PUMP MOTOR
PUMP MOTOR
(OP)
Hello,
this question is in relation to grinding material from the feet of a Thyseen Type 6X13SVC-L Pump.
We recently ground 6mm from the 50mm thick feet of the motor for our pump.However, we wer later told that this would make the motor unstable etc and this was not good practice. Can anyone give me any insight into why this might be the case?
Thanks in advance,
Alan
this question is in relation to grinding material from the feet of a Thyseen Type 6X13SVC-L Pump.
We recently ground 6mm from the 50mm thick feet of the motor for our pump.However, we wer later told that this would make the motor unstable etc and this was not good practice. Can anyone give me any insight into why this might be the case?
Thanks in advance,
Alan





RE: PUMP MOTOR
If I understand your question correctly...
You ground 6mm from the feet of a motor, then someone said that this would make the motor unsuitable for the intended use.
The only reasons that I can think of is that there might be a problem with the strength of the mounting foot.
OR
The possibility of creating a "soft foot" on the motor. The "soft foot" is the case of the old milk stool with 3 legs is always stable but add a 4th and the stool will rock.
Hope this helps.
RE: PUMP MOTOR
Your use of the word "Grind" tends to suggest a less then perfect machineing process was used. This may or may not be the case.
however a very flat surface shold be used for the mounting, so the the forces are spread out evenly over the surface of the footing.
During your normal motor allignment process It should be standard practice to use Shim Material that at least equals the area of the foot pad.
If a High Spot is created by the Grinding process then the forces of the motor torque, (or even just the weight of the motor,) could cause this high spot to be flattened over time, resulting the footing becoming loose.
Perhaps this is the instability they refer to.
Good Luck
Tom
RE: PUMP MOTOR
Why was 6mm ground off?
I don't recognize the machine description. Is it horizontal or vertical? Flange or face mounted? Pump mounted separate from motor? If so was alignment adjusted after shimming feet?
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RE: PUMP MOTOR
Regards
pennpoint
RE: PUMP MOTOR
("grinding" covers a number of areas -- most of you are probably thinking of a hand grinder which is far from precise -- however, there is also machine grinding which can produce a very fine surface and is used in place of what we usually refer to as machining in certain applications) i.e. it is preferable to "stone" (or grind) a commutator... many motor commutators are machined, but generator excitors are usually "stoned"...
RE: PUMP MOTOR
Are approx 2.0 inches thick, and you removed approx 1/4 inch off them. I would have instead, removed material from what ever the motor is intended to be mounted on. Or shimmed up what ever the motor was to be connected to, if that was done for an alinement issue. If they "were" approx 2 inches thick. That is a pretty good size motor. And if the manufacture made them like that, then they did it for a good reason. What kind of material is it? If it is something other than steel, you may have weakened them.
RE: PUMP MOTOR
thanks for the replies.
Just to make it clearer: The feet are made of Cast Iron, and we are worried that the structural integrity of the motor might be damaged du to the grinding. When I say grinding I mean that material was machined fromthe feet, exactly like "Pablo02" said. I don´t, however, understand how the internal structure of the motor could be damaged. One of the guys here says that due to vibrations there could be some damage done, but can´t explain what type of damaged - any of you ever heardof anything like this?
The reason we didn´t shorten the foundations on which the motor stands, is beacuse it would take too long and we need the pump to be operational as soon as possible.
We would have put some shims under the pump, but if we did that then we would have to work on both the suction and discharge lines and that would also take an age, which is why we opted for the easy option of machining the feet!
...anyways, 3 hours after I posted this thread the motor bearing failed, wnd we don´t know why! Any ideas? Of course they´re blaming us because we machined the feet, but they can´t prove it!
Hope you guys can give some insight. thanks.
A
RE: PUMP MOTOR
RE: PUMP MOTOR
RE: PUMP MOTOR
But there are certainly other possibilities. Did the alignment change?
Regarding your feet as I said if this is a 2-pole motor you had pretty high vibs (did you measure them?). Vibration can certainly damage bearings but usually it doesn't occur that rapidly.
Best way to answer your question is a thorough inspection of the machine and failed bearing.
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RE: PUMP MOTOR
I do not think 6 mm removal from a 50 mm base will affect its structural integrity greatly.
RE: PUMP MOTOR
RE: PUMP MOTOR
RE: PUMP MOTOR
thanks again. Still not confirmed the cause for the bearing failure!
When the motor was put back we used "Optalign"(lasers alignment equipment) to align the couplings, without any difficulties!
I appreciate the point about the tensile strenght of cast iron, but there are no visible cracks, and we´re not in a position to test internal cracks, and I´m not sure if that would affect the bearings anyways?
The Lubrication used was correct, unfortunately, because that would have been an answer to the problem!
We didn´t measure the vibrations, but I like that theory - don´t know if the other engineers will buy it and I don´t know how to prove it? :) Any ideas?
Cheers,
A
RE: PUMP MOTOR
What happened to the original motor that was removed? What failed on it? Is there a chance that an integral pump motor combination is available to do that job? You may have mounting plate, alinement and drive coupling issues. Is the mounting plate thick and strong enough? What kind of coupling is used?