With the development of science, gears have gradually changed from metal gears to plastic gears. Because plastic gears have better lubricity and wear resistance. It can reduce noise, cost and friction.

　　Common plastic gear materials include: PVC, POM, PTFE, PA, nylon, peek, etc.

　　Automobile gear

　　There are many grades of steel for gears of medium and heavy trucks in China, mainly to meet the requirements of introducing foreign advanced automobile technology at that time. In the 1950s, China introduced the production technology of the Soviet Union's medium-sized truck (i.e. the original model of "liberation" brand) from the former Soviet Union's rikhachov automobile factory. At the same time, it also introduced 20CrMnTi steel for automobile gears produced by the former Soviet Union.

　　After the reform and opening up, with the rapid development of China's economic construction, in order to meet the needs of the rapid development of China's transportation, since the 1980s, China has systematically introduced all kinds of advanced models from industrial developed countries, and all kinds of foreign advanced medium and heavy trucks have also been introduced. At the same time, China's large automobile factories cooperate with foreign famous automobile companies to introduce foreign advanced automobile production technology, including automobile gear production technology. At the same time, China's iron and steel smelting technology is also constantly improving. The use of advanced smelting technologies such as ladle secondary smelting, composition fine adjustment and continuous casting and rolling enables the steel plant to produce gear steel with high purity and narrow hardenability, so as to realize the localization of imported automobile gear steel, and raise the production level of gear steel to a new level in China. Nickel containing high hardenability steel for domestic heavy truck gears, which is suitable for China's national conditions, has also been applied and achieved good results. The heat treatment technology of automobile gears has also developed from well gas carburizing in the 1950s and 1960s to the current common use of computer-controlled continuous gas carburizing automatic line, box multi-purpose furnace and automatic production line (including low-pressure (vacuum) carburizing technology), gear carburizing preoxidation technology, gear quenching control cooling technology (due to the use of special quenching oil and quenching cooling technology) Isothermal Normalizing Technology of gear forging blank, etc. The adoption of these technologies not only effectively controls the carburizing and quenching distortion of gears, improves the machining accuracy and prolongs the service life of gears, but also meets the needs of mass production of modern heat treatment of gears.