Before the industrial revolution, machines were mostly made of wood and made by carpenters. Metals (mainly copper and iron) are only used to make small parts of instruments, locks, clocks, pumps and wood structures. Metal processing mainly depends on the meticulous work of mechanics to achieve the required accuracy. With the popularization of steam engine power plant and the development of large-scale machinery such as mines, metallurgy, ships and locomotives, more and more metal parts need to be formed and cut, and the required precision is getting higher and higher. The applied metal materials have developed from copper and iron to steel. Mechanical processing, including casting, forging, sheet metal processing, welding, heat treatment and other technologies and equipment, as well as cutting technology and machine tools, tools, measuring tools and so on. The rapid development has ensured the supply of machinery and equipment needed for the development and production of various industries. jet engine

With the development of social economy, the demand for mechanical products has soared. The increase of production batch and the progress of precision machining technology have promoted the formation of a large number of production methods (interchangeability of parts, professional division of labor, assembly line and assembly line, etc.). ). Simple interchangeable parts and professional division of labor have appeared in ancient times. In mechanical engineering, interchangeability is first embodied in the bolts and nuts produced by H. Mozley 1797 with the thread lathe he created. At the same time, American engineer E. Whitney produced muskets with interchangeable production methods, which showed the feasibility and superiority of interchangeability. This production method has gradually spread in the United States, forming the so-called "American production method." At the beginning of the 20th century, H. Ford created an assembly line in the automobile manufacturing industry. A large number of production technologies and scientific management methods founded by F.W. Taylor at the end of 19 have made the production efficiency of mass-produced mechanical products such as automobiles reach unimaginable heights in the past. In the middle and late 20th century, the main features of machining are: ① continuously improving the machining speed and accuracy of machine tools and reducing the dependence on manual skills; (2) Developing less cutting technology; ③ Improve the mechanization and automation of molding, cutting and assembly. Automation has developed from the automation of mechanical control to the automation of electrical control and the complete automation of computer program control, until unmanned workshops and factories; (4) Using CNC machine tools, machining centers and group technology to develop flexible machining systems, so as to improve the production efficiency of small and medium-sized batch and multi-variety production to the level of mass production; ⑤ Research and improve the forming and cutting technology of new metal and nonmetal materials which are difficult to machine.