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A bearing number is made up of many numbers that represent various characteristics of a bearing. A bearing number, in general, contains information on bearing types, bearing series, bore size, and sealing basic designation typically contains three to five digits.
The first digit of the bearing refers to the type of bearing.
The second digit identifies the bearing series.
The last two digits of the basic designation identify the size code of the bearing bore. The size code multiplied by 5 gives the bore diameter (d) in mm.
For instance, let’s take an example 6310. How can we know more about the bearing base on the number?
The first number, ‘6’ represents the bearing being a deep groove bearing.
The second digit ‘3’ bearing series refers to the bearing toughness, which is medium.
The last two digits represent the bore size of the bearing. We can get the diameter by multiplying by five to provide us with a clear diameter(d) in mm. This is one of the ways to identify one of the ball bearing sizes by looking at the designation code. So we can conclude that the inner diameter of the 6310 is 50 mm. In bearing number, the last digit or last second digit if it has 5 digits, can indicate the bearing size.
The table will help to identify types of bearings by number. Types of bearing and their codes.
| Deep Groove Ball Bearing | 6 |
| Cylindrical Roller Bearing | N |
| Tapered Roller Bearing | 32/T |
| Spherical Roller Bearing | 2 |
The table will help to identify types of bearing series toughness.
| Extra Light | 0 |
| Extra Light Thrust | 1 |
| Light | 2 |
| Medium | 3 |
| Heavy | 4 |
| Extra thin section | 8 |
| Very thin section | 9 |
How do we find bearing numbers?
One of the simplest ways to find the bearing number is to look for designation numbers. They are often engraved on the bearing’s surface. However, if they have been employed for a long time, the designation number may be wiped away owing to wear. To know the designation number, we can take its inner diameter divided by five.
