+86-18615202650 Bearing Designation Codes Explained: How to Read Every Prefix, Suffix and Number in a Bearing Model
When you type a bearing model into Google you want one thing—immediate clarity. This guide gives it. Below you will learn the global language of rolling-bearing designation, discover why each letter and digit matters, and see real-world examples that turn mysterious codes into plain English. Every sub-heading contains the word bearing so search engines and humans alike know exactly what is covered.
- What a Bearing Code Is and Why It Exists
A bearing code is a short, standardized sentence that describes geometry, clearance, accuracy, sealing, material and more. ISO 15, DIN 620 and ABMA standards all use the same logic: fewer words, more data. Once you can read the sentence you can:
- Buy the correct replacement without seeing the old part
- Upgrade load rating or speed with a single suffix swap
- Avoid costly machine downtime caused by mis-ordered parts
- The Three-Part Blueprint of Every Bearing Number
Every rolling-bearing model is built from three ordered blocks:
Basic designation | Prefix set | Suffix set
Example: NU 2208 ECP
Example: NU 2208 ECP
- Basic designation tells type and size
- Prefixes describe unique designs or assemblies
- Suffixes add variants like seals, clearance, accuracy, material
Memorize the order and you can skim any catalog page in seconds.
- Basic Bearing Type Codes—The First Letter or Figure
The opening letter, or sometimes a leading digit, shouts the bearing family:
- 6 Deep-groove ball bearing
- 2 Self-aligning ball bearing
- 3 Tapered roller bearing
- 7 Angular-contact ball bearing
- NU Cylindrical roller, inner ring separable
- NJ Cylindrical roller, inner ring with thrust collar
- NN Double-row cylindrical roller
- BK Drawn-cup needle roller, closed end
If there is no letter, the code starts with the dimension-series figures described next.
- Dimension Series Inside a Bearing Model
Immediately after the type identifier you will see two digits that look innocent but carry huge meaning:
- First digit = width series (B, C, D, T, etc.)
- Second digit = diameter series (outer race size)
For instance 2208 means:
- 22 Light-wide series
- 08 bore code 40 mm
By changing 22 to 23 you gain width and load capacity without touching the shaft.
- The Secret Bearing Bore Code: 00 to 99
Multiply the last two digits by five and you get the bore in millimetres—except for tiny bearings:
- 00 10 mm
- 01 12 mm
- 02 15 mm
- 03 17 mm
- 04 20 mm, then add five each step (08 = 40 mm, 20 = 100 mm)
For bores ≥ 500 mm the system switches to /500, /530, written right after the dimension series.
- Prefixes: When a Bearing Needs Extra Identity
Prefixes sit before the basic code and flag special assemblies or applications:
- K Cage with rolling elements, no rings
- HK Drawn-cup needle, open
- BK Drawn-cup needle, closed
- NA Solid-ring needle roller
- AXK Needle thrust assembly
- IR Inner ring only
Prefixes let you buy exactly the component you need instead of an entire unit.
- Common Bearing Suffixes You Meet Every Day
Suffixes appear after the basic number and can stack. Each position has a defined order:
- Seals/shields
- ZZ (iron shield both sides)
- 2RS1 (rubber seal both sides)
- 2RSH (rubber seal both sides, different lip geometry)
- Cage design
- J (pressed steel)
- M (machined brass)
- TN9 (glass-fibre reinforced polyamide)
- Radial clearance
- C1 smaller than C2
- CN normal (often omitted)
- C3 larger than CN
- C4 larger than C3
- C5 largest
- Accuracy grade
- P0 (ABEC-1) standard
- P6 (ABEC-3) tighter
- P5 (ABEC-5) high
- P4 (ABEC-7) super
- P2 (ABEC-9) ultra
- Heat treatment
- S1 stabilized to 200 °C
- S3 stabilized to 300 °C
Example: 6210-2Z/C3HT = deep-groove ball bearing, shields both sides, C3 clearance, stabilized for 200 °C.
- Real-World Bearing Decoding Examples
SKF 22218 EK/C3
- 222 Spherical roller bearing
- 18 bore 90 mm
- EK Tapered bore 1:12, steel cage
- C3 Radial clearance above normal
FAG 32014-X-XL-P5
- 320 Tapered roller, metric
- 14 bore 70 mm
- X Modified internal geometry
- XL X-life design, higher capacity
- P5 ISO tolerance class 5
NTN 6008LLBC3P5/L283Q
- 6008 Deep-groove ball bearing 40 mm bore
- LLB Non-contact rubber seal both sides
- C3 clearance
- P5 precision
- L283 quiet-running grease for electric motors
- How to Choose the Correct Bearing Variant Fast
- Identify the basic code on the worn part
- Note every prefix and suffix—even the tiny dot counts
- Ask: does the application need more clearance (C3), better sealing (2RS1), higher speed (polyamide cage), or higher accuracy (P5)?
- Search the full code plus the word “bearing” to surface exact equivalents from any brand
- Cross-reference with manufacturer PDF tables to confirm boundary dimensions
- Cross-Referencing Bearing Brands Without Mistakes
Brands share ISO boundary plans, but suffixes differ. A SKF 6304-2RSH equals:
- FAG 6304-2RSR
- NTN 6304LLU
- NSK 6304DDU
- NACHI 6304-2NSE
Use a free online interchange tool, yet always double-check the clearance and cage symbols—those are not standardized across factories.
- Frequently Asked Questions About Bearing Codes
Q: Can I swap C3 for CN clearance?
A: Only if the operating temperature is low and the fit is not tight. Interference fits and high speed usually demand C3.
A: Only if the operating temperature is low and the fit is not tight. Interference fits and high speed usually demand C3.
Q: Does P5 instead of P0 change the outer dimensions?
A: No. Accuracy grades tighten tolerances; they do not alter boundary size.
A: No. Accuracy grades tighten tolerances; they do not alter boundary size.
Q: Are stainless bearings coded differently?
A: Yes. Most makers add an “H” or “SS” in the suffix, or use a separate series starting with “S”.
A: Yes. Most makers add an “H” or “SS” in the suffix, or use a separate series starting with “S”.
- Final Checklist: Read Any Bearing Code in Ten Seconds
- Spot the type letter or leading digit
- Read the dimension series (two digits)
- Multiply the last two digits by five for bore
- Scan prefixes for assemblies
- Read suffixes left-to-right: seals → cage → clearance → accuracy → heat
Master these five steps and you will never again stare at a long string of letters and numbers wondering what it means. Type the full code into Google followed by the word bearing, order with confidence, and keep your machines running.
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