High Precision Ball Bearings - Kraftmek

Form and running accuracy
Low vibration level and high running accuracy are ensured
by random sample production control on the rings and
the balls. Form accuracy and surface finish are checked
by using advanced precision measuring instruments,
the runouts of assembled bearings are checked 100%.
Apart from highly advanced manufacturing machines
constant production control ensures the uniform quality
of GMN high precision ball bearings.
Sophisticated measuring systems and quality assurance
methods ensure a high degree of accuracy, low friction,
a high degree of quiet running, highest speeds and a
long service life.
Vibration
The vibration level depends, among other things, on:
• Form accuracy and surface finish of raceways and
balls
• Cage design
• Cleanliness and method of lubrication
Ball pass frequency f AR on the outer ring
Z
f AR = · f i ·
2
Ball pass frequency f iR on the inner ring
Z
f iR = · f i ·
2
D
1 – W
cos
T 0 [1/sec]
D
1 + W
cos
T 0 [1/sec]
A 100% vibration test is carried out with all GMN high
precision ball bearings. The spectral analysis carried out
regularly by taking random samples gives information
on the inner and outer ring as well as ball form accuracy.
The vibration spectrum of a ball bearing is essentially
discreet, the dominating frequencies are design related.
The specific frequencies of a bearing can be calculated
with the aid of the formulae shown opposite.
Ball spin frequency f w
f
f w = i T D
· – W
cos 2
2 T
0 [1/sec]
D W
Cage rotation frequency f K
f
f K = i D
· 1 – W
cos
2 T 0 [1/sec]
f i
= Shaft frequency 1/sec
D w
= Ball diameter in mm
T = Pitch diameter in mm
Z = Number of balls
0
= Contact angle
…about the product
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