Selection of a suitable standard bearing - or the decision to use a non-standard bearing - must take performance requirements and operating limitations into consideration. This may involve conflicts which must be resolved to reach a practical solution. Each performance requirement, such as speed, torque or load rating, usually generates its own specifications which can be compared with available bearing characteristics. If a standard bearing does not meet the requirements, a design compromise will be necessary in either the assembly or the bearing. At this point, the creation of a special bearing should be explored.
Among the most important application considerations which need to be evaluated are speed and load conditions. Specific bearing design choices should be based on anticipated operating conditions. Design choices include:
- Materials (balls and rings - hybrid bearings)
- Bearing type
- Bearing size and capacity
- Internal design perameters
- Preloading (duplexing)
- Tolerances and geometric accuracy
Barden precision bearings are available in two basic design configurations: deep groove and angular contact. Selection between these configurations primarily depends on application characteristics such as:
- Magnitude and direction of loading
- Operating speed and conditions
- Requirements for accuracy and rigidity
- Need for built-in sealing or shielding
Barden bearings are sized in both inch and metric dimensions and overall, bearings can range from 4mm (0.16") to 180mm (approx 7") OD. Criteria influencing size selection includes:
- Mating parts ... bearing dimensions may be governed by the size of a mating part, eg. shaft or housing.
- Capacity ... bearing loading, dynamic and static, will establish minimum capacity requirements and influence size selection because capacity generally increases with size. Full complement bearings can offer a solution here.
- Attainable speeds ... smaller bearings can usually operate at higher speeds than larger bearings, hence the speed requirement of an application may affect size selection.
- Stiffness ... large bearings yield less than small bearings and are the better choice where bearing stiffness is crucial.
- Weight ... in some cases bearing weight may have to be factored into the selection process.
- Torque ... reducing the ball size and using wider raceway curvatures are tactics which may be used to reduce torque.
- Diameter series ... for spindle and turbine size bearings, most bore diameter sizes have several progressively increasing series of outside diameters, width and ball size, termed Series 1900, 100, 200 and 300.
Ball and Ring Materials
Selection of a material for bearing rings and balls is strongly influenced by availability. Standard bearing materials have been established and are the most likely to be available without delay. For special materials, availability should be determined and these additional factors considered during the selection process:
- Material cleanliness
- Fatigue resistance
- Dimensional stability
- Corrosion resistance
- Wear resistance
- Temperature resistance
For all ball and ring materials, Barden has established specifications which meet or exceed industry standards. Before any material is used in production, mill samples are analysed and approved. The four predominant ring materials used by Barden are AISI 440C, SAE 52100, AISI M50 and Cronidur 30®. Ceramic balls can also be used as an alternative to traditional steel balls as part of a hybrid bearing.