Bearing designation

To identify a bearing, it’s assigned a standardized code referred to as a designation. The designation is made up of one to three parts;

• Prefix
• Basic designation
• Suffix

Prefixes and suffixes, which provide additional information to the designation, are not always included.

The meaning of the numbers and letters that can be included in a designation is listed in the section Code tables below.

Basic designation

A basic designation contains 3-5 digits that always represent these three pieces of information:

• Bearing type,
• Bearing series, and
• Bore size (inner diameter).

Note: the Bearing type and Bearing series put together is called Bearing series.

Let’s take the following three designations as examples

• 626 (3 digit designation)
• 6305 (4 digit designation)
• 62103 (5 digit designation)

626

• The first digit always tells us the Bearing type (6 = Single row deep ball groove bearing.)
• The second digit (2) tells us the Dimension series (2 = Light).
• In a three digit designation, the third digit (6) tells us the Bore size in mm. So in this case, the Bore diameter is 6 mm.

6305

• Again, the first digit tells us the Bearing Type (6 = Single row deep ball groove bearing.)
• The second digit (3) tells us the Bearing series (3 = Medium.)
• The third and fourth digit (05) tells us the Bore size (05 = 25 mm.)

62103

• First digit for Bearing type as always.
• The second and third digit tells us the Dimension series where
  • the second digit (2) is the width code and
  • the third digit (1) is the diameter series
• The fourth and fifth digits (03) tells us the bearing Bore size (03 = 17 mm.)

Prefixes and suffixes

A bearing code can also be made longer to include additional information such as;

• Shield code
• Contact angle code
• Matched pair or stack code
• Internal design code
• External configuration code
• Bearing ring shape code
• Internal clearance code
• Tolerance class code

Code tables

Prefix codes

Prefix Code	Meaning
K	Cage with roller elements
L	Removable bearing ring
R	Ring with roller set
S	Roll body of stainless steel
W	Stainless steel deep groove ball bearing
H,LM	Tapered Roller Bearings-Inch
HJ,IR	Needle Roller Bearings-Inchstvle
K	Needle Roller Bearings-Metric
N, NJ, NU,NUP	Cvlindrical Roller Bearings-Metric
NA,NAO	Needle Roller Bearings with Inner Rings-Metric
NK,RNA	Needle Roller Bearings without Inner Rinos-Metric
NN	Super Precision Cylindrical Roller Bearings

Additional designation examples

Here are some examples what bearing designations can look like. (What the codes mean is shown under section Code tables below. 6305ZZ