According to the data of Baidu Encyclopedia, the national standard stipulates the accuracy grade of 13 for gear pairs. Among the accuracy grades of 13, the processing technology level and measuring means of 0, 1 2 accuracy are still difficult to reach and need to be developed. Grade 3-5 is high precision, grade 6-8 is medium precision, and grade 9- 12 is low precision. Machining accuracy is usually required to be in micron level, that is, the accuracy should be below 0.001mm.

Gear accuracy includes four indexes: motion accuracy, smoothness accuracy, contact accuracy and backlash accuracy. The selection of gear accuracy grade should be determined according to the purpose, service conditions, transmission power, peripheral speed, performance index or other technical requirements of transmission.