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MAfzal
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Join Date: Sep 2012
Location: Pakistan
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Motor Shaft Re-building and Covers Re-sizing

07/18/2013 11:41 PM

I wanted to know the opinions of forum members on following two activities which we do during motor overhauling.

1. If the rotor shaft fails run-out test we re-build it. It is done by welding the metal onto the shaft & then machining it to achieve proper size & run-out.

2. If Bearing housings in the end covers are out of size/housing dia has increased beyond tolerance what we do in our workshop if is cut a portion of housing & inserted a cast iron bushing. After the bushing has been installed on the end cover, the inner dia. of bushing is adjusted accordingly via machining.

If you guys know or have come across any better ways of solving these problems in your experience then do share. Looking forward to your replies.

Regards,

Muneeb Afzal
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Pathfinder Tags: bearing housing cover sizing motor motor overhaul overhauling shaft rebuild
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Tornado
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#1

Re: Motor shaft re-building & Covers re-sizing

07/19/2013 12:53 AM

As far as I know, those are the classic good ways to make such repairs, but here are some other possibilities:

*Worn shafts can also be built up be spray deposition of new metal.
*Sleeves may be available that can be pressed on after turning the shaft, eliminating welding.
*For the end housing, bushings of correct i.d. may be available, so that you need only to machine out the socket.

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MAfzal
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#2

Re: Motor shaft re-building & Covers re-sizing

07/19/2013 1:45 AM

" Worn shafts can also be built up be spray deposition of new metal." that is interesting will explore it further.

Also what in your experience is the maximum no. of times it is recommended that shaft rebuilding & covers resizing should be carried out. E.g after shaft has been re-built x no. of times it is now time to move for shaft replacement & similarly for covers if re-sized x times then it is time to find replacements.
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PWSlack
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#3
In reply to #2

Re: Motor shaft re-building & Covers re-sizing

07/19/2013 4:44 AM

http://en.wikipedia.org/wiki/Thermal_spraying

It sounds as though more rigorous attention is needed to the lubrication arrangements of the bearings for these shafts in order to reduce or eliminate the need for shaft rebuilding during the economic lifetime of the machine. Is there an alternative "sealed for life" bearing arrangement that would eliminate the wear and the consequent need to rebuild (rhetorical question - NNTR)?

Further, is there a process materials containment problem that, uncorrected, is causing dust or other abrasive materials to accumulate in the neighbourhood of the motor bearing and its lubrication system (rhetorical question - NNTR)?

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TonyS
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#4

Re: Motor Shaft Re-building and Covers Re-sizing

07/19/2013 7:49 AM

It would help if you say what type of bearing. Sounds very much like Babbit bearings to me. If they are then you need to take a careful look at the lubrication if they are failing on a regular basis.

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MAfzal
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#8
In reply to #4

Re: Motor Shaft Re-building and Covers Re-sizing

07/22/2013 4:28 AM

Ball bearings 62XX/C3 & 63XX/C3 type.

Working on Lubrication regime.

My query is more related to ' what's the best method of repair after damage been done'. Of course the best is that damage be prevented in the first place
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TonyS
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#9
In reply to #8

Re: Motor Shaft Re-building and Covers Re-sizing

07/22/2013 9:05 PM

Metal spray if the motor is worth it.

I don't know your situation with these motors, but if you are getting regular shaft wear failures with ball or roller bearings, something is seriously wrong. Misalignment or over tensioned belts spring to mind.

Anything under 60HP I threw in the scrap bin. Not worth the time and effort to repair.

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fixitorelse
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#5

Re: Motor Shaft Re-building and Covers Re-sizing

07/19/2013 9:35 PM

Very hard to Comment given the small amount of data presented. What size shafts are you building up with weld. Are you line boring housings so they are true. Many other questions that you can see will pop up in this process.

More details required.
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rudy.leurs
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#6

Re: Motor Shaft Re-building and Covers Re-sizing

07/20/2013 5:19 AM

Due to welding, the shaft may bend

There may arise tensions in the shaft and the shaft can break.

Remember that the shaft is subjected to mechanical fatigue.

If there is a belt pulley on the shaft, the shaft bends at each revolution

Is the type of steel which the axis is made​​ of the right quality?
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ppremram
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#7

Re: Motor Shaft Re-building and Covers Re-sizing

07/20/2013 12:06 PM

These are the methods we are following in the Refinery , any body knows better method , let us share it
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fixitorelse (1); MAfzal (2); ppremram (1); PWSlack (1); rudy.leurs (1); TonyS (2); Tornado (1)

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