Hi I have a question which i failed to get around. There is an issue of bearings spinning in the gearbox. Initially loctite and hysol where applied and started spinning again. Now a mechanical system is used where by a small groove in the bearing outer race is machined to locate an external pin when boxed up. Can anyone explain the impact of machining a groove in the bearing will have on its life. Also any experience with Hysol and loctite in spinning outer races

Hello Mate,
the outer race should not spin. There must be a problem with the needed interference between bearing and housing. I am not sure for using glue, the best is to assemble with the right interference between housing and outer ring. Look for the cause of the loose outer race, if it is due to a dark or black corrosion on the bearing outer face, that is fretting corrosion, then it was not assembled with the white assembly paste to prevent corrosion. Perhaps you want to re mechanize the housing and find an oversize bearing, or insert a ring to create the right interference (ask your bearing supplier if they can help you with any of those supplies). Assemble all tight clearances with white assembly paste and write me if you cannot find these in your market.

Good comments above.

My two cents...

Machining a groove in the back of the outer ring - that is creating a stress riser and asking for trouble.

Any of the bearing manufacturer's websites will give you recommended fits between inner ring/shaft and outer ring / bearing. These dimensions need to be checked during bearing replacement (I'll bet yours is too large). For typical equipment rotating inner ring/stationary outer ring, it is generally an an interference fit between inner ring/shaft and a looser fit between outer ring/housing. Movement of inner ring on shaft is not acceptable. Some movement of outer ring within housing is expected and usually not a problem if the fits are correct. How much movement is too much is somewhat subjective... brown/black fretting all the way around the outer ring so you can barely see the original metal any more I guess would be too much.

In some cases, the equipment design relies on movement of the outer ring within the housing to relieve stresses from shaft thermal expansion (floating bearing). I would be cautions to use lock-tite or similar products since they may prevent this necessary movement. If in doubt, best bet is to check with OEM or someone very familiar with your equipment.

I would not recommend modifying the bearing. In one special application we have had luck machining an O-Ring groove in the bearing fit area of the bearing housing and installing a O-Ring. This was on a large fan operating on the edge of its performance curve (heavy load-high RPM). We were having repeated failures due to the bearing race spinning in the housing even causing excessivew clearance even with the proper bearing fits on new housings and bearings.