Bearing Selection These Factors Should Pay Special Attention To

Bearing selection needs to consider these factors, let's take a look.

"All types of bearings have different characteristics due to their different designs. Due to the variability and complexity of the specific installation position and application of bearings, there is no fixed mode for the selection of bearing types to adapt to the specific installation position and application conditions of a certain host, it is recommended to consider the following main factors comprehensively."

Allow space

Mechanical design, generally determine the size of the shaft, and then select bearings according to the size of the shaft. Usually, the small shaft selection of ball bearings; Large shaft selection of cylindrical roller bearings, self-aligning roller bearings, tapered roller bearings (sometimes also can choose ball bearings). If the radial space of the bearing installation part is limited, the bearing with smaller radial section height should be used. Such as needle roller bearings, some series of deep groove ball bearings, angular contact ball bearings, cylindrical or self-aligning roller bearings and thin wall bearings. If the axial space of the bearing installation part is limited, smaller width size bearings can be used.

Bearing load

Load size Load size is usually the determining factor in the selection of bearing size. Roller bearings have greater bearing capacity than ball bearings with the same dimensions. Usually ball bearings are suitable for light or medium loads, roller bearings are suitable for bearing heavy loads.

Pure radial load can use deep groove ball bearings, cylindrical roller bearings. Pure axial load can choose thrust ball bearing, thrust cylindrical roller bearing. When there is radial load and axial load (combined load), angular contact ball bearings or tapered roller bearings are generally used. If the radial load is large and the axial load is small, the bearings are professional in wechat! Deep groove ball bearings and cylindrical roller bearings with inner and outer rings can be selected. If there is also large deformation of shaft or shell and poor installation of neutral, self-aligning ball bearings and self-aligning roller bearings can be selected. If the axial load is large and the radial load is small, thrust angular contact ball bearings can be selected. If the self-aligning performance of four-point contact ball bearings is also required, thrust self-aligning roller bearings can be selected.

speed

The working speed of rolling bearings mainly depends on its allowable operating temperature. Bearings with low friction resistance and less internal heat are suitable for high-speed operation. When only bearing radial load, using deep groove ball bearings and cylindrical roller bearings can achieve higher speed, if bearing combined load, should choose angular contact ball bearings. Specially designed high-precision angular contact ball bearings can achieve extremely high speed. The speed of all kinds of thrust bearings is lower than that of radial bearings.

Rotation accuracy

For the majority of machinery, choose a level 0 tolerance of bearing is enough to meet the requirements of the host, but on the axis of rotation accuracy have strict requirements, such as spindle, precision machinery and instrument etc., should choose high tolerance grade of deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings and thrust angular contact ball bearings.

rigid

The rigidity of a rolling bearing is determined by the amount of elastic deformation that occurs when it is under load. In general, such deformation is small and can be ignored, but in some machinery, such as machine tool spindle system, the static stiffness and dynamic stiffness of the bearing have a great influence on the characteristics of the system. Bearing people wechat professional! Generally speaking, roller bearings have higher stiffness than ball bearings. Various types of bearings can also improve rigidity to varying degrees by properly "pretightening".

Noise and vibration

The noise and vibration of the bearing itself are generally very low. But for small and medium-sized motors, office machinery, household appliances and instruments, which have special requirements on noise and running stability, low-noise bearings are usually selected.

The axial moving

The most common way to configure bearings is to install a set of axially positioned "fixed bearings" at one end of the shaft, and install a set of axially movable "moving bearings" at the other end, in order to prevent the phenomenon of stuck due to thermal expansion and contraction of the shaft. The "moving bearings" often used are cylindrical roller bearings with inner or outer rings without retaining edges. Interference fit can be used when the inner ring and shaft are matched or the outer ring and shell hole are matched. Sometimes non-separable deep groove ball bearings or self-aligning roller bearings can also be used as moving bearings, but in the installation of the inner ring and the shaft or the outer ring and the shell hole should choose the clearance match, to ensure that the inner ring or outer ring has enough freedom of axial movement.

Friction torque

The friction resistance of ball bearing is smaller than that of roller bearing, and the friction resistance of radial contact bearing is smaller under pure radial load. When pure axial load is applied, the friction resistance of axial contact bearing is small. When combined load is applied, the friction resistance of angular contact bearing with similar load Angle is the least. In the need of low friction torque in the instrument and machinery, the choice of ball bearings or cylindrical roller bearings is more appropriate. Bearing people wechat professional! In addition, contact seals should be avoided for low friction torque bearings, and it is recommended to use drop oil lubrication, oil-gas lubrication or other lubrication methods conducive to reducing wear.

Installation and disassembly

Bearings with cylindrical inner holes are used in machinery with frequent installation and disassembly. Separated angular contact ball bearings, tapered roller bearings, separable cylindrical roller bearings, needle roller bearings and thrust bearings should be preferentially selected. Bearings with conical inner holes can be mounted on the journal, or on the cylindrical journal with the help of a set sleeve or unloader suit for easy installation and disassembly.