HOW TO READ BEARING NUMBERS.

When referring to bearing numbers, we are referring to the bearing designation or part number often etched or stamped on the inner ring of the bearing. This is a standardised alphanumerical code that conveys essential information about the bearing including type, load series, bore size, seal and clearance. 

The commonly used bearing numbering system is the ISO (International Organisation for Standardisation) bearing designation system, which is widely followed by manufacturers worldwide. There is also the original ABMA (American Bearing Manufacturers Association) numbering system that is still used by some manufacturers.

Below are some examples of two common bearings. 

6 - denotes the bearing type and in this example is a single-row deep groove ball bearing

3 - is the load series

05 - represents the bore size, which is 5mm multiplied by the last two digits (5 x 5 = 25mm)

2RS - is a suffix that indicates the bearing has two rubber seals (RS = Rubber Seal) on both sides of the bearing to protect it from contaminants and retain lubricant

C3 - is the clearance and is greater than the normal

6 = single-row deep groove ball bearing

3 = medium load series in the 63xx range of bearings

04 = 20mm

2Z = double shielded

C3 = clearance is greater than normal

Please note that there are many different ball bearing types, series, and suffixes. This is just a general overview, and specific bearings may have unique numbering systems depending on the manufacturer and application.  For example, bearing numbers will have additional letters and numbers at any part of the code, this often means it is a specialised bearing or is specific to the bearings’ application.  An example is a letter ‘M’ between position 8 and 9 denotes the bearing has a brass cage.