Views: 0 Author: Site Editor Publish Time: 2025-02-12 Origin: Site
In the world of bearings, bearing number carries a wealth of information, such as bearing type, bearing size, bearing tolerance, bearing precision, bearing structure, and other special features of bearings, it can be recognized to be the “identity card” of the bearing. It not only helps to select bearings but also improves the operational efficiency and reliability of the equipment by correctly understanding the bearing number means.
The specifications and types of bearings vary in countless ways. For every engineer, purchaser, and user, an in-depth understanding of the composition of the bearing model and its significance is a basic knowledge that must be mastered. Understanding the bearing code is not only beneficial to bearing selection but also vital to the normal and efficient operation of mechanical equipment.
In this article, LNB bearing company will explore in-depth from the naming rules and basic structure of the bearing number, analysis of common bearing type numbers, bearing selection points, and other dimensions, hoping to help users quickly identify the type of bearings used, and make reasonable selection decisions in practical applications.
The naming rules for bearing models vary according to the standards of different countries and manufacturers, but common standards include ISO (International Organization for Standardization), GB (Chinese national standard), DIN (German standard), JIS (Japanese standard), ANSI (American standard), and the corporate standards of national bearing manufacturers (e.g. SKF, NSK, FAG, NTN, KOYO, etc.).
Although there are details differences in the naming rules of different brands and manufacturers, the core logic is the same: through the combination of numbers and letters, systematically express the structural characteristics and performance parameters of bearings.
The basic structure of bearing model is composed of basic code and supplementary code, in which the supplementary code is divided into the prefix code and suffix code.
The supplementary prefix code is usually placed before the basic code of the bearing, which shows some special design, material, process, or application of the bearing. According to the different bearing manufacturers, the specific prefix code may be different. Some commonly used prefix codes are as follows:
(1) F: Radial ball bearings with flanged outer rings
(2) K: Roller and cage assemblies for radial or thrust cylindrical roller bearings
(3) L: Can be separated inner or outer ring bearings
(4) R: Not can be separated inner or outer ring bearings
The basic code includes bearing type, bearing structure, size series and inner diameter size, etc. It is the core part of the bearing number.
The ordinary code structure of the bearing generally includes from three to six digits or a letter-number combination. The number of the digits is normally arranged from left to right.
Radial bearing is mainly used for radial loads, i.e. the direction of the force on the bearing is parallel to the bearing axis. The nominal contact angle is in the range from 0° to 45°.
Centripetal contact bearings a = 0°; angular contact radial bearings 0 < a ≤ 45°.
Common centripetal bearings are deep groove ball bearings, cylindrical roller bearings, tapered roller bearings, etc. Centripetal bearings are widely used to stably support the rotating shaft but do not bear the axial force of machinery, such as electric motors, machine tools, pumps, automobile hubs and so on.
Bearing Type Code | Bearing Type Name |
0 | Double row angular contact ball bearing |
1 | Self-aligning ball bearing |
2 | Spherical roller bearing and thrust spherical roller bearing |
3 | Tapered roller bearing |
4 | Double row deep groove ball bearing |
5 | Thrust ball bearing |
6 | Deep groove ball bearing |
7 | Angular contact ball bearing |
8 | Thrust cylindrical roller bearing |
N | Cylindrical roller bearing |
Bearing size series code generally consists of the diameter and width series codes.
Diameter series code (arranged from right to left, usually is the third number)
Bearing diameter series refers to the same structure and inner diameter of the bearing in the outer diameter size changes in the series. Usually with figures 7, 8, 9, 0, 1, 2, 3, 4, 5, etc., the outer diameter size is in increasing order. Among them:
7: Ultra-light series
8, 9: Super-light series
0, 1: Extra light series
2: Light series
3: Medium Series
4: Heavy series
The diameter series of thrust bearing dimensions is slightly different from that of radial bearings. Where "0" indicates ultra-light series, "1 " indicates extra-light series, "2" indicates light series, "3" indicates medium series, "4" indicates heavy series, and "5" indicates extra-heavy series.
Width series code (arranged from right to left, usually is the fourth number)
Bearing width series refers to the structure, inner diameter and outer diameter series are the same, while bearing width changes in the series. Usually with figure 8, 0, 1, 2, 3, 4, 5, 6 and so on, the width of the size of the sequential increase.
Thrust bearings to height series corresponds to the width of the centripetal bearing series, height series code usually with figure 7, 9, 1, 2, etc., and height size in ascending order.
Note:
when the width series and the diameter series of the comparison is listed as 0 series (normal series), the standard centripetal ball bearings and cylindrical roller bearings in the code may not mark the width series code "0", but for spherical roller bearings and tapered roller bearings, the width series code "0" should be marked.
For bearings, the inner diameter of the calculation is very important. Usually the inner diameter is expressed by "d". The following is the judgment method of the inner diameter of the bearing.
0.6mm <d <10mm, and for the non-integer: directly expressed in "mm," and it separated by “/” from the size series code. Such as 618/1.5, the inner diameter of 1.5mm
1mm ≤ d < 10mm, and for the integer: the inner diameter is directly expressed in "mm". Such as 628 bearing, the inner diameter of 8mm.
d=10mm, 12mm, 15mm, or 17mm: the inner diameter of 10mm, the inner diameter code is “00”; the inner diameter of 12mm, the inner diameter code is “01”; the inner diameter of 15mm, the inner diameter code is “02 ”; inside diameter of 17mm, the inner diameter code for the “03”. Such as bearing 6001, the size of 12 × 28 × 8mm, the inner diameter of 12mm.
20mm ≤ d ≤ 480mm, to the inner diameter code × 5 calculated to get the value of the inner diameter. Such as 6024, bearing inner diameter is 24 × 5 = 120mm.
When d ≥ 500mm or d = 22mm, 28mm, 32mm, directly expressed in "mm", and separated by “/” from the size series code.
| Bearing Model | Type Code | Width (Height) Series Code | Diameter Series Code | Inner Diameter Code | Bearing Type | Bearing Diameter （d×D×B） |
| 625 | 6 | 【0】omit | 2 | 5 | Deep groove ball bearing | 5×16×5mm |
| 6205 | 6 | 【0】omit | 2 | 05 | Deep groove ball bearing | 25×52×15mm |
| 6010 | 6 | 【1】omit | 0 | 10 | Deep groove ball bearing | 50×80×16mm |
| 7314C | 7 | 【0】omit | 3 | 14 | Angular contact ball bearing | 70×150×35mm |
| 1209 | 1 | 【0】omit | 2 | 09 | Self-aligning ball bearing | 45×85×19mm |
| N206 | N | 【0】omit | 2 | 06 | Cylindrical roller bearing | 30×62×16mm |
| 32006 | 3 | 2 | 0 | 06 | Tapered roller bearing | 30×55×17mm |
| 30206 | 3 | 0 | 2 | 06 | Tapered roller bearing | 30×62×16mm |
| 51204 | 5 | 1 | 2 | 04 | Thrust ball bearing | 20×40×14mm |
| 22209 | 2 | 2 | 2 | 09 | Spherical roller bearing | 45×85×23mm |
| 29426 | 2 | 9 | 4 | 26 | Thrust roller bearing | 130×270×85mm |
Bearing suffix code belongs to the supplementary code, usually located behind the basic code, used to indicate and the basic design with a different structure or other special features. Such as internal structure change, ring deformation, sealing and dustproof device deformation, material change, cage change, tolerance level, clearance level, pair combination, special performance requirements and so on. Common suffix codes include:
(1) F: steel, ductile iron or powder cast iron solid cage
(2) M: brass solid cage
(3) J: steel stamping cage
(4) L: light alloy solid cage
(5) TN: engineering plastic molded cage, additional numbers indicate different materials, such as TN9.
(6) Z/ZZ: single/bilateral metal dust cover.
(7) RS/2RS: single/bilateral rubber seals.
(8) P4/P5: High precision grade (P4 is more precise than P5).
(9) C3/C4: Larger internal clearance, suitable for high speed or high temperature environment.
Deep groove ball bearing is one of the most widely used bearings, and its model numbers usually begin with “6”.
Deep groove ball bearings have deep grooves in the inner and outer rings and are suitable for radial and slight axial loads.
"6": The 608 bearing type is deep groove ball bearing
"0": The 608 bearing size series is the “0” series
"8": The 608 bearing inner diameter is 8mm
"6"：The 6203 bearing type is deep groove ball bearing
"2"：The 6203 bearing size series is “2” series
"03": The 6203 bearing inner diameter is 17mm.
(1) The common sealing forms of deep groove ball bearings include open type, 2RS (rubber seal) and ZZ (metal shield), when selecting the bearing type, it is necessary to choose the suitable protection method according to the working environment.
(2) Sealed deep groove ball bearings are usually filled with grease, and open bearings need to be refueled regularly.
Angular contact ball bearing is a kind of bearing that can bear radial and axial loads at the same time, and its model number usually starts with “7”.
The inner and outer raceways of angular contact ball bearings have a certain angle relative to each other. The angular contact ball bearing can bear radial and axial loads at the same time, and the axial load carrying capacity increases with the increase of the contact angle.
"7": The 7206 bearing type is angular contact ball bearing
"2": The 7206 bearing size series is “2” series
"06": The 7206 bearing inner diameter is 30mm (06×5=30mm)
"7": The 7309 bearing type is angular contact ball bearing
"3"：The 7309 bearing size series is “3” series
"09": The 7309 bearing inner diameter is 45mm (09×5=45mm)
(1) Angular contact ball bearing common contact angle including C (15 °), AC (25 °), B (40 °), selection should pay attention to the different angle for different working conditions. 15 ° contact angle commonly used in high-speed occasions; 25 ° contact angle of strong generality; 40 ° contact angle for high axial load.
(2) Angular contact ball bearings usually need to be mounted in pairs, such as DB (back-to-back), DF (face-to-face) or DT (tandem), in order to ensure that the force is balanced.
Self-aligning ball bearing is one of the bearings suitable for bearing radial loads and certain axial loads, and its model numbers usually begin with “1”.
The outer ring raceway of self-aligning ball bearings is spherical in shape, with automatic self-aligning function, which can compensate for the error caused by the shaft or housing not concentric, and it is suitable for the working condition where the shaft is easy to be deformed or the mounting precision is low.
"1"：The 1210K bearing type is self-aligning ball bearing
"2": The 1210K bearing size series is the “2” series
"10": The 1210K bearing inner diameter is 50mm (10×5=50mm).
"K": Indicates that the 1210K bearing has a tapered hole, which can be used for tightening sleeve mounting.
"1"：The 1306 bearing type is self-aligning ball bearing
"3": The 1306 bearing size series is “3” series
"06": The 1306 bearing inner diameter is 30mm (06×5=30mm)
(1) Self-aligning ball bearings have good self-aligning property, which can automatically compensate for the coaxiality error due to shaft deflection and shell deformation, and they are suitable for the parts in which the holes of the supporting seat cannot be strictly centered.
(2) Self-aligning ball bearings are divided into cylindrical hole and tapered hole, tapered hole self-aligning ball bearings model number with “K”, indicating that the inner hole is 1:12 tapered hole, need to cooperate with the tightening sleeve or withdrawal sleeve installation.
Thrust ball bearing is one of the ball bearings, which is suitable for carrying axial loads, and its model numbers usually begin with “5”.
Thrust ball bearing is composed of a shaft ring, a seat ring, steel balls, and a cage assembly. Thrust ball bearings are suitable for loading unidirectional or bidirectional axial loads, but cannot bear radial loads. Common types include unidirectional thrust ball bearings (series 51) and bidirectional thrust ball bearings (series 52).
"5": The 51106 bearing type is thrust ball bearing
"11": The 51106 bearing size series is the “11” series
"06": The 51106 bearing inner diameter is 30mm (06×5=30mm)
"5": The 52210 bearing type is thrust ball bearing
"22": The 52210 bearing size series is “22” series
"10": The 52210 bearing inner diameter is 50mm (10×5=50mm)
(1) Thrust ball bearings must be mounted in an axially fixed position, avoiding tilting, in order to ensure normal force.
(2) Due to structural limitations, thrust ball bearings have a low limiting speed and are not suitable for high-speed applications.
Cylindrical roller bearing is one of the bearings suitable for high radial loads, and its model numbers usually start with “N”, including NU, NJ, N, NUP, etc. The bearings are available in a wide range of sizes and designs.
Cylindrical roller bearings have cylindrical rollers as rolling elements, and their structure adopts linear contact between rollers and raceways, which has a high radial load carrying capacity and is suitable for high loads and high-speed applications.
"NU": The NU312 bearing type is cylindrical roller bearing
"3": The NU312 bearing size series is the “3” series
"12": The NU312 bearing inner diameter is 60mm (12×5=60mm)
"NJ": The NJ310 bearing type is cylindrical roller bearing
"3": The NJ310 bearing size series is “3” series.
"10": The NJ310 bearing inner diameter is 50mm (10×5=50mm)
(1) Cylindrical roller bearings of type NU and N allow the shaft to move freely within a certain range and are suitable for free end support.
(2) Cylindrical roller bearings of type NUP with a single retaining edge and a stop ring can withstand bi-directional axial forces and are used at the fixed end.
(3) Cylindrical roller bearings of type NJ can be axially oriented in one direction and are subjected to a certain degree of unidirectional axial loads.
Tapered roller bearing is one of the bearings suitable for carrying compound loads, and its model numbers usually begin with “3”.
Tapered roller bearings have tapered rollers as rolling elements, and can support radial and unidirectional axial loads simultaneously. They are usually mounted in pairs to support bidirectional axial loads.
"3": The 32208 bearing type is tapered roller bearing
"22": The 32208 bearing size series is “22” series
"08": The 32208 bearing inner diameter is 40mm (08×5=40mm)
"3": The 30205 bearing type is tapered roller bearing
"02": The 30205 bearing size series is “02” series
"05": The inner diameter of the 30205 bearing is 25mm (05×5=25mm)
(1) Tapered roller bearings are generally mounted back-to-back (DB) or face-to-face (DF) to balance the axial force.
(2) Tapered roller bearings usually require adjustment of bearing clearance or preload during mounting to ensure stable operation.
Needle roller bearing is used in applications with high radial loads and restricted space, and its model numbers usually begin with “NK, NA, NKI, RNA, etc."
Needle roller bearings have long, thin rollers and have a high radial load carrying capacity while occupying less axial space. Types include those without an inner ring (RNA, NK types) and those with an inner ring (NA, NKI types).
"HK": The HK0810 bearing type is drawn cup needle roller bearing
"08": The HK0810 bearing inner diameter is 8mm
"10": The HK0810 bearing width is 10mm
"NK": The NK45/30 bearing type is needle roller bearing without inner ring
"45": The NK45/30 bearing inner diameter is 45mm
"30": The NK45/30 bearing width is 30mm
(1) Needle roller bearings are designed to withstand high radial loads but almost no axial loads.
(2) The diameter and length of needle roller bearings need to be selected according to the load calculation, and overloading will lead to early fatigue failure.
(3) Needle roller bearing mounting and fit is also key, interference fit may lead to deformation, clearance fit may be loose.
(4) Needle roller bearing types and sizes are varied and complex, selection needs to be comprehensive working conditions to choose the right bearing.
Spherical roller bearing is one of the bearings suitable for heavy loads and alignment requirements, and its model numbers usually begin with “2”.
Spherical roller bearings have a double-row roller structure and spherical raceways on the outer ring, which can be self-aligning and are suitable for alignment problems caused by mounting errors or shaft deflection, and can also withstand large radial and axial loads.
"2": The 22222 bearing type is spherical roller bearing
"22": The 22222 bearing size series is the “22” series.
"22": The 22222 bearing inner diameter is 110mm (22×5=110mm)
"2": The 22216 bearing type is spherical roller bearing
"22": The 22216 bearing size series is “22”.
"03": The 22216 bearing inner diameter is 80mm (16×5=80mm)
(1) Spherical roller bearings have the function of centering, generally can be centered 1 ° ~ 2.5 °, applicable to the housing rigidity of the working conditions.
(2) Tapered hole (K) spherical roller bearings can be fixed by the tight sleeve (H series) or retreat sleeve, suitable for large shaft diameter occasions.
Thrust cylindrical roller bearing is one of the bearings suitable for carrying unidirectional axial loads and has high rigidity, and its model number usually starts with “8”.
Cylindrical roller thrust bearings consist of a shaft ring, a seat ring and a roller cage assembly with cylindrical rollers, which provide high axial load carrying capacity and rigidity, but cannot carry radial loads.
"8": The 81108 bearing type is thrust cylindrical roller bearing
"11": The 81108 bearing size series is “11” series.
"08": The 81108 bearing inner diameter is 40mm (08×5=40mm)
"8"：The 81210 bearing type is thrust cylindrical roller bearing
"12": The 81210 bearing size series is “12” series
"10": The 81210 bearing inner diameter is 50mm (10×5=50mm)
(1) Thrust cylindrical roller bearings can withstand high unidirectional axial loads, but cannot withstand radial loads, the installation should ensure that the load direction is correct.
(2) Thrust cylindrical roller bearings should be mounted on a high rigidity support structure and ensure that their working surfaces are parallel to avoid early failure due to localized overloading.
Generally speaking, bearings could be selected based on bearing size, load, speed, working environment, and conditions of mounting, among other aspects. The following steps and recommendations shall be considered:
(1) Mainly radial load: Deep groove ball bearings (type 6), cylindrical roller bearings (type N), etc.
(2) Mainly axial load: Thrust ball bearing (class 5), thrust cylindrical roller bearing (class 8), among others.
(3) Mainly combination load (radial + axial): Angular contact ball bearing (class 7), tapered roller bearing (class 3), and so on.
(4) Shock or heavy load: To favored roller bearings, such as cylindrical roller bearing (type N), tapered roller bearing (type 3), or spherical roller bearing(type 2), among others.
(1) High-speed operation: The low-friction bearings are preferred, such as deep groove ball bearings (type 6), angular contact ball bearings (type 7), cylindrical roller bearings (type N), and so on.
(2) Low-speed and heavy load: Recommended tapered roller bearings (type 3), spherical roller bearings (type 2), etc.
(1) High-temperature environment: Use high-temperature resistant bearings, such as ceramic bearings or high-temperature grease-coated bearings, etc.
(2) Damp or corrosive environment: Use stainless steel bearings, ceramic bearings or anti-corrosive coating bearings, etc.
(3) Dusty environment: For a generally polluted environment, use metal shielded bearings (suffix code ZZ); for a more serious polluted environment, use the bearing with rubber sealed (suffix code 2RS).
(1) According to the bearing size, it can be divided into miniature bearings, medium-sized bearings, large-sized bearings, super large-sized bearings, etc. In selecting bearings, the mounting space should be confirmed and the appropriate size selected.
(2) Confirm the selection of appropriate bearing precision grade (P0, P6, P5, etc.) and clearance grade (C1, C3, C4, etc.).
(3) Bearing and shaft, bearing housing with a reasonable amount of interference, to avoid too tight or too loose.
(4) Bearing mounting methods (press-in, heating, cold shrinkage) should conform to the requirement of specifications, in order not to cause damage to the raceway or the rolling body.
Many people select the bearing type only according to its inner diameter, outer diameter, and width. While ignoring the type of bearing load (radial, axial, and composite load). Neglecting the load direction may lead to early bearing failure.
(1) Understanding bearing speed is very important, not all bearings are suitable for high-speed environment. The speed of a bearing is related to the type, accuracy, and lubrication. (2) Bearing types suitable for high-speed applications, such as deep groove ball bearings (type 6), angular contact ball bearings (type 7) and cylindrical roller bearings (type N) and so on.
(3) For ordinary equipment, precision P0 and P6 are sufficient for use. But for high-speed and high-precision machinery and equipment, the precision level needs to use P5, P4 or even P2.
(4) Lubrication for the bearing speed also has an impact, grease lubrication is suitable for medium speed, oil lubrication is suitable for ultra-high speed.
The model naming rules of different brands and manufacturers are slightly different, and the models of the same bearings may be different. It is necessary to check the brand manual or consult the bearing manufacturer.
The suffix of the bearing indicates that it has different structure or other special characteristics from the basic design. Ignoring the suffix may affect the normal operation of the bearing.
(1) For example, ZZ and 2RS are bearings with different seals, which are suitable for different application scenarios. Open bearings are suitable for clean and high speed environments, ZZ (metal seal cover) is suitable for general pollution environments, and 2RS (rubber seal cover) is suitable for more polluted environments.
(2) P0, P4, P5 belongs to the precision grade of the bearing, the precision grade is very important to the speed of the bearing and the use of the environment. However, it is not the higher the precision the better, for example, P4 grade bearings are used in ordinary scenes, the cost increases but there is no real benefit.
(3) C1, C3 and so on belong to the clearance level of the bearing, if the clearance of “C3” is wrongly used in ordinary scenes, it may lead to noise increase.
Bearing installation requires the use of correct installation tools and methods, not violent installation, or may damage the bearing raceway. In addition, after mounting, the bearings need to be inspected and maintained regularly to prevent early failure.
