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Miniature & Small ball bearings -Handling of a Bearing

If ball bearings were improperly assembled to either shafts or housings, the bearings could be damaged. This would shorten the life due to noise, vibration, and heat generation. Careful handling is also required during shipping and storing. If glue needs to be used, please use it with a full understanding of its characteristics.

Handling of a ball bearing

Ball bearings favor clean environments as they are very precise mechanical parts. Please maintain clean environments for their usage.

Assembling of a ball bearing

There are many methods to assemble the bearings to either shafts or housings. The followings are important for the assembly process.
When bearings are assembled to either shafts or housings by any fit methods, their centers must be on the same line, and assembled at right angles. (Figure 19-1) If interference fit is the case, the pressing force has to be applied to either the inner ring or outer ring at a right angle. Please apply the load slowly instead of applying a strong impact using tools like a hammer.
Brinelling could occur on the inner surface of bearing components when moment loads are applied to inner rings and outer rings in the moment clearance direction, and press fitted with wrong load positions. If the bearings are sealed or shielded, please avoid applying loads on them.

Handling of shafts and housings

If shafts and housings are contaminated, some problems with improper bearing installation may occur. Misalignment happens if the contaminated or damaged shafts and housings are assembled to the bearings. Shafts and housings will be damaged if they are press fitted with misalignment.
Since the inner and outer rings of ball bearings are very thin, raceways of inner and outer rings will be affected easily by the shapes of shafts and housings when they are assembled with interference fits. Inner and outer rings could be deformed easily, especially when shaft or housing roundness is poor, and brinells or damage may occur. Noise will be louder, and life will be shortened as a result.

Shipping and storing after assembly

Even after assembly, bearings in motors with long shafts may become damaged.
If the bearings receive a strong impact through loads applied to the shaft, brinells could be made on the internal surfaces of the bearings. Vibrations can sometimes cause fretting, as well.

Assembling with glue

If glue is used for assembly, please note the following items.
If rust preventative oils applied on the outer surfaces of ball bearings need to be wiped away, please use clean cloths with alcohol absorbed. However, please avoid using excessive amounts of alcohol as it could migrate into the bearing along with contamination.
Common glues are as follows. Please select these glues once their characteristics are confirmed by contacting the glue manufacturer.

  1. liquid type
    Anaerobic, heat hardening, UV and visible light hardening types
  2. liquid combined type
    Room temperature hardening, heat hardening types

The amount of glue used for the assemblies should be minimized in order to prevent glue from migrating inside the bearings. If the adhesives migrate inside the bearings, some issues related to adhesives develop gradually as time goes by, especially when anaerobic, UV and visible light type adhesives are used. Please use only the necessary amounts as shown in figure 19-4. A groove for the glue is also effective.
Please avoid exposing the bearings to high temperature during the hardening process. Lower temperature is favorable for hardening. If the UV lights some portions of the grease in the UV lighting device, some greases will increase in temperature. Long, excessive exposure to the light needs to be avoided. Grease degrades and leaks when exposed to high temperatures for a long time.
Cyanoacrylate adhesive (instant adhesive) could cause whitening of grease, and interrupt smooth rotation due to the gas generated during the hardening reaction.

Figure 19-1 handling during insertion

Figure 19-2 load position for press fit

Figure 19-3 misalignment due to contamination and damage

Figure 19-4 applying glue (examples)

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Home ... Engineering Information... Miniature & Small ball bearings... Handling of a Bearing