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why not aluminum instead of steel
By brianschanafelt, Section Newbies Posted on Sun Jan 13, 2008 at 07:25:03 AM MST
wind energy

my question is why cant u use aluminum instead of steel for your magnet rotors. if i could use the aluminum it would be lighter. but i am still not shure what would be the best way. because i have a friend that has a shop and all he deals with is aluminum and stainless steel. or could i use stainless for the rotors. thank u for the info
Kind of flooding us with newbie questions today. Always better to combine these questions for brevity. Google can be a lot quicker than the old farts on this board. Friendlier, too.

why not aluminum instead of steel | 5 comments (5 topical)

Re: why not aluminum instead of steel (3.00 / 0) (#1)
by stop4stuff on Sun Jan 13, 2008 at 03:29:39 AM MST

ferrous rotors create a pathway for the magnetic flux between adjacent magnets... this helps to concetrate the flux across the air gap (& coils) giving better performance (more watts) from the stator.

Re: why not aluminum instead of steel (3.00 / 0) (#2)
by jaskiainen on Sun Jan 13, 2008 at 03:50:33 AM MST

Hi!

Any specifications how much would aluminium plates affect to the performance?
We have a cnc machine where i work and plenty of aluminium plates, but none of steel.
Im not even sure if i can cut steel with it?
I just cant see how it would reduce the efficiency of dual rotor system?
Isnt that just the opposite N and S magnets and the airgap between them that matters?

Best regards jaskiainen

Re: why not aluminum instead of steel (3.00 / 0) (#4)
by Flux on Sun Jan 13, 2008 at 05:59:55 AM MST

Just doesn't seem possible to lay this stupid idea to rest.

Aluminium for the magnet rotors is just about as sensible as replacing expensive neo magnets with ferrite. It just doesn't work and the lower weight is no virtue either.

Flux

[ Parent ]

Re: why not aluminum instead of steel (3.00 / 0) (#3)
by fungus on Sun Jan 13, 2008 at 04:06:41 AM MST

The steel rotor is needed for two reasons;
Because it is iron and is attracted to the magnets, it boosts the magnetic field density coming out the front by redirecting it, you will lose a lot of power without them.
Again, because they are attracted to the steel it is much easier to restrain and hold them when they are trying to jump together with the opposite magnet, and from centripetal forces throwing them outwards.
Steel is also a relatively rigid material and wont flex, aluminium also has the problems of fatigue.

'Two things are infinite: the universe and human stupidity; and I'm not sure about the universe.'-Albert Einstein
Fungus - www.reenergy.co.uk

Re: why not aluminum instead of steel (3.00 / 0) (#5)
by fcfcfc on Sun Jan 13, 2008 at 08:11:29 AM MST

Hi: I can tell you that experiments I have done with a gauss meter show about a 1/3 increase in flux density when an iron plate is put behind the magnets. That is a substantial increase. A an example a 1 x 2 x 1/2" N42 on the surface will read about 3000 to 3400 on a wooden table. Put it on a steel plate and the readings will jump to about 4000 to 4400, about 1/3 more. The iron plate also allows control of the magnets when placing them. I can just imagine placing 16 neos on an aluminum plate, free to move as they wish!! Ouch!!

why not aluminum instead of steel | 5 comments (5 topical)

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