The designations of most SKF rolling bearings follow a bearing designation system. The complete SKF bearing nomenclature may consist of a basic designation with or without one or more supplementary designations. The complete designation is always marked on the bearing package, whereas the marking on the bearing may be incomplete or deviate from the designation. The basic designation identifies:
- SKF bearing type
- SKF basic design
- the boundary dimensions
Prefixes and suffixes identify bearing components or variants having a design and/or feature(s) that differ in some respect from the basic design.
Designations for SKF rolling bearings
SKF basic designations
|Code||Bearing type||Code||Bearing type||Code||Bearing type|
|0||Double row angular contact ball bearing||7||Single row angular contact ball bearing||QJ||Four-point contact ball bearing|
|1||Self-aligning ball bearing||8||Cylindrical roller thrust bearing||T||
Tapered roller bearing
in accordance with
|2||Spherical roller bearing, spherical roller thrust bearing||C||CARB toroidal roller bearing|
|3||Tapered roller bearing||N||Cylindrical roller bearing. Two or more letters are used to identify the number of the rows or the configuration of the flanges, e.g. NJ, NU, NUP, NN, NNU, NNCF etc.|
|4||SKF double row deep groove ball bearing|
|5||Thrust ball bearing|
|6||SKF single row deep groove ball bearing|
A basic SKF designation typically contains three to five digits. Some products, like cylindrical roller bearings, can have a combination of alphanumeric characters. The number and letter combinations have the following meaning:
- The first digit or letter or combination of letters identifies the bearing type and eventually a basic variant.
- The following two digits identify the ISO dimension series. The first digit indicates the width or height series (dimensions B, T or H). The second digit identifies the diameter series (dimension D).
- 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.
SKF diameter series designations
|Bearing type||Diameter series|
|7, 8, 9||0, 1||2, 3, 4|
Deep groove ball bearings1)
||617, 618, 619||60||2, 3|
|627, 628||160, 161||42, 43|
|637, 638, 639||630||62, 63, 64, 622, 623|
Angular contact ball bearings
|QJ 2, QJ 3|
|Self-aligning ball bearings2)||139||10, 130||12, 13, 112|
Cylindrical roller bearings
||NU 10, 20||NU 2, 3, 4, 12, 22, 23|
|NJ 10||NJ 2, 3, 4, 22, 23|
|NUP 2, 3, 22, 23|
|N 2, 3|
|Needle roller bearings||NA 48, 49, 69|
|Full complement cylindrical||NCF 18, 19, 28, 29||NCF 30||NCF 22|
||NNC 48, 49||NNF 50||NJG 23|
|NNCF 48, 49||NNCF 50|
|NNCL 48, 49|
|Spherical roller bearings||238, 239||230, 231||222, 232|
|248, 249||240, 241||213, 223|
|CARB toroidal roller bearings||C 39, 49, 59, 69||C 30, 31||C 22, 23|
|C 40, 41||C 32|
1) Bearings 604, 607, 608, 609 belong to diameter series 0,
bearings 623, 624, 625, 626, 627, 628 and 629 to diameter series 2,
bearings 634, 635 and 638 to diameter series 3
bearing 607/8 to diameter series 9
2) Bearing 108 belongs to diameter series 0,
bearings 126, 127 and 129 to diameter series 2,
bearing 135 to diameter series 3
The most important exceptions in the basic bearing designation system are:
- In a few cases the digit for the bearing type or the first digit of the dimension series identification is omitted.
Bearings with a bore diameter of 10, 12, 15 or 17 mm have the following size code identifications: e.g. 6300-2RSH (d=10mm)
00 = 10 mm
01 = 12 mm
02 = 15 mm
03 = 17 mm
- For bearings with a bore diameter < 10 mm, or ≥ 500 mm, the bore diameter is generally given in millimetres (uncoded). The size identification is separated from the rest of the bearing designation by an oblique stroke, e.g. 628/8-2Z (d = 8 mm) or 511/530 (d = 530 mm). This is also true of standard bearings in accordance with ISO 15:2011 that have a bore diameter of 22, 28 or 32 mm, e.g. 62/22 (d = 22 mm).
- For some bearings with a bore diameter < 10 mm, such as deep groove, self-aligning and angular contact ball bearings, the bore diameter is also given in millimetres (uncoded) but is not separated from the series designation by an oblique stroke, e.g. 608-2RSH/C3 (d=8mm) 629 or 129 (d = 9 mm).
- Bore diameters that deviate from the standard bore diameter of a bearing are uncoded and given in millimetres up to three decimal places. This bore diameter identification is part of the basic designation and is separated from the basic designation by an oblique stroke, e.g. 6202/15.875 (d = 15,875 mm = 5/8 in).
Each standard bearing belongs to a given bearing series, which is identified by the basic designation without the size identification. Series designations often include a suffix A, B, C, D or E or a combination of these letters. These letters are used to identify differences in internal design.
SKF bearing designations not covered by the basic system
The designations for certain SKF bearing types are either not covered, or are only partially covered.
SKF Y-bearings (insert bearings)
The designations for SKF Y-bearings differ somewhat from those described in the basic designation system and are covered in the relevant product section.
SKF Needle roller bearings
The designations for needle roller bearings do not fully follow the basic designation system and are covered in the relevant product section.
SKF tapered roller bearings
The designations for metric tapered roller bearings follow either the basic designation system or a designation system, established by ISO in 1977, covered in ISO 355:2007
Inch tapered roller bearings are designated in accordance with the relevant ANSI/ABMA standard. The designation system for tapered roller bearings is explained in the relevant product section.
SKF customized bearings
Bearings designed to meet a specific customer requirement are typically designated by a drawing number. The drawing number does not provide any information about the bearing.
SKF other rolling bearings
SKF rolling bearings not covered in the Ball bearings and Roller bearings sections, such as super-precision bearings, thin section bearings, slewing bearings or linear bearings, follow designation systems that can differ significantly from the basic designation system.
SKF bushing bearings
The designation for SKF bushing bearings identifies SKF bushings type, size, material, and lubrication.