Miniature Ball Bearing Noise and Testing for Bearing Noise || Dynaroll

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

DYNAROLL CODE	NOISE TESTING LEVEL
No Code	Standard bearing - not noise tested
E	Noise tested to meet electric motor quality quietness standards.
ER	Ultra low noise tested to spindle motor quietness standards.