Currently, as bearing design has become diversified, their application range is being increasingly extended. In order to select the most suitable bearings for an application, it is necessary to onduct a comprehensive study on both bearings and the equipment in which the bearings will be installed, including operating conditions, the performance required of the bearings, specifications of the other components to be installed along with the bearings, marketability, and cost performance, etc.
In selecting bearings, since the shaft diameter is usually determined beforehand, the prospective bearing type is chosen based upon installation space, intended arrangement, and according to the bore diameter required.
In selecting bearings, since the shaft diameter is usually determined beforehand, the prospective bearing type is chosen based upon installation space, intended arrangement, and according to the bore diameter required.
Next, from the bearing specifications are determined the service life required when compared to that of the equipment in which it is used, along with a calculation of the actual service life from operational loads.
Internal specifications including bearing accuracy, internal clearance, cage, and lubricant are also selected, depending on the application.
For reference, general selection procedure and operating conditions are described in Fig. 2-1. There is no need to follow a specific order, since the goal is to select the right bearing to achieve optimum performance.
1. Bearing type, arrangement
Operating conditions to be considered
- Installation space
- Load magnitude, types and direction of application
- Rotational speed
- Running accuracy
- Rigidity
- Misalignment
- Mounting ease
- Bearing arrangement
- Noise characteristics, friction torque
- Marketability, cost performance
2. Bearing dimension
Operating conditions to be considered
- Specifications for installation
- Recommended service life
- Dynamic equivalent load
- Static equivalent load, safety coefficient
- Rotational speed
3. Tolerance class
Operating conditions to be considered
- Running accuracy (runout)
- Noise characteristics, friction torque
- Rotational speed
4. Fit and internal clearance
Operating conditions to be considered
- Load magnitude, types
- Operational temperature distribution
- Materials, size and tolerances of shaft and housing
- Fit
- Difference in temperature of inner and outer rings
- Rotational speed
- Preload
5. Cage type, material
Operating conditions to be considered
- Rotational speed
- Noise characteristics
6. Countermeasure for special environmental condition
Operating conditions to be considered
- Conditions of application site (abnormal temperature, sea water, vacuum, chemical solution, dust, gas, magnetism)
- Lubrication
7. Lubrication, lubricant, sealing device
Operating conditions to be considered
- Operating temperature
- Rotational speed
- Lubrication
- Lubricant
- Sealing device
