The gear precision of the gear reducer has 12 levels, which are represented by numbers 1, 2, 3, ... 12, from high to low level of precision.The most commonly used is 5~9 level precision.In addition, according to the different requirements of motion precision, transmission stability and load distribution uniformity, the tolerances of each precision level are divided into three groups, I tolerance group, II tolerance group and III tolerance group. The accuracy grade of the gear reducer should be determined according to the purpose of transmission, service conditions, transmission efficiency, peripheral speed and other economic and technical indicators. Grade 5 gears are precision grades. Machining method: model machining on precision gear machine tools with very small periodic errors.The surface of the teeth is precision ground, and the large gears are ground or rolled after suspension for precise rolling.The tooth surface roughness reaches 0.4-0.8. Applications: precision gears for indexing mechanisms; gears with high speed and high requirements for running stability and noise; gears such as high-speed steam turbines, etc. Grade 7 gears are a relatively high level of precision. Processing method: model processing on high-precision gear machine tools.Non-hardened tooth surfaces are cut with high-precision tools; hardened gears require finishing (grinding, shaving, grinding, etc.).The tooth surface roughness reaches 1.6. Applications: gears for high speed, load or reverse rotation; feed gears for machine tools need to move matching gears; medium reduction gears; aircraft gears; medium speed gears with herringbone teeth, etc.
