Bearing knowledge include bearing inner diamater calculation, bearing precision and internal clearance.
Bearing Inner Diameter：
| ID（mm） |
ID Code（mm） |
For Example |
| 10 |
0 |
6201 Bearing, 01 stands for bearing ID is 12mm |
| 12 |
1 |
| 15 |
2 |
| 17 |
3 |
|
| 20~480 |
Bearing ID= ID Code*5 |
6205 Bearing , 05 standars for bearing ID is 25mm |
Bearing Knowledge- Bearing Precision：
Bearing precision, in other words dimensional accuracy and rotation accuracy, has corresponding international standards and national standards.
National standards for different countries are consistent with international standard.
| Country |
Standard |
Precision |
| China |
GB/T307.1 |
P0 |
P6 |
P5 |
P4 |
P2 |
| USA |
ANSI/AFBMA Std.20 |
ABEC-1 |
ABEC-3 |
ABEC-5 |
ABEC-7 |
ABEC-9 |
| Japan |
JIS B 1514 |
0 |
6 |
5 |
4 |
2 |
| Germany |
DIN 620 |
P0 |
P6 |
P5 |
P4 |
P2 |
| International |
ISO 492 |
Class 0 |
Class 6 |
Class5 |
Class4 |
Class2 |
Internal bearing clearance refers to the amount of radial or axial displacement when either the inner ring or the outer ring is fixed, and the unfixed one is moved. Depending on the direction of movement, it can be divided into radial clearance and axial clearance.
Generally we control the radial clearance for deep groove ball bearings , while we control axial clearance for double row angular contact ball bearings.
For deep groove ball bearings, radial clearance is as below,
| Bearing ID(mm) |
C2 |
C0 |
C3 |
C4 |
C5 |
| ＞ |
≤ |
min |
max |
min |
max |
min |
max |
min |
max |
min |
max |
| 2.5 |
10 |
0 |
7 |
2 |
13 |
8 |
23 |
14 |
29 |
20 |
37 |
| 10 |
18 |
0 |
9 |
3 |
18 |
11 |
25 |
18 |
33 |
25 |
45 |
| 18 |
24 |
0 |
10 |
5 |
20 |
13 |
28 |
20 |
36 |
28 |
48 |
| 24 |
30 |
1 |
11 |
5 |
20 |
13 |
28 |
23 |
41 |
30 |
53 |
| 30 |
40 |
1 |
11 |
6 |
20 |
15 |
33 |
28 |
46 |
40 |
64 |
| 40 |
50 |
1 |
11 |
6 |
23 |
18 |
36 |
30 |
51 |
45 |
73 |
| 50 |
65 |
1 |
15 |
8 |
28 |
23 |
43 |
38 |
61 |
55 |
90 |
| 65 |
80 |
1 |
15 |
10 |
30 |
25 |
51 |
46 |
71 |
65 |
105 |
| 80 |
100 |
1 |
18 |
12 |
36 |
30 |
58 |
53 |
84 |
75 |
120 |
For double row angular contact ball bearings, axial clearance is as below,
| Bearing ID (mm) |
C2 |
C0 |
C3 |
| ＞ |
≤ |
min |
max |
min |
max |
min |
max |
| — |
10 |
1 |
11 |
5 |
21 |
12 |
28 |
| 10 |
18 |
1 |
12 |
6 |
23 |
13 |
31 |
| 18 |
24 |
2 |
14 |
7 |
25 |
16 |
24 |
| 24 |
30 |
2 |
15 |
8 |
27 |
18 |
37 |
| 30 |
40 |
2 |
16 |
8 |
29 |
21 |
40 |
| 40 |
50 |
2 |
18 |
11 |
33 |
23 |
44 |
| 50 |
65 |
3 |
22 |
13 |
36 |
26 |
48 |
| 65 |
80 |
3 |
24 |
15 |
40 |
30 |
54 |
| 80 |
100 |
3 |
26 |
18 |
46 |
35 |
63 |
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