Ferrite VS Neodymium strength

[vawt]

Ferrite VS Neodymium strength
I am trying to establish the ratio in strength between the 2 types of magnets.
from what I read is that the Ferrite has a larger flux range vs the Neo.
but I need to know the strength ratio?
can anyone help me with this little challenge, size for size what is the strength
between the 2 types? 2to1 3to1 or 5to1?
thanks

sam

[vawt]

what all this info mean?!
http://www.magnet.com.au/neodymium/typical_magnetic_properties.php

http://www.magnet.com.au/ferrite/typical_magnetic_properties.php

[RP]

http://www.google.com/#hl=en&sugexp=ldymls&xhr=t&q=magnet+strength&cp=12&qe=bWFnbmV0IHN0cmVu&qesig=V5I1HEpfrUxO-vpPtNhCuw&pkc=AFgZ2tnOXRnN7dvoXfhAKGr5okcC3spi2w_HiSJDJHTaPzc6mmUJbv9YviIGoi1__VCPnGo9cMtLrOcHhr2YCJVe3zNVeAePfg&pf=p&sclient=psy&safe=off&biw=1112&bih=745&source=hp&aq=0&aqi=&aql=&oq=magnet+stren&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=1ef120049c3f5a29

[joestue]

what is it you want to know exactly?
 try reading chapter 7 of "Electrical circuit theory and technology" on google books, its about as simple as it gets.

as far as a direct comparison between ferrite and neo's,  the energy product would answer that question, neo's are about 10 times higher than ferrite magnets.

[Flux]

Without going into detail about the various grades of neo and ferrite, Neo has about 3 times the remenent flux of ferrite and about 3 times the corecivity.

The total energy product of neo is about 9 to 10 times that of ferrite.

If you are building axial ,machines then you can expect about half Br in the gap of a sensible alternator. Neo can give you about 600mT and ferrite about 200mT.

The size and weight of the equivalent ferrite based alternator will be about 8 times that of neo if you use the same design.

Flux

[vawt]

what is it you want to know exactly?
 try reading chapter 7 of "Electrical circuit theory and technology" on google books, its about as simple as it gets.

as far as a direct comparison between ferrite and neo's,  the energy product would answer that question, neo's are about 10 times higher than ferrite magnets.

thanks all for great and qiuck to help response.
my co worker has a 3kw hawt at 550rpm, it uses Ferrite magnets. his question was what if i change the magnets with Neo magnets, what extra power do i get? and what RPM.
he is hopping to drop the rpm to 300. the high rpm is causing all the problems...structure, baerings, noise...

thanks
for all the help

sam

[ghurd]

"co worker has a 3kw hawt ..."
What is it?
Rated power and an RPM do not tell anything helpful.

Probably not much difference with an iron core.  Not worth the effort, in my opinion.
The existing ferrite magnets may be much more complex than they look.  There could be multiple poles per magnet, or the poles could be skewed to reduce cogging, or....

Air core would be a huge difference, but all the operating parameters of all the parts will change.
To make it work well, the stator would require rebuilding to different specifications.

Reducing the RPM by half will most probably make the blades stall.  It will be quiet, but will not make much power.

Changing one part makes everything else act differently.
G-

[Flux]

Not enough details to remotely guess what would happen.

In most cases there would be a reduction in speed. Whether you get more out is less easy to guess. To gain from the neo the whole thing may need to be redesigned. The present output may be limited by a number of things, if it is wire size then you would not gain anything. If it was because the speed was too high for the prop then you may gain. If it is reactance limiting then neo would raise the output a bit but no significant change would be possible without reducing turns.

As Ghurd said there are other factors, simply changing magnets will not likely be sensible. I am sure you could get better performance with neo if done properly but if the whole thing is reasonably designed at present the neos you use would be much smaller than the present ferrite. Just replacing with the same size neo would almost certainly be a costly and pointless experiment.

Flux