Detailed description of rolling bearing precision grade and selection

Bearing is one of the commonly used parts in mechanical equipment, due to the different precision requirements of the equipment,
plus the bearing precision provided by different manufacturers are also different.But no matter how the requirements of the bearing precision,
for the bearing precision or there is a level of standard, in addition, the choice of the bearing is also a strict standard.Today xiaobian to tell you about the accuracy of rolling bearings and selection

The precision of bearing includes dimension precision and rotation precision.Dimensional accuracy is the required item for mounting a bearing on a shaft or bearing box. It includes inner diameter, outer diameter, width, chamfering dimensional tolerances or allowable values.
The geometric accuracy includes internal diameter deviation, average internal diameter difference, external diameter deviation, average external diameter difference and allowable value of the ring end face parallel difference.The precision of rotation is specified for the pendulum during rotation, including radial and axial swing of inner and outer rings, and vertical tolerance range of inner ring side swing and outer diameter surface.

One.Bearing accuracy class code

1.China bearing previous code accuracy class code
The standards developed by each country are based on ISO standards, which are generally related to ISO- and are individually stricter than ISO standard

The precision is divided into dimension precision and rotation precision,It is divided into level 0, level 6, level 6, level 5, level 4 and level 2
The old code standard of Chinese bearings before is :G class (0 class) E class (6 class) D class (5 class) C class (4 class) B class (2 class)。

2.Current code generally adopts German DIN standard
Accuracy level has been standardized and divided into P0 (0 level), P6 (6 level), P5 (5 level), P4 (4 level), P2 (2 level)

The precision of bearing is improved successively from level 0. PO level is a national standard, and it is also a common standard in the bearing industry, so it is also called ordinary level.
At present, most manufacturers in China also produce PO level products, while P2 level is a precision level, and specific technical parameters are also standardized

General standard grade P0, reflected in the bearing type is omitted, only P6 or above, the grade code appears in the bearing type

For example: 6205 and 6205/p5, where the precision level of 6205 is PO, but it is omitted, which gives people the impression that the PO level is non-precision level bearing

Two.The selection of bearings with different precision
1.Grade 0: in the rotation accuracy of more than 10 m of the general bearing system, it is widely used such as the common machine tool speed change mechanism feed mechanism automobile tractor speed change mechanism,
common motor water pump and agricultural machinery and other general machinery of the rotation mechanism

2, Grade 5: In precision bearing systems with rotation accuracy of 5-10 m or higher rotation speed, such as bearings used in ordinary lathes (5 for front support, 6 for rear support),
more precise instruments, instruments, and precise rotating mechanisms。

3 ,Grade 2: In ultra-precision instruments with rotation accuracy of less than 5 m or at very high speeds, such as precision jig boring machines, gear systems for precision grinding machines, precision instruments, meters and high-speed cameras.

A good bearing is important is used in the appropriate place, the bearings suitable place, there must be precision grade to divide.In mechanical equipment, it is impossible for a high precision bearing to replace the general bearings, general bearings can not replace the high precision class of bearings.