What are the Tolerance Grades of Bearings?

● ISO standard tolerance level

China's rolling bearings adopt ISO standard tolerance grades, graded according to size tolerances and rotation accuracy. Centripetal bearings (except conical roller bearings) are divided into five grades: 0, 6, 5, 4 and 2, and their accuracy is from low to high in turn. Conical roller bearings are divided into five grades: 0, 6X, 5, 4 and 2, and their accuracy is from low to high in turn. Thrust bearings are divided into four grades: 0, 6, 5 and 4, and their accuracy is from low to high in turn.

● US Standard Tolerance Rating

All countries in the world basically adopt ISO standard tolerance levels, and only the tolerance level representation method in the United States is different from this.

1. Centripetal ball bearings are divided into ABEC1, 3, 5, 7 and 9, and centripetal roller bearings (except conical roller bearings) are divided into three grades: RBEC1, 3 and 5, but these tolerance grades are equivalent to ISO standards in all aspects. ABEC1 and RBEC1 are suitable for general-purpose bearings, and other grades of bearings are suitable for occasions with high accuracy requirements.

2. The metric conical roller bearings are divided into six grades: K, N, C, B, A and AA, K and N are called standard grades, and the others are precision grades.

3. British conical roller bearings are divided into six grades: 4, 2, 3, 0, 00 and 000, with tolerance grades from low to high in turn.

4. American instrument precision ball bearings are divided into 3P, 5P, 7P, 9P, 5T and 7T.

● Special tolerance grade of special bearings

For some special bearings, special tolerance grades are also stipulated, mainly:

1. Precision bearings SP and UP grades for machine tools, 4A and 2A grades.

Among them, the dimensional accuracy of the SP level is equivalent to level 5, and the rotation accuracy is equivalent to level 4, the size accuracy of the UP level is equivalent to level 4, and the rotation accuracy is higher than level 4. The dimensional accuracy of level 4A is equivalent to level 4, and the rotation accuracy is equivalent to level 2, the size accuracy of level 2A is special, and the rotation accuracy is equivalent to level 2.

2. The precision ball bearings of the instrument are divided into 5A and 4A levels, from low to high in turn.

● Linear motion rolling bearing tolerance grade

1. ISO standard tolerance grades are divided into seven grades: L9, L7, L7A, L6, L6A, L6J and L6JA. Different grades are suitable for linear moving ball bearings of different series and structures.

2. The circulating needle roller rail support is divided into four grades: G, E and D.C according to the tolerance of the installation height, and the tolerance level is from low to high in turn.

3. The needle roller and pacolding assembly are divided into two levels of 05 according to the tolerance of the needle roller in the component. The tolerance grades used by foreign bearing companies are different.

The author of this article is Shaanxi Gainhui Heavy Industries Co., Ltd., which is a professional bearing manufacturer and distributor in China. The company supplies many types of the bearings, such as drawn cup needle roller bearings, yoke type track rollers, etc. With high quality and competitive bearing products, we sincerely provide services to customers all over the world.

Contact us for more details:

E-mail: emily@gainhui.com

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