parameters should be matched properly.