Installing high precision bearings must be performed very carefully.
Below are a few best practices & tips we suggest when installing your high precision bearings:
- Ultra-clean environment
- Dedicated & appropriate tools for bearing installation
- Proper technique
- Well-designed bearing arrangement and preload strategy
- Application specific tolerance and surface treatment
- Proper starting operation and break in procedure
Prevent Bearing Contamination
The leading cause of premature bearing failure is contamination.
A long bearing life if usually the result of a clean environment. A separate room with no machining, grinding or debris is recommended when installing your angular contact bearings.
Open the sealed bearing bag only right before installation.
Just one single human hair can contaminate a precision ball bearing and can decrease bearing life. Many facilities use clean room attire such as gloves, aprons, hair nets, etc. to prevent bearing contamination; we also recommend installing in this type of clean room environment.
Using Bearing Installation Tools
Using the right tools during an install will make sure the bearing races are not dimpled during installation.
If a bearing is pressed into the shaft or inside the housing, deformation (dimpling) can occur and will greatly decrease the bearing life and running characteristics.
Proper technique overlaps with the right tools.
Heating the inner race of the bearing using an induction heater can support installation efforts. With some applications, a heated bearing can slide directly onto a shaft without the use of other tools.
Please note: A bearing shouldn’t be heated above the lubrication limit, cage limit, seal limit, or potentially any associated material limits.
If an induction heater is not handy an arbor press is recommended because the press can be done in a single motion. Stopping and starting a press along the shaft can increase opportunities for errors.
Using a hammer is not recommended but if one must be used make sure it’s a dead blow hammer. In no way use the dead blow hammer directly against the bearing, an intermediary tool is required (similar to press tools above).
A ball peen or metal hammer can greatly increase the opportunity for precision bearing damage.
System Design and Preload
A proper design and assembly strategy is required for a long super precision bearing life. Some key aspects are:
- Proper preload strategy
- Bearing size
- Load capacities
- Duty cycles
Click here for examples of bearing arrangements. Also click here for various techniques of precision preload options.
Tolerancing and surface treatments can have a large effect on super precision bearing life, especially in high speed applications.
Centrifugal forces are a concern for inner race lift off at high speeds. For this reason, correction factors need to be made for both RPM and thermal effects on materials.
Generalities of a slight press on the inner race and slight gap on the outer race can often be made. Be cautious of being too general, this can open one up for an easily avoided issue. Please click here for more information on tolerancing and thermal effects on mating parts.
Break In Procedure for Angular Contact Bearings
A complete and thoughtful break in procedure can also be the difference between a short and long precision bearing life.
No matter what the lubricant, polishing effects occur during break in that improve the performance of the precision bearings. For this reason, a proper start up and break in procedure should not be underestimated even for oil lubricated bearings.
‘Grease Fling’ can cause a very short grease lubrication life for the bearing, just the same as running a spindle before the oil jets come on can also greatly reduce bearing life.
Read more about proper break in procedures.