Aluminum parts for the motor internals

[magudaman]

I have a BMC brushless motor that is basically a large out-runner inside. I was curious if it is possible to rebuild this piece in the photo but make it out of aluminum. The current piece is quite heavy and I was considering using a 7075 shaft or hollowed hardened shaft.

I am guessing the steel here helps with some sort of magnetic properties but not really sure, could have just been a good material.

 

[thepronghorn]

If you're talking about the part around the magnets, that needs to be steel unless a the magnets are in a halbach array, however the rest can be whatever material you would like as long as it's strong enough and can handle some heat from the stator.

 

[Chalo]

Most strong aluminum alloys begin to permanently lose strength at less than smoking hot temperatures. That may or may not be a big deal depending on how conservatively the part is designed. In this case it seems like a shaft failure could have safety ramifications.

Chalo

 

[magudaman]

If you're talking about the part around the magnets, that needs to be steel unless a the magnets are in a halbach array, however the rest can be whatever material you would like as long as it's strong enough and can handle some heat from the stator.

Yes. So it could be really cool to make just the magnet backing out of steel then create a sort of spoke design out of aluminum that would bolt to the magnet ring then go inward to a splined hole. Then I could easily change out shafts with different diameters and materials.

Most strong aluminum alloys begin to permanently lose strength at less than smoking hot temperatures. That may or may not be a big deal depending on how conservatively the part is designed. In this case it seems like a shaft failure could have safety ramifications.

Chalo

That's is a good point. I would normally assume that the motor would not exceed 200f, which I believe most aluminum could handle.