Bearing acoustical noise is a function of both the bearing itself and the way in which it is used. Bearings can be specified as 100% noise-tested during manufacture. Bearing noise is not generally influenced by ABEC precision, but rather by manufacturers’ internal quality standards, particularly raceway finish. There are no fixed reference standards among manufacturers for noise testing

External factors affecting bearing noise include lubricant type, excessive load, improper fitting, preload method, and other factors. In particular, it is recommended that the stationary ring always be securely immobilized during high speed rotation

Vibration acceleration is an indication of vibratory force (force = mass x acceleration) and since force is damaging at higher frequencies, vibration acceleration is a useful measurement where a bearing will experience vibration frequencies above 2000 Hz. Vibration acceleration is measured in G (1G being the acceleration produced by the Earth's gravity or 9.81 m/s2) but you will often see these measurements converted to decibels (dB). These decibel measurements are usually classified into Z grades (Z1, Z2, Z3 or Z4). Bearings can be classified according to both vibration velocity AND vibration acceleration levels (ZV1, ZV2, ZV3 or ZV4).

A low noise/vibration rating is achieved by paying particular attention to the surface finish of the raceways and balls, the roundness of the rings and balls and correct cage design. We have three ratings for EMQ low noise bearings: EMQ (ZV2), EMQ2 (ZV3) and the quietest, EMQ3 (ZV4). These ratings are independent of precision grade, for example, a P6 bearing may be offered with any of the three noise ratings. To help reduce noise levels even further, low noise greases are available and the choice is now greater due to improved lubricant manufacturing techniques. These greases are more finely filtered and contain fewer, smaller solid particles.

The vibration and noise of bearings are classified as four classed as Z1,Z2,Z3 and Z4.It is measured by the instrument of S0910-1,For special requirement,it is measured by BVT-1 and classified as V1, V2, V3 and V4.The data are shown as below. Customer need mark their requirement of vibration and noise class on the order.

Tolerance data for vibration of single bearing                                       Tolerance in um/s 

Maximum vibration acceleration of single bearing                                        Tolerance in dB 

Particles generate noise when they pass between the balls and raceway.