A tool is a tool used for machining in machining, and is also called a cutting tool. Most of the knives are machine-based, but they are hand-friendly. Since the tools used in machining are basically used for cutting metal materials, the term "tool" is generally understood as a metal cutting tool. Cutting tools for wood are called woodworking tools. There is also a special type of tool used for geological exploration, well drilling, and mine drilling, called mine tools.

       The development of the tool occupies an important position in the history of human progress. As early as the 28th to the 20th century in China, brass cones, copper drills, knives, and other brass knives have emerged in China. In the late Warring States period (3rd century BC), copper knives were made due to the possession of carburizing technology. Bits and saws at the time were similar to modern flat drills and saws. Tool Cutters However, the rapid development of tools came in the late 18th century with the development of machines such as steam engines. In 1783, René of France first produced a milling cutter. In 1792, Modsley of the United Kingdom made taps and dies. The earliest documented invention of the twist drill was in 1822, but it was not produced as a commodity until 1864.

        The tool at that time was made of high-carbon tool steel and the allowable cutting speed was about 5 m/min. In 1868, Muchert made a tool alloy steel containing tungsten. In 1898, Taylor and the United States. White invented high speed tool steel. In 1923 Schreiter of Germany invented cemented carbide. When alloy tool steels are used, the cutting speed of the tool is increased to about 8 m/min. When high-speed steel is used, it is increased by more than two times. When using carbide, it is more than twice that of high-speed steel. The workpiece surface quality and dimensional accuracy are also greatly improved.

       Due to the high price of high-speed steel and hard alloys, the tool has a welded and mechanically clamped structure. From 1949 to 1950, the United States began to use indexable inserts on lathes and soon to be applied to milling cutters and other tools. In 1938, Germany's Degussa obtained patents on ceramic tools. In 1972, General Electric of the United States produced polycrystalline synthetic diamond and polycrystalline cubic boron nitride inserts. These non-metallic tool materials allow the tool to cut at higher speeds.

        In 1969, the Sandvik Steel Company of Sweden patented a chemical vapor deposition process for the production of titanium carbide coated carbide inserts. In 1972, Bangsa and Rakoland of the United States developed a physical vapor deposition method to coat carbide or HSS cutters with a hard layer of titanium carbide or titanium nitride. The surface coating method combines the high strength and toughness of the base material with the high hardness and wear resistance of the surface layer, so that the composite material has better cutting performance.