What factors should be considered when choosing a rolling bearing?

There are many types and forms of rolling bearings, with a wide range of sizes. To select the right bearing for a design, it’s necessary to conduct a comprehensive analysis considering various factors such as the mechanical operating conditions, performance requirements, surrounding specifications, as well as marketability and cost-effectiveness. Since the shaft diameter is typically determined first before selecting a bearing, the type of bearing should be initially determined based on the inner diameter of the bearing, taking into account the installation space and configuration. Next, compare the “required bearing life” with the “bearing life calculated based on load” to determine the correct size. After that, the precision grade, internal clearance, cage, lubricant, and other internal features of the bearing must be specified. The general steps for selection are as follows:

1. Determine the bearing type and configuration. (Consideration factors include: installation space; load size, direction, and nature; rotational speed; rotational accuracy; noise and frictional torque; rigidity; relative inclination between the inner and outer rings; ease of installation and disassembly; bearing arrangement; marketability and cost-effectiveness.)

2. Determine the bearing size. (Required bearing life; equivalent dynamic load; equivalent static load; rotational speed; main dimensions of the bearing; basic dynamic load rating; basic static load rating; allowable axial load.)

3. Determine the precision grade. (Rotational accuracy; noise and frictional torque; rotational speed; bearing precision.)

4. Select the fit and internal clearance. (Load size and nature; operating temperature; materials, dimensions, and precision of the shaft and housing; fit; temperature difference between the inner and outer rings; rotational speed; preload; bearing precision; internal clearance.)

5. Choose the cage material and type. (Rotational speed; noise.)

6. Address special environmental conditions. (Media conditions such as temperature, seawater, vacuum, chemicals, dust, gas, magnetic fields, etc.; special materials; special heat treatments; special surface treatments; lubricants.)

7. Select the lubrication method, lubricant, and sealing system. (Operating temperature; rotational speed; lubrication method; lubricant; sealing system; bearing limit speed; grease life.)

8. Determine the installation and disassembly methods and related dimensions.

9. Finalize the specifications for the bearing and its surrounding components. This will result in a bearing that meets the required performance specifications.