TOLERANCE
　　 Bearing tolerance includes dimensional tolerance and revolving tolerance, Dimensional tolerance is a request when bearings are mounted on shafts or in housings. It includes bore/outerside diameter deviation from basic, inner ring/outer ring width deviation in single radial plane. Revolving tolerance includes radial and axial runout of assembled bearing inner ring and outer ring, inner ring reference fcace runout with bore and outside cylindrical surface runout with outer reference face.
　　Tolerance class ranges from common class 0 to 6,5,4 and 2, from low to high, Table 1 below is the tolerance class stipulated in China GB307 and its comparison with some other standards.

COMPARISON OF TOLERANCE CLASS

CLEARANCE

　　Bearing clearance means the value of displacement of the unfixed ring when it moves against the fixed ring in radial or axial direction before the bearing is mouted on a shaft or in a housing. According to the movement direction, it falls into radial clearance and axial clearance.

RADIAL CLEARANCE

VIBRATION

　　Bearing vibration means bearing components’ elastic deformation that varies with time and all other movement that deviates from a theoretic position except that necessary to bearing functions. It has two modes-acceleration(dB)and velocity(μm/S), Vibration acceleration is examined according to Z, Z4, Z2, and Z3 values. Grade Z is fundamental, Z1, Z2&Z3 successively indicate the vibration level ranges fron low to high. For detailed requirements, see Table3. Simlary, viaration velocity is examined as per V, V1, V2&V3. Grade V is fundamental, V1, V2&V3 successively indicate the vibration level ranges from low to high. For details, see Table4. Generally, velocity examination is better than acceleration examination in that it can more reflect bearings’ manufacturing level and bearings’ inherent quality.
While our company keeps control of vibration velocity values, we also carry out vigorous control on abnormal noise from running bearings in test according to requirements of electric motor quality bearings.

VIBRATION(ACCELERATION) LIMITES FOR SINGLE BEARING dB

VIBRATION (VELOCITY)LIMTES FOR SINGLE BEARING μm/s