How to divide the grade of gear accuracy of gear reducer

The gear accuracy of gear reducer has 12 grades, which are represented by the numbers 1, 2, 3,... 12 in order of accuracy from high to low. Most commonly used are Grade 5 ~ 9 accuracy. In addition, according to the different requirements for motion accuracy, transmission stability and load distribution uniformity, the tolerances of each accuracy level are divided into three groups, I tolerance group, II tolerance group and III tolerance group.
The accuracy grade of gear of gear reducer shall be determined according to the purpose of transmission, service conditions, transmission efficiency, circumferential speed and other economic and technical indexes.
Grade 5 gears are precision grade.
Machining method: model machining on precision gear machine tool with very small periodic error. The tooth surface adopts precision grinding, and large gears are ground or shaved after Hobbing with precision hobbing. The tooth surface roughness reaches 0.4-0.8.
Scope of application: precision gear for indexing mechanism; Used for gears with high speed and high requirements for running stability and noise; Gears for high-speed steam turbines, etc.
Level 7 gear is a relatively high precision level.
Machining method: model machining on high-precision gear machine tool. The non quenched tooth surface is cut with high-precision tools; Hardened gears need finishing (grinding, shaving, grinding, etc.). The tooth surface roughness reaches 1.6.
Scope of application: for gears with high speed, small load or reverse rotation; The feed gear of the machine tool needs to move a matched gear; Medium speed reduction gear; Aircraft gear; Medium speed gear with herringbone teeth, etc.