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 manufacuring techniques. These greases are more finely filtered and contain fewer, smaller solid particles. TheseVIBRATION AND NOISE

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

  d	                V			           V1			          V2			V3			V4
　
mm	Low	Medium	High	Low	Medium	High	Low	Medium	High	Low	Medium	High	Low	Medium	High
　	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand	Brand
3,4	80	44	44	60	35	32	48	26	22	31	16	15	28	10	10
5,6	110	72	60	74	48	40	58	36	30	35	21	18	32	11	11
7,8,9	130	96	80	92	66	54	72	48	40	44	28	24	38	12	12
10,12	160	120	100	120	80	70	90	60	50	55	35	30	45	14	15
15	210	150	120	150	100	85	110	78	60	65	46	35	52	18	18
17	210	150	120	150	100	85	110	78	60	65	46	35	52	25	25
20	260	190	150	180	125	100	130	100	75	80	60	45	60	25	25
22,25	260	190	150	180	125	100	130	100	75	80	60	45	60	30	32
28	260	190	150	180	125	100	130	100	75	80	60	45	60	35	40
30,32	300	240	190	200	150	130	150	120	100	90	75	60	70	35	40
35	300	240	190	200	150	130	150	120	100	90	75	60	70	42	45
40	360	300	260	240	180	160	180	150	130	110	90	80	82	50	50
45	360	300	260	240	180	160	180	150	130	110	90	80	82	60	60
50	420	320	320	280	200	200	210	160	160	125	100	100	95	70	70

imum vibration acceleration of single bearing Tolerance in dB

d	Diameter Series(0)				Diameter Series(2)					Diameter Series(3)
mm	Z	Z1	Z2	Z3	Z	Z1	Z2	Z3	Z4	Z	Z1	Z2	Z3	Z4
3	35	34	32	28	36	35	32	30	_	37	36	33	31	_
4	35	34	32	28	36	35	32	30	_	37	36	33	31	_
5	37	36	34	30	38	37	34	32	_	39	37	35	33	_
6	37	36	34	30	38	37	34	32	_	39	37	35	33	_
7	39	38	35	31	40	38	36	34	_	_	_	_	_	_
8	39	38	35	31	40	38	36	34	_	_	_	_	_	_
9	41	40	36	32	42	40	37	35	_	_	_	_	_	_
10	43	42	38	33	44	42	39	35	30	37	44	40	37	32
12	44	43	39	34	45	43	39	35	30	47	45	40	37	32
15	45	44	40	35	46	44	41	36	31	48	46	42	38	33
17	46	44	40	35	47	45	41	36	31	49	47	42	38	33
20	47	45	41	36	48	46	42	38	33	50	48	43	39	34
22	47	45	41	36	48	46	42	38	33	50	48	43	39	34
25	48	46	42	38	49	47	43	40	36	51	49	44	41	37
28	49	47	43	39	50	48	44	41	37	52	50	45	42	38
30	49	47	43	39	50	48	44	41	37	52	50	45	42	38
32	50	48	44	40	51	49	45	42	38	53	51	46	43	39
35	51	49	45	41	52	50	46	43	39	54	52	47	44	40
40	53	51	46	42	54	52	47	44	40	56	54	49	45	41
45	55	53	48	45	56	54	49	46	43	58	56	51	47	44
50	57	54	50	47	58	55	51	48	45	60	57	53	49	46
55	59	56	52	49	60	57	53	50	47	62	59	54	51	48
60	61	58	54	51	62	59	54	51	48	64	61	56	53	50

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