Motor Bearings
Motor Bearings
(OP)
We have two 150 HP 480 VAC motors that had bad bearings that cooked/fused themselves to the motor shaft. Our local motor shop had to cut, heat and pull the internal bearing races off the shaft. This damaged the shaft pulling some of the shaft off in the process of pulling.
My question is: If we have our local machine shop build up the damaged motor shafts by welding and turn (lathe)the built up weld back down will these motors still be reliable? Our local motor repair shop is telling us they will not be reliable after this shaft repair.
These motors are running a critical process that need very reliable motors 24/7 - 365.
My question is: If we have our local machine shop build up the damaged motor shafts by welding and turn (lathe)the built up weld back down will these motors still be reliable? Our local motor repair shop is telling us they will not be reliable after this shaft repair.
These motors are running a critical process that need very reliable motors 24/7 - 365.





RE: Motor Bearings
Another possibility for repair is to chrome plate and grind or build up the area with a metal coating process that's machinable with lathe tools.
RE: Motor Bearings
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(2B)+(2B)' ?
RE: Motor Bearings
What they damage? The inner bearing fit?
If yes, the shop most verify the shaft straightness, if is OK you can repair that fit by Welding and machinning process,this practice is common and I don´t see the problem,the only is the shop most use the correct tolerance for the bearing fit.
Regards
Carlos
RE: Motor Bearings
Why? If you repair the motor anything that later goes wrong will be blamed on that repair. And you will have little defense, because the motor shop told you so, etc.
RE: Motor Bearings
Had the ball/roller bearings spun on the shaft, if not what where your repairers doing to trash the shafts. (remove bearing cage, drop out balls/rollers and off with the outer track. ready with extractor for inner track, add lube to fit and torch inner track with oxy-acet. lube. extract some, cool shaft, heat track, lube, torch, lube, extract an-on.)other wise grind off (a flat)on inner track to break interference fit, then remove.)
As the shafts are shaged, check rotor all over for run out between centers (dont worry about shaged bearing fits), if ok consider repair.
Possible repair is skim shaft,sprayed metal build up and grind to correct fit or PRECISION turned, mounted in bored soft jaws and a center or between centers.( no bruised centers in shaft !!)
All in all could put you out of action for a bit, If you can stretch to it some new motors and repaired and tested motors in hand. Coffee Please !
Dom
RE: Motor Bearings
RE: Motor Bearings
I agree with the other comments about trusting the repair agent. If they are reputable, trust them and act on it accordingly.
RE: Motor Bearings
RE: Motor Bearings
RE: Motor Bearings
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Also here is a previous eng-tips thread on similar subject:
thread248-49516: Electrical Motor Shaft Repair
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(2B)+(2B)' ?