Tools can be divided into five categories according to the form of the workpiece surface. Tools for processing various external surfaces, including turning tools, planers, milling cutters, external surface broaches and files, etc.; hole processing tools, including drills, reamers, boring cutters, reamers and internal surface broaches, etc.; thread processing Tools, including taps, dies, automatic opening and closing thread cutting heads, thread turning tools and thread milling cutters, etc.; gear processing tools, including hobs, gear shapers, gear shaving cutters, bevel gear processing tools, etc.; cutting tools, including inserts Tooth circular saw blades, band saws, bow saws, cut-off turning tools and saw blade milling cutters, etc. In addition, there are combined tools.

According to the cutting motion mode and the corresponding blade shape, cutting tools can be divided into three categories. General tools, such as turning tools, planing cutters, milling cutters (excluding formed turning tools, formed planing cutters and forming milling cutters), boring cutters, drills, reamers, reamers and saws, etc.; forming tools, the cutting edges of such tools It has the same or nearly the same shape as the cross-section of the workpiece to be processed, such as forming turning tools, forming planers, forming milling cutters, broaches, conical reamers and various thread processing tools, etc.; generative tools are used to process gears by the generative method Tooth surface or similar workpieces, such as hobs, gear shapers, gear shaving cutters, bevel gear planers, and bevel gear milling cutters.

Tool materials are roughly divided into the following categories: high-speed steel, cemented carbide, cermet, ceramic, polycrystalline cubic boron nitride and polycrystalline diamond.

I mainly mention ceramics. Ceramics have been used for cutting tools earlier than cemented carbides, but due to their brittleness, their development is slow. But since the 1970s, there has been relatively rapid development. There are two main series of ceramic tool materials, namely alumina series and silicon nitride series. As a cutting tool, ceramics have the advantages of low cost, high hardness, and good high temperature resistance, and have good prospects.