Commonly used steels for gear manufacturing include quenched and tempered steel, quenched steel, carburized and quenched steel and nitrided steel. The strength of cast steel is slightly lower than that of forged steel, and it is often used for gears with larger size; The mechanical properties of gray cast iron are poor, which can be used in open gear transmission with light load; Spheroidal graphite cast iron can partly replace steel to make gears; Plastic gears are mostly used in places where light load and low noise are required. The gears matched with plastic gears are generally steel gears with good thermal conductivity.

In the future, gear is developing towards heavy load, high speed, high precision and high efficiency, and strives for small size, light weight, long service life and economic reliability.

The development of gear theory and manufacturing technology will further study the mechanism of gear tooth damage, which is the basis for establishing a reliable strength calculation method, and is the theoretical basis for improving the bearing capacity and prolonging the life of gears; Develop new tooth profiles represented by circular arc tooth profiles; Research new gear materials and new technology of gear manufacturing; Study the elastic deformation, manufacturing and installation errors and temperature field distribution of the gear, and carry out gear tooth modification to improve the stability of gear operation, and increase the contact area of gear teeth when fully loaded, so as to improve the bearing capacity of the gear.

Friction, lubrication theory and lubrication technology are the basic work in gear research. Studying elastohydrodynamic lubrication theory, promoting the use of synthetic lubricating oil and properly adding extreme pressure additives to the oil can not only improve the bearing capacity of the tooth surface, but also improve the transmission efficiency.