2018-07-20

Bearing models generally have a front code, a basic code and a post code. In general, the bearing model is only indicated by the basic model. The basic model generally consists of three parts, type code, size code and inner diameter code. The post code is a letter, a number, etc., indicating the structure, tolerances, and special requirements of the bearing. The pre-code is used to indicate the sub-parts of the bearing and is represented by letters.

General bearing (rolling bearing) code method

Divided into: pre-code, basic code and post code.

**1. Basic code**

(Type code, size code, ID code [2 digits]) The basic code is used to indicate the inner diameter, diameter series, width series and type of the bearing, generally up to five digits, first described as follows:

1) The inner diameter of the bearing is indicated by the first digit from the right of the basic code. For a common inner diameter d = 20 ~ 480mm bearing inner diameter is generally a multiple of 5, these two digits represent the quotient of the bearing inner diameter size divided by 5, such as 04 for d = 20mm; 12 for d = 60mm and so on. For bearings with inner diameters of 10 mm, 12 mm, 15 mm, and 17 mm, the inner diameter codes are 00, 01, 02, and 03 in order. For bearings with an inner diameter of less than 10 mm and greater than 500 mm, the inner diameter representation method is otherwise specified, see GB/T272-93.

2) The diameter series of the bearing (that is, the series of changes in outer diameter and width of bearings with the same structure and the same inner diameter) is represented by the third digit from the right of the basic code. For example, for a radial bearing and a radial thrust bearing, 0, 1 denotes an extra light series; 2 denotes a light series; 3 denotes a middle series; 4 denotes a heavy series. The size comparison between the series is shown in the figure below. The thrust bearing is identical to the representation of the radial bearing except that the 1 indicates the extra-light series.

3) The width series of the bearing (that is, the series of changes in the bearing width of the same structure, inner diameter and diameter series) is represented by the fourth digit from the right of the basic code. When the comparison of the width series of the 13-4 diameter series is 0 series (normal series), the width series code O may not be marked for most bearings in the code, but for the spherical roller bearing and the tapered roller bearing, the width series Code 0 should be marked. Diameter series code and width series code are collectively referred to as size series code.

4) The bearing type code is represented by the fifth digit from the right of the basic code (for the type of cylindrical roller bearing and needle bearing, the letter is the letter).

**2. Post code**

The rear code of the bearing is a letter, a number, etc., indicating the structure, tolerances, and special requirements of the bearing. There are many contents of the post code. Here are a few common codes.

1) The internal structure code indicates the different internal structure of the same type of bearing, which is indicated by the letter followed by the basic code. For example, angular contact ball bearings with contact angles of 15°, 25° and 40° use C, AC and B to indicate the difference in internal structure.

2) The tolerance class of the bearing is divided into 2, 4, 5, 6, 6X and 0, a total of 6 levels, from high to low, the codes are /PZ, /P4, /PS, /P6, /P6X and /PO. In the tolerance class, the 6X grade is only applicable to tapered roller bearings; the 0 grade is normal grade, and is not marked in the bearing code.

3) The commonly used radial clearance series of bearings is divided into 1 group, 2 groups, 0 groups, 3 groups, 4 groups and 5 groups, with 6 groups in total, and the radial clearance is from small to large. o Group clearance is a commonly used clearance group, which is not marked in the bearing code. The remaining clearance groups are represented by /CI, /CZ, /C3, /C4, /CS in the bearing code.

**3. Preamble code**

The front code of the bearing is used to indicate the sub-parts of the bearing, which are indicated by letters. For example, L denotes a separable ferrule of a separable bearing; K denotes a rolling element and a cage assembly of the bearing, and the like. There are many types of rolling bearings for practical applications, and the corresponding bearing codes are also complicated. The code number introduced above is the most basic and most commonly used part of the bearing code. If you are familiar with this part code, you can identify and select the commonly used bearings. The detailed code method for rolling bearings can be found in GBT272-93.

Bearing type, the size of the bearing can be judged intuitively from the model.

Type code, intuitively from the bearing can determine the type of bearing structure (mainly according to the shape of the rolling body).

The outer diameter code can only determine the series from the bearing model, and what series and what size. ISO and bearing major producing countries have standards, and countries basically follow ISO standards. Specific parameters need to consult the manual. The width code is basically the same as the series code of the outer diameter. You need to consult the manual.

Inner diameter code:

The basic bearing code is: three numbers, four numbers, five numbers, and slashes.

The three numbers consist of: from right to left, the first number indicates the size of the inner warp, and the number is a few inner diameters or a few mm. For example: the inner diameter of the 608 bearing is 8mm.

Four numbers and five numbers: from right to left, the first two numbers are the inner diameter code. Where: 00 indicates that the inner diameter of the bearing is 10 mm, 01 indicates that the inner diameter of the bearing is 12 mm, 02 indicates that the inner diameter of the bearing is 15 mm, and 03 indicates that the inner diameter of the bearing is 17 mm. 04 or above (including 04) The inner diameter is equal to the number from the right to the left, and the first two digits are multiplied by five. For example: the inner diameter of the 6201 is: 12mm. The bearing inner diameter of the 6204 is 20mm.

The bearing model has a slash inside, and the number on the right side of the slash is the size of the inner diameter. For example: NK20/16 has an inner diameter of 16mm. The inner diameter of the 230/500 bearing is 500mm.

The calculation method for the inner diameter code and inner diameter of the metric rolling bearing is basically the same.

Inch bearings and some individual factory representation methods have other methods.

Outer diameter code resolution:

Example: 6205

05 denotes the inner diameter code. Inner diameter size (mm) = 05 times 5 = 25mm

2 indicates the diameter series code. Bearings with the same internal diameter series code, the diameter series code indicates the size of the outer diameter of the bearing. The inner diameter is the same, the outer diameter is 4>3>2>0>9>8>7 (some manufacturers have 7 series, some are not), that is to say 6405, 6305, 6205, 6005, 6905 (61905), 6805 (61805) , 6705, these bearings are deep groove ball bearings with the same inner diameter and smaller outer diameter.

Width code:

The bearing number is the fourth number from right to left and is the width code. Example: 21315 is the width of the "1" series. 6205 is the "0" series width (actually 6 (0) 205, width "0" is omitted. “0” “1” “2” “3” “4” “5” “6”. . . . . . . . . . In the case of the same inner diameter and the same outer diameter, the width dimension is sequentially widened.

Type code

Add the first or first and second numbers from left to right

"6" means deep groove ball bearing

"4" means double row deep groove ball bearings

“2” or “1” means self-aligning ball bearing (basic model total of four digits 0: indicating double row self-aligning ball bearing

Example: 2205 1204

The standard model should be 02205, 0 is omitted.

The standard model number should be 01204, 0 is omitted. )

"21", "22", "23" and "24" indicate spherical roller bearings.

“N” means cylindrical roller bearings (including short cylindrical rollers and a part of elongated needles)

"7" means angular contact ball bearing

"3" means tapered roller bearing (metric)

"51", "52" and "53" indicate centripetal thrust ball bearings (five figures for basic models)

"81" indicates thrust short cylindrical roller bearing

"29" indicates thrust spherical roller bearing

Everyone has a different understanding. The content I write is not authoritative. I only think that the bearing concept is clear, convenient and practical.

**Basic type code of common bearings**

Bearing type | Code | Bearing type | 代号 |

Self-aligning ball bearing | 1 | Angular contact ball bearings | 7 |

Self-aligning tweezers bearing | 2 | Thrust tweezers | 8 |

Tapered tweezers | 3 | Thrust cone tweezers | 9 |

Double row deep groove ball bearing | 4 | Cylindrical tweezers bearing (outer ring without ribs) | N |

Cylindrical tweezers bearing (without ribs on the inner ring) | NU | Cylindrical tweezers bearing (single ring single rib) | NJ |

Cylindrical tweezers bearing (single rib with inner ring and flat ring) | NUP | Cylindrical tweezers bearing (outer ring single rib) | NF |

Cylindrical tweezers bearing (double row) | NN | Cylindrical tweezers bearing (with no ribs in the inner ring) | NNU |

Thrust ball bearing | 5 | Needle bearing | NA |

Needle roller bearing (punched punched outer ring) | HK | Needle roller bearing (sealing type drawn outer ring) | BK |

Needle roller and cage assembly | K | Thrust needle roller and cage assembly | AXK |

Deep groove ball bearing | 6 | Spherical ball bearing | U |

Four point contact ball bearing | QJ | Radial insert ball bearing (with top wire) | UC |

Spherical ball bearings (with eccentric sleeve) | UEL | Spherical ball bearing (conical hole) | UK |

**Pre-code:**

Separable inner or outer ring of separable bearing | L（LNU207） | Bearings without separable inner or outer rings (needle bearings are only available for NA type) | R（RNU207） |

Roller and cage assembly | K（K81107） | Thrust cylindrical roller bearing collar | WS（WS81107） |

Thrust cylindrical roller bearing race | GS（GS81107） |

**Post code and meaning (internal structure code):**

meaning | Code |

Indicates internal structural changes Represents a standard design, the meaning of which varies by type and structure | A、B、C、D、E |

1. Angular contact ball bearing Nominal contact angle 40 degrees | B |

Angular contact ball bearing nominal contact angle 15 degrees Spherical roller bearing type C | C |

Enhanced | E |

Angular contact ball bearing nominal contact angle 25 degrees
| AC |

Split bearing | D（K50*55*20D） |

Needle cage assembly double row | ZW（K20*25*40ZW） |

**Post code and meaning (sealing, dustproof and external shape change code)**

meaning | Code |

Tapered bore bearing, taper 1:12 (excluding outer spherical bearings) | K（1210K） |

Tapered bore bearing Taper 1:30 | K30（24122 K30） |

The outer ring of the bearing has a stop rib (flange outer ring) (not suitable for radial ball bearings with an inner diameter of less than 10mm) | R |

There is a stop groove on the outer ring of the bearing | N |

The outer ring of the bearing has a retaining groove with a snap ring | NR |

One side bearing bearing with skeleton oil seal (contact type) | -RS |

Skeleton oil seal on both sides of the bearing (contact type) | -2RS |

One side bearing bearing with skeleton oil seal (non-contact type) | -RZ |

Bearing oil seal on both sides of the bearing (non-contact) | -2RZ |

Bearing with dust cover on one side | -Z |

Bearing with dust cover on both sides | -2Z |

The bearing has a skeleton oil seal (contact type) on one side and a dust cover on one side | -RSZ |

The bearing has a skeleton oil seal on one side (non-contact type) and a dust cover on one side | -RZZ |

The bearing has a dust cover on one side and a stop groove on the outer ring on the other side. | -ZN |

The bearing has a dust cover on one side and a snap groove on the outer ring with a snap ring | -ZNR |

The bearing has a dust cover on one side and a stop groove on the same outer ring | -ZNB |

The bearing has a dust cover on both sides and a snap groove on the outer ring | -2ZN |

Thrust ball bearing with spherical washer | U |

**Inner diameter code:**

Bearing number or inner diameter | Inner diameter code | Example |

3 numbers | From right to left, the first number indicates the size of the inner warp, and the number is a few inner diameters or a few mm. | 608, inner diameter 8mm |

4 numbers and 5 numbers; 20 to 480 (except 22, 28, 32) | Number two digits after the number is multiplied by 5 | 33205, inner diameter 25 |

4 and 5 numbers with an internal diameter of 10 to 17 mm | Number two after the number 00 | 10mm |

Number two after the 01 | 12mm | |

Number two after the number 02 | 15mm | |

Number two after the number 03 | 17mm | |

Internal diameter greater than and equal to 500 and 22, 28, 32 | Directly expressed in millimeters of inner diameter, but separated by "/" between the series of dimensions | 62/22 |