Applying adhesive:
The following lists good manufacturing practices for using adhesive
to bond small bearings.
- Clean mating surfaces - surfaces must
be cleaned and free from grease or oils. Since bearings will
have been lubricated, it is particularly important to clean
the outer surfaces of the races. In some cases, bearings are
available pre-cleaned by the manufacturer.
- Use primer if necessary - anaerobic adhesives
require at least one mating surface
to have some porosity to oxygen. If coated or anodized materials
are used, then a suitable primer will be necessary. The use
of a primer may also improve bond strength when dissimilar materials
are used in bearings and mating components. See adhesive manufacturers
specifications on primer use.
- Control the amount of adhesive applied -
if possible, use an electronic dispenser that delivers an accurately
controlled amount of adhesive. This amount should be set to
minimize excess adhesive outside the adhesive groove(s). Distribute
the adhesive evenly around the circumference of the part.
- Set-up time - a bonded assembly needs to
be left undisturbed for enough time that the adhesive sets up
sufficiently to retain the components in place. This period
is specified by the adhesive manufacturer and is different from
the time to achieve full cure.
- Remove excess adhesive - anaerobic
adhesive sets in the absence of air. Any excess adhesive left
on the outside of the mating surfaces will not set properly
and represents a hazard to the bearing as it may migrate into
the raceways, causing damage. All visible excess adhesive should
be wiped off after the part has set-up. Alternatively, an ultraviolet
curing adhesive can be used, where exposure to a strong UV source
after set-up will cure any remaining adhesive.
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