Bearing codes represent the basic type, structure, size and other related information about the bearing. The bearing type is usually provided to the supplier in the form of a designation for purchasing and supply. Bearing users also perform maintenance and replacement tasks based on bearing designations.
As standard parts, most bearings are covered by general designations. Only a small number of custom special bearings will have the bearing manufacturer add corresponding special designations.
Therefore, it is necessary to understand the general rules for designating bearings.
The bearing designation system used in our country is compatible with international standards. Therefore, most of the basic designation methods apply to domestically produced bearings and imported products. This article presents in accordance with the domestic bearing designation standard GB/T272.
Bearing Designation System
The bearing designation represents the basic information of the bearing, such as basic type, structure and size. A typical bearing designation includes a prefix, a basic bearing designation, and a suffix. The prefix mentioned in daily use refers to the bearing prefix, and the suffix refers to the bearing suffix.
Among them, the basic bearing designation is the most important part of the bearing designation, which contains information about the bearing type, width series, diameter series and hole information.
The structure of the bearing designation system is shown in the table below. When users encounter an unknown direction sign, they can obtain a basic understanding of some information through the table structure below.
| Bearing designation | |||||
| Prefix designation | Basic Designation | Suffix designation | |||
| Bearing Series | Inner diameter designation | ||||
| Type designation | Dimension series designation | ||||
| Width (or height) series designation | Diameter series designation | ||||
The bearing prefix
The bearing prefix is used to represent some bearing components. The basic bearing prefixes are defined in GB/T272.
| Designation | Meaning |
| I | Removable inner or outer ring of a separable bearing |
| LR | Components with removable inner or outer ring and rolling elements |
| R | Components without detachable inner or outer ring (needle bearings are only applicable for NA type) |
| K | Roller and cage assembly |
| W.S. | Axial cylindrical roller bearing shaft ring |
| GS | Cylindrical roller thrust bearing seat ring |
| F | Self-aligning bearing with flanged outer ring (only applicable for d≤10mm) |
| Federal Security Service | Separable micro angular contact ball bearing with flanged outer ring (only applicable for d≤10mm) |
| KIW | Thrust bearing assembly without seat ring |
| FIND OUT | Thrust bearing assembly without shaft ring |
In certain common bearings, there may be no specialized designs and consequently the bearing prefix code may be omitted.
Basic Bearing Codes
The basic code of a bearing is the main part of the bearing code and is the final section of the bearing code. Bearing users, through the basic code, can at least understand what type of bearing it is, its size and an approximate level of its load capacity.
Among these, the bearing type code is the most crucial. It consists of numbers or letters and is in the main part of the basic bearing code. Specific meanings are described in the table below:
| Designation | Types of bearings | Designation | Types of bearings |
| 0 | Double Row Angular Contact Ball Bearings | N | Cylindrical roller bearings |
| 1 | Self-aligning ball bearings | Double-row or multiple-row bearings, indicated by the letters NN | |
| two | Spherical roller bearings and spherical roller thrust bearings | you | Spherical roller bearings |
| 3 | Tapered roller bearings | QJ | Four-point contact ball bearings |
| 4 | Double row deep groove ball bearings | W | Long arc roller bearings (also known as toroidal bearings) |
| 5 | Thrust ball bearings | ||
| 6 | Deep groove ball bearings | ||
| 7 | Angular Contact Ball Bearings | ||
| 8 | Cylindrical roller thrust bearings | ||
| Note: Adding letters or numbers before or after the code indicates different structures within that bearing class. | |||
A bearing's dimensional series code represents its basic dimensions, which include the width and bearing diameter (outer diameter), as detailed in GB/T272.
A bearing's bore code is an important part of the bearing designation, representing the bore diameter and serving as a critical reference for bearing selection. There are certain rules to follow for bearing bore code to make it easy to remember as shown in the table below:
| Nominal bearing inner diameter in mm | Hole code | Example | |
| 0.6~10 (not integers) | Indicated directly by the nominal hole diameter in millimeters, separated from the size serial code by a “/”. | Deep Groove Ball Bearing 617/0.6 Diameter 0.6mm
Deep Groove Ball Bearing 618/2.5 Diameter 2.5mm |
|
| 1~9 (Integers) | For deep groove ball and angular contact bearings with diameter series 7, 8, 9, the bore diameter is indicated directly in millimeters, separated from the size series code by a “/”. | 625 Deep Groove Ball Bearing Diameter 5mm
Deep Groove Ball Bearing 618/5 Diameter 5mm 707 Angular Contact Ball Bearing Diameter 7mm 719/7 Angular Contact Ball Bearing Diameter 7mm |
|
| 10~17 | 10 | 00 | 6200 Deep Groove Ball Bearing 10mm Diameter |
| 12 | 01 | 1201 Self-Aligning Ball Bearing Diameter 12mm | |
| 15 | 02 | NU202 Cylindrical Roller Bearing Diameter 15mm | |
| 17 | 03 | Axial ball bearing 51103 diameter 17mm | |
| 20~480 (excluding 22, 28, 32) | The quotient of the nominal inside diameter divided by 5, if a single-digit number, requires the addition of a “0” to the left, such as 08. | 22308 Spherical Roller Bearing with 40mm diameter
NU1096 Cylindrical Roller Bearing Diameter 480mm |
|
| ≥500 as well as 22, 28, 32 | The nominal inner diameter in millimeters must be represented directly, but must be separated from the size series by a “/”. | Spherical roller bearing 230/500 with diameter 500mm
Deep Groove Ball Bearing 62/22 Diameter 22mm |
|
Bearing Suffix Designation
The bearing suffix designation encompasses a multitude of supplementary information beyond the basic type and dimension details of the bearings. The specific structure is as follows:
| Group | Meaning |
| 1 | Internal structure |
| two | Externally shaped sealing and dust protection |
| 3 | Retainer and its material |
| 4 | Bearing parts material |
| 5 | Tolerance level |
| 6 | Release |
| 7 | Settings |
| 8 | Vibration and Noise |
| 9 | Others |
The bearing postfix is positioned after the basic code, separated by half a space (except for codes with “-“, “/”), and the content sequence follows the rules in the table above.
Changes to content starting from group 4 (including group 3) are separated by “/”. If the changes involve the two groups after group 4, and the numeric or textual identifiers in the codes of the previous and following groups may cause confusion, they will be separated by a half-character space.
Bearing suffixes have related national standards, and some imported brands also have their own suffix identifiers. Although the text of the identifiers may differ, the sequence rules remain largely unchanged.
Given the large number of brands, when finding special suffixes, it is necessary to consult the respective manufacturers' product manuals for confirmation. However, a general understanding of the above structure aids in the interpretation of bearing suffixes.
