Machine standard rules on the precision grade 12, according to the accuracy of the sequence from high to low with a Numbers 1, 2, 3,... More than 12, according to the commonly used for 5 ~ 9 accuracy. In addition, according to the movement of the transmission accuracy, stability and load distribution uniformity of different requirements, each precision grades of the tolerance, in turn, can be divided into three groups, the first Ⅰ machine tolerance group, the first Ⅱ tolerance group and the first Ⅲ tolerance group.

Gear precision level should be based on the purposes of transmission, use condition, the transmission efficiency and circumferential velocity and other economic and technical index.

Level 5 gear for precision level.

Processing method: periodic error is very small in high precision gear machine tool of selecting such assignment. Tooth surface precision grinding, eventually go after large gear with precision rolling gear hobbing, in grinding or shaving. Tooth surface roughness is 0.4 to 0.4.

Using range: precision of dividing mechanism of gear; Used in high speed, and the operation stability and have higher requirements of gear noise; High speed turbine gear etc.

7 level gear for high precision level.

Processing method: of selecting such assignment on the machine with high precision gear. Not quenching of tooth surface with high precision cutting system; Quenching of gears need finishing (grinding teeth, shaving, grinding, etc.). Tooth surface roughness is 1.6.

Use scope: used in high speed, small load or reverse gear; Machine tool feed gear, need movement with gear; Medium speed reduction gear; The plane gear; Herringbone tooth gear at a moderate speed, etc.

Resources: mechanical design manual