How to Identify Bearings

With an understanding of the Nomenclature and some trivial calculations, it is relatively simple to decode the key/relevant details and to identify what is needed.

By the end of reading this, you will be unimpressed with the claim, and (be able to verify it) that Bearing “6305ZZ is a Single row deep groove ball bearing having medium toughness, with a bore size of 25 mm and is shielded from both sides.“

The Bearing Code or Pattern Number is an alphanumeric code where each number/digit (or combinations) in the sequence, represents some attribute of the bearing and means something.

By and large, this convention is adhered to world-wide, at worst some of the digits might be omitted, but this is because that particular piece of information is superfluous, to a particular application. The best way to proceed is with an example.

Worked Example - 6305ZZ

As the picture above illustrates we break the 6 characters of the Bearing Number down into the following:

The 1^st digit - Represents the Type of Bearing
The 2^nd digit - Represents the Bearing Series
The 3^rd and 4^th digits - Contain Information on the Bore Size
The 5^th and 6^th characters - Contain data on the Sealing of the Bearing

Bearing Types

So our first digit ¨6¨ stands for a ‘Single row deep groove ball bearing’.

Actually, it is better to say that a)The Type Code appears first in the Bearing Code sequence, it can be a single digit or longer, a combination of characters. Whatever it is, it must originate from the list provided, there are 18 from which to choose.

Bearing Series

Next we have the bearing series which merely denotes the toughness of the bearing.

So our next digit ¨3¨ stands for ‘Medium’ toughness.

Toughness in this context .

Bore Sizes

The third and fourth digit of the Bearing Pattern Number indicate the bore size of bearing and this corresponds to the Inner Diameter of the bearing, values are given in mm.

In general, the bore size is equal to five times the third and forth digit of bearing’s patter number. However, from ‘0’ to ‘3’, this formula does not apply, as the table indicates. So for our worked example, the third and fourth digit ‘05’ means the bearing’s bore size is 5x5=25 mm.

For bore diameters from 500mm inclusive and larger, after the part of the initials that indicates the Dimensional Series, there will be a slash (/), followed by the diameter of the bore in millimetres. Example: 62/500.

Note: In those cases where there is no fourth digit, then the 3rd digit indicates the bore size in mm. For example: in case of bearing 636, the bore size of the bearing will be 6mm.

Shielding and Sealing

So for our example, bearing 6305ZZ, the last letters ‘ZZ’ means the bearing is shielded from both sides.