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  BEARING NOISE  

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.

NOISE TESTING

The standard instrument used for bearing noise testing is the Anderon Meter (sometimes called Anderometer) made by Sugawara Laboratories. This measures noise with an accelerometer contacting the outer race of the bearing while the inner race is rotated at 1800 RPM. Noise levels are separated into 3 bands, designated as follows:

High band             1,800 - 10,000 Hz
Medium band        300 - 1,800 Hz
Low band              50 - 300 Hz

According to the type of bearing (material and noise grade), a different attenuation is used for each band. Meters are calibrated in Anderons. Standard testing procedure requires that bearings are washed clean of any lubricant and 2 drops of fresh MIL-L-6085A oil lubricant added prior to testing.

Typical attenuation values for each band are given in the table below, according to bearing material and noise grade. A "pass" for any bearing grade is defined as < 40% of full scale on the Anderon meters for each band. In this case, this translates to pass levels of
Low < 6.4, Med < 2.4, High < 3.2.

Anderon Meter attenuation settings:
Material Noise
rating
Low
band
Mid
band
High
band
52100
chrome
steel
None 16 6 8
E 16 6 8
ER 12 6 8
440C/
Martensitic
stainless
None 16 10 24
E 16 10 24
ER 16 8 10
ANDERON meter < 40% = Good bearing


BEARING NOISE LEVEL GRADES

DYNAROLL CODENOISE TESTING LEVEL
No CodeStandard bearing - not noise tested
ENoise tested to meet electric motor quality quietness standards.
ERUltra low noise tested to spindle motor quietness standards.


Above codes apply to industry standard part numbering system. See link below:

Bearing part numbering system







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