Short Answer:
Tool materials used in machining are special materials that can cut or shape other materials effectively. These tool materials need to be strong, hard, and resistant to heat and wear. Common tool materials include high-speed steel, carbide, ceramic, diamond, and cubic boron nitride (CBN).
Each tool material has specific properties suited for particular machining tasks. High-speed steel tools are commonly used for general-purpose machining. Carbide tools are strong and durable for fast and heavy cutting. Ceramic, diamond, and CBN tools are used for high-speed operations, machining hard materials, and achieving very fine finishes.
Detailed Explanation:
Types of Tool Materials
Selecting the right tool material is very important in machining because it directly affects the efficiency, precision, and quality of the machining operation. Below are the main types of tool materials commonly used:
- High-Speed Steel (HSS)
High-speed steel is a popular and affordable tool material widely used in workshops. It contains elements like tungsten, chromium, vanadium, and molybdenum. These elements improve hardness, toughness, and resistance to heat and wear. HSS can withstand high temperatures without losing hardness. It is easy to shape and sharpen, making it suitable for general-purpose machining, such as drilling, milling, threading, and turning. HSS tools are usually used for machining softer materials like aluminum, brass, mild steel, and plastics. - Carbide Tool Material
Carbide tools, often called cemented carbide tools, are made by combining tungsten carbide particles with a metallic binder such as cobalt. Carbide tools are extremely hard, strong, and resistant to heat and wear. These properties allow carbide tools to operate at higher cutting speeds and endure heavier loads compared to HSS. Carbide tools maintain sharp edges for a long time, making them ideal for high-speed machining and heavy-duty cutting of hard materials like stainless steel, cast iron, and alloy steels. Carbide tools often come as inserts attached to steel holders, reducing the cost of replacing entire tools. - Ceramic Tool Material
Ceramic tools are made from aluminum oxide or silicon nitride. They are even harder and more heat-resistant than carbide tools. Ceramic tools maintain their hardness and strength at very high temperatures, enabling them to operate at extremely high cutting speeds. They are particularly effective for finishing operations on hardened steels, cast iron, and heat-resistant alloys. However, ceramic tools are brittle and less tough, making them sensitive to sudden impacts or vibrations. They are usually not suitable for rough machining or interrupted cutting conditions. - Diamond Tool Material
Diamond is the hardest known material, and diamond cutting tools are used for extremely precise and high-quality machining. Diamond tools are mainly available in two types: natural diamond and synthetic (polycrystalline) diamond. Natural diamond tools provide exceptional surface finishes and precise machining but are very expensive. Synthetic diamond tools offer similar performance at a lower cost. Diamond tools are best suited for machining non-ferrous materials like aluminum, copper, brass, ceramics, glass, and plastics. Diamond is generally not used to machine ferrous metals due to chemical reactions at high temperatures that can damage the tool. - Cubic Boron Nitride (CBN)
CBN is the second hardest tool material after diamond. CBN tools are excellent for machining extremely hard ferrous materials like hardened steels, cast iron, and alloys that diamond tools cannot efficiently machine. CBN tools withstand very high temperatures without losing hardness or sharpness. They are primarily used for precision finishing operations, hard turning, and grinding applications requiring high accuracy and fine surface finishes.
Conclusion
Selecting appropriate tool materials ensures efficient and high-quality machining. High-speed steel is suitable for general tasks, while carbide is excellent for high-speed and heavy-duty machining. Ceramic tools are used for finishing and precision cutting at high speeds. Diamond and CBN are reserved for the hardest and most precise machining tasks. Choosing the correct tool material based on application requirements can significantly improve productivity, quality, and cost-effectiveness.