Complete Information on What's Bearing Codes Stand for 2019 [Easy]

 

Bearing plays an indispensable role in both industrial life and daily life. Therefore, what's bearing codes stand for is very important for people. Certainly, some people can't understand bearing codes clearly which causes many serious problems. For example, choose an unmatched bearing will not only wear out machines but also affect the service life of bearing. So this is a small bearing guide that summarizes the code classification of the bearing.

And when you read this article, there may be some bearing codes that you have not currently seen before, however, I believe that as long as you are engaged in mechanical work, you will definitely need it in the future.

Classification of bearings

Firstly, I would like to introduce the basic classification of bearing which some people are familiar with. There are numbers and English alphabets in bearing names, and below is the meaning of them.

"6" means deep groove ball bearing (class 0)
"4" means double row deep groove ball bearings (class 0)
“2” or “1” means self-aligning ball bearings (four numbers for basic models) (Class 1)
"21", "22", "23" and "24" indicate spherical roller bearings. (3 categories)

• "N" means cylindrical roller bearing (including short cylindrical roller and part of slender needle) (class 2)
• "NU" inner ring without flange
• "NJ" inner ring single flange
• "NF" outer ring single flange
• "N" outer ring without flange
• "NN" double row cylindrical roller with no flange on the outer ring
• "NNU" double row cylindrical roller, the inner ring has no flange, the roller length is at least 5 times the diameter size, called needle bearing (4 types)
• "NA" rotary cut outer ring needle roller bearing
• "NK" needle roller bearings with stamped housing
• “K” needle roller and cage assembly, no internal and external rings

"7" means angular contact ball bearings (Type 6)
"3" means tapered roller bearing (metric) (Type 7)
“51”, “52” and “53” indicate centripetal thrust ball bearings (five figures for basic models) (Type 8)
"81" indicates thrust short cylindrical roller bearings (Type 9)
"29" indicates thrust spherical roller bearings (Type 9)

National Standard of Bearing

Secondly，it turns to the national standard of bearing. That is to say, bearings' inner diameters, outer diameters, width, and other sizes are line with the national standard GB/T 273.1-2003, GB/T 273.2-1998, GB/T 273.3-1999 or other relevant standards. Below is a table of more details.

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Prefix of Bearing

Thirdly, many bearings have front codes which are English alphabets. They are placed before the bearing model number. Therefore following is the explanation of the front code.

The pre-code R is placed directly before the bearing basic code, and the rest of the code is separated from the basic code by a small dot.

GS.—— Thrust cylindrical roller bearing races. Example: GS.81112
K. - Assembly of rolling elements and cages. Example: Combination of thrust cylindrical roller and cage K.81108
R – Bearing without a separate inner or outer ring. Example: RNU207 - NU207 bearing without inner ring
WS - Thrust cylindrical roller bearing shaft ring. Example: WS.81112

Suffix Codes of Bearings

Finally is about the postcode of bearings. The postcode is placed behind the base code number. Some post-codes are separated from the base code by small dots. However, different postcodes have different meanings.

Suffix Codes- Internal Structure

A, B, C, D, E - the change of internal structure for example：
Example: Angular contact ball bearings 7205C, 7205E, 7205B, C-15° contact angle, E-25 ° antenna angle, B-40° contact angle
Example: Cylindrical roller, spherical roller and thrust spherical roller bearings N309E, 21309 E, 29412E - Reinforced design, improved bearing load capacity.
VH——Roller self-locking full-roller cylindrical roller bearing (the compound diameter of the roller which is different from the standard bearing of the same type) Example: NJ2312VH

Suffix Codes - Bearing Dimensions and External Structure

On the one hand, some postcodes stand for the bearing dimensions and their external structure so that people can classify bearing dimensions more quickly.

DA - Detachable double row angular contact ball bearings with double inner rings. For example 3306DA
DZ - Cylindrical roller bearing with outer diameter. Example: ST017DZ
K—— Tapered bore bearing with a taper of 1:12. Example: 2308K
K30- Tapered bore bearing, taper 1:30. Example: 24040 K30
2LS - Double row cylindrical roller bearings with dust caps on both sides of the double inner ring. Example: NNF5026VC.2LS.V - Internal structure change, double inner ring, dust cover on both sides, full roller double row cylindrical roller bearing

N——The bearing with the retaining groove on the outer ring. For example 6207N
NR - Bearing with snap groove and snap ring on the outer ring. For example 6207 NR
N2-—— Four-point contact ball bearing with two retaining grooves on the outer ring. For example QJ315N2
S—— Bearing with oil groove and three lubrication holes in the outer ring. For example, 23040 S. Spherical roller bearings with bearing outer diameter D ≥ 320mm are not marked S
X—— The dimensions are in accordance with international standards. Example: 32036X
Z••——Technical conditions for special structures. Arrange sequentially from Z11. Example: Z15 - Stainless Steel Bearing (W-N01.3541)

ZZ——Roller bearing with two retaining rings for guiding the outer ring

Suffix - Seals and Dustproof Covers

On the other hand, some postcodes mean bearing seals or covers. For instance, RS means rubber seals, below is more details.

RSR - The bearing has a seal on one side. Example: 6207 RSR
2RSR - Bearing seals on both sides. Example: 6207.2RSR
ZR - The bearing has a dust cover on one side. Example: 6207 ZR
2ZR- Bearings have dust caps on both sides. Example: 6207.2ZR
ZRN - The bearing has a dust cover on one side and a stop groove on the outer ring on the other side. Example: 6207 ZRN
2ZRN - The bearing has a dust cover on both sides and a snap groove on the outer ring. Example: 6207.2ZRN

In conclusion, the above is the classification of bearing prefix and suffix, understand what's bearing codes stand for is so significant. After reading this article, you will know more about bearing prefix and suffix, what's more, you can classify bearings easily. Bearings are so important to us, in other words, how to classify bearing according to bearing codes has become a hot topic for people to think about. Consequently, this article can definitely improve work efficiency. Moreover, we will continue to update.