After hardening or strengthening of gear surface by heat treatment, there are often black oxide skin or other defects, such as excessive surface roughness or surface decarburization. The final machining of gears is often to ensure the surface quality of fine machining, such as grinding, honing and polishing. Recently, Japan and Germany have developed many relatively new polishing processes and applied for many patent technologies. Recently, China has also developed pulse electrochemical mechanical polishing technology for gear polishing to improve the surface finish [23]. The final machining of gears has a great influence on the surface integrity of gears, which should be paid attention to and studied, which is not very concerned in China. Therefore, it is often delivered to customers after the surface hardening or strengthening of gears, without further fine machining to improve the surface integrity and thus better extend the service life of gears.

Generally speaking, most of the gear processing in China is still in the forming and manufacturing stage, lacking of the gear surface integrity manufacturing technology system. Even though the conventional shot peening technology has many problems in the actual engineering, the application effect is not ideal, let alone a complete surface integrity quality inspection technology platform, This results in that the key basic transmission components of gears manufactured in China are in the low middle level, and it is difficult to manufacture high-end gear transmission components. In this technical background, China’s high-end gear applications have to rely on imports, such as domestic high-speed iron gear imported from Germany, helicopter engine transmission gear imported from Italy, etc., which seriously limits the development of China’s national economy and national defense strength.