High Precision Ball Bearings - Kraftmek

Bearing calculation
The method of calculation described as follows is an extract from DIN/ISO 76 (static load rating) and DIN/ISO 281
(dynamic load rating, life rating).
1. Definition of dynamic load rating C
for two or more spindle bearings in DF, DB or DT arrangement:
C = i 0,7 · C single bearing [N]
i
: Number of bearings in bearing set
C single bearing : Load rating of single bearing [N]
2. Definition of equivalent dynamic load P
P = X · F r + Y · F a [N]
X,Y : Radial factor, axial factor
F r ,F a : Radial load, axial laod [N]
The preload of the bearing must be taken into consideration:
1. If K a 3 · F v then use F a = F v + 0.67 · K a [N]
2. If K a > 3 · F v then use F a = K a [N]
K a : external axial load [N]
F v : Preload of a bearing set [N]
3. Definition of X and Y factors
Relative Single bearing Bearing pair
in axial load DT arrangement 2) DF or DB arrangement
i · F a / C 0 1)
e F a / F r e F a / F r > e F a / F r e F a / F r > e
X Y X Y X Y X Y
Spindle bearing 0.015 0.38 1.47 1.65 2.39
0.029 0.40 1.40 1.57 2.28
Contact angle 15 ° 0.058 0.43 1.30 1.46 2.11
0.087 0.46 1.23 1.38 2.00
0.120 0.47 1 0 0.44 1.19 1 1.34 0.72 1.93
0.170 0.50 1.12 1.26 1.82
0.290 0.55 1.02 1.14 1.66
0.440 0.56 1.00 1.12 1.63
0.580 0.56 1.00 1.12 1.63
Spindle bearing
Contact angle 25 °
0.68 1 0 0.41 0.87 1 0.92 0.67 1.41
Deep groove bearing 0.014 0.23 2.30 2.78 3.74
Standard radial play 0.028 0.26 1.99 2.40 3.23
0.056 0.30 1.71 2.07 2.78
0.085 0.34 1.55 1.87 2.52
0.110 0.36 1 0 0.56 1.45 1 1.75 0.78 2.36
0.170 0.40 1.31 1.58 2.13
0.280 0.45 1.15 1.39 1.87
0.420 0.50 1.04 1.26 1.69
0 .560 0.52 1.00 1.21 1.63
Deep groove bearing 0.014 0.29 1.88 2.18 3.06
radial play C3 0.029 0.32 1.71 1.98 2.78
0.057 0.36 1.52 1.76 2.47
0.086 0.38 1.41 1.63 2.29
0.110 0.40 1 0 0.46 1.34 1 1.55 0.75 2.18
0.170 0.44 1.23 1.42 2.00
0.290 0.49 1.10 1.27 1.79
0.430 0.54 1.01 1.17 1.64
0.570 0.54 1.00 1.16 1.63
1) C 0 : Static load rating (N)
2) For DT arrangement set i=1 and use F a and C o values related to single bearing
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