Basic knowledge of bearing identification by dimensions

Time：2020.03.24  Source：Roller Bearings Suppliers

The bearing model generally has a front code, a basic code and a post code. In general, the bearing type is only indicated by the basic type. The basic model generally consists of three parts, type code, size code and inner diameter code. The post code is used to indicate the structure, tolerances and special requirements of the material by letters and numbers. The front code is used to indicate the sub-components of the bearing, which are represented by letters.

Bearing identification by dimensions

General bearing (rolling bearing) designation method is divided into: front designation, basic designation and rear designation.

1. Basic code

(Type code, size code, inner diameter code [2 digits]) The basic code is used to indicate the inner diameter, diameter series, width series and type of the bearing. Generally, it has a maximum of five digits.

(1) The inner diameter of the bearing is indicated by the first digit from the right of the basic code. For bearings with a common inner diameter d = 20 ～ 480mm, the inner diameter of the bearing is usually a multiple of 5. These two digits represent the quotient of the inner diameter of the bearing divided by 5, such as 04 for d = 20mm; 12 for d = 60mm and so on. For bearings with inner diameters of 10mm, 12mm, 15mm and 17mm, the inner diameter codes are 00, 01, 02 and 03 in this order. For bearings with an inner diameter of less than 10mm and more than 500mm, the method of expressing the inner diameter is otherwise specified, see SL045005PP.

(2) The diameter series of bearings (that is, the series of changes in outer diameter and width of bearings with the same structure and the same inner diameter) is indicated by the third digit from the right of the basic code. For example, for radial bearings and radial thrust bearings, 0, 1 means extra light series; 2 means light series; 3 means medium series; 4 means heavy series. The size comparison between the series is shown below. Except for the super light series, the thrust bearing is the same as that of the radial bearing.

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

（4）The bearing type code is indicated by the fifth digit from the right of the basic code (for cylindrical roller bearings and needle roller bearings, the type codes are letters).

2. Postcode

The post code of the bearing is to use letters and numbers to indicate the bearing structure, tolerances and special requirements of materials, etc. There are a lot of postcodes. Here are some commonly used codes.

(1) The internal structure code indicates different internal structures of the same type of bearing, which is indicated by a 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 differences in internal structure.

(2) Bearing tolerance grades are divided into 2 grades, 4 grades, 5 grades, 6 grades, 6X grades, and 0 grades. There are a total of 6 grades, in order from high to low. , / P6, / P6X, and / PO. Among tolerance grades, grade 6X is only applicable to tapered roller bearings; grade 0 is ordinary grade and is not marked in the bearing code. .

(3) The commonly used bearing radial clearance series are divided into 1 group, 2 group, 0 group, 3 group, 4 group and 5 group, a total of 6 groups, and the radial clearance is from small to large in order. The clearance of group o 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． Leading code

The front code of the bearing is used to indicate the sub-components of the bearing, which are represented by letters. For example, L is the separable bearing ring of the separable bearing; K is the rolling element and cage assembly of the bearing and so on. There are many types of rolling bearings used in practice, and the corresponding bearing codes are also more complicated. The code introduced above is the most basic and commonly used part of the bearing code. Once you are familiar with this code, you can identify and check the commonly used bearings. Refer to SL045004PP for the code method of full complement needle roller bearing.