Products are used in micro-motors, electronic products, auto parts, household appliances, office supplies, toys, handicrafts and other industries. Such as in the car rearview mirror, headlight regulator, timer, micro motor, reducer, printer, fax machine, camera, DVD movement, shredder, copier, massager, toy movement, instrumentation, medical equipment Different gear combinations are used in products such as vacuum cleaners and automatic coffee machines.  The causes of gear system noise mainly include the following aspects: 1. Gear design: improper parameter selection, too small coincidence, improper or no shape modification, and unreasonable gearbox structure. 2. Gear processing: the base section error and the tooth profile error are too large, the tooth side clearance is too large, and the surface roughness is too large. 3, the wheel train and gear box: assembly eccentricity, low contact accuracy, shaft parallelism, shaft, bearing, support stiffness is not enough, the bearing's rotation accuracy is not high and the gap is not appropriate. 4. Input torque in other aspects. Fluctuation of load torque, torsional vibration of the shafting, balance of the motor and other transmission pairs, etc.