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Small motors defect - what is the name of this defect?

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Prototyp_V1.0

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Hi.

I need some help to find the terminology for a rare kind of electrical motor fault/defect.
I've seen some toys where the small motor inside -when no load- began to make a scream-alike sound, strong vibration and a rapic decreased rpm.

In some cases, it help to apply oil to the bearings, but not always.

I just wonder - what is the main reason for this misbehavior, the bearings or is it the motor itself that isn't balanced?

Reason I ask is I have a citchen mixer that have this problem. I might have to do something with he motor, because it behaves like this.

Thanks
 

I've had devices do the same thing after extended use. It usually come and go. (Shavers, refrigerator fans.) I believe the inexpensive brass bearings get worn. The motor shaft wobbles within the enlarged hole, causing the screaming sound and decreased rpm.

A bit of oil quiets it for a while, if the area is accessible. I have never heard of an easy way to cure it.
 

Terminology? how about "worn bearings"?

With a kitchen mixer I would be worried that food has gotten into the motor and the bearings got worn due to the food/liquid getting into them (food/liquid doesn't work well as lubricant, maybe social lubricant would work ;-)). This is actually one of the typical failure mechanisms of that TV blender "Magic Bullet" a bunch of reviews of that blender cite leaking of the bullet container into the blender causing first noise then complete failure of the motor.
 

No, the motor part is on top. That is also why I'm reluctant to use any oil - won't have it in the food.

I still cannot find any videos on youtube that cover the same type of failure. Those videos I heard the sound from, is more kind of "metal against metal" and not the high pitch "wobbling".
 

I still cannot find any videos on youtube that cover the same type of failure

Be the first person to post a video that depicts this problem.
I'm now curious to know how it is.
 
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    CataM

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Over time it grows in volume and persistence. I picture that I could squeeze the bearing in a pliers, in the notion that the loose play is so small (a thousandth of an inch?) that I could take it up by applying pressure. But I'm sure that would not work. If the bearing could be compressed at all, then I think would bind the shaft, ruining the motor.
 

I think post #5 is a good advice :smile:. I am curious as well.
 

I have a sound record now - pretty good quality too

Hi.

I've done a sound recording of that citchen machine. I did use some time because I needed to get in hand some mocrophones for this.
https://soundcloud.com/random-stereo-sounds/kjokkenmaskin

Actually - when I listen to this record it stroke me that on this particular machine, there could be something else than a bad motor.

The record is done by microphones mounted on the surface of the casing, so it's more clean than I hear with my ears a meter away.
 

A faulty relationship between the rotor and stator is also called an eccentricity.
 

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