25,000 RPM Bushing materal?

25kRPM is not really the realm of greased bushings. Bushings are for low speed-like in the hundreds of RPM.

What is the source of heat? Have you checked the outboard bearing/bushing? Bent shaft?

Is this an air grinder or electric?
 
What diameters are the bushing surfaces? Making a bushing 1/8" diameter survive at 25,000 rpm is pretty simple, depending on loading and other dimensions. Doing so at 24" diameter is not so easy... Grease will probably not be part of the picture, regardless of diameter.
 
I have a Precise die grinder from years back similar to this one , it's 80,000 rpm though . That thing cranks up and scares me with a 1" wheel or bigger . Don't know what kind of bearings or bushings are in it , but there must be something good out there that works .

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Cooter Brown said:
Crack it open and take a look at those bushings/bearings lol
Click to expand...

I may have to do just that . Last time I went to use it , it didn't run . ( I didn't check the fuse , just used another grinder ) .
 
Air bearings work really well at super high speeds, depending on the radial and axial loadings and rpm. They do not handle significant loading. Another option is air with a continuous mist of light turbine oil.
en.wikipedia.org

Air bearing - Wikipedia

en.wikipedia.org en.wikipedia.org
25,000 rpm is achieved by many common hand held air tools, like die grinders, using fairly ordinary ball bearings and air tool oil to keep them lubricated and cooled.
 
A die grinder has to be able to deal with the radial loading and axial loading as well as the high rpm. Quality ball bearings would be my choice.
 
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