samarium cobalt tuning rotors

[crazyjr]

Whats up with this? How close is the power between neo and this? I know you built it Primarily for heat resistance, but does the motor lose any power to the neo setup?

Originally Posted by crazyjr

Whats up with this? How close is the power between neo and this? I know you built it Primarily for heat resistance, but does the motor lose any power to the neo setup?

Neodymium (Neo) vs Samarium Cobalt (SmCo)

The output power of both of these rotors are very similar. Our motor design is based on a 28 MGOe energy product magnet and the SmCo is also rated at 28 MGOe (MegaGauseOerstead). The difference comes into play as they heat up. Since the SmCo Rotors have a very high coercivity (coercieve force), they are not easily demagnetized. Thus the SmCo Rotor can tolerate about 250-350 degree F more temperature rise than a Neo magnet before they began to lose their magnetic power.

The Curie temperature of a Neo magnet is around 320 degree C and SmCo magnets is around 800 degree C. What this means is if you heat a magnet without an external magnetic field the magnet will lose all its magnetic properties at the Curie temperature.

Also the coefficient of remanence of a SmCo magnet is about ¼ of Neo (-0.03%/C vs -0.12 %/C). Remanence is an indicator of materials ability to hold magnetization (magnetic storage). The lower coefficient shows a ¼ lower loss of magnetic force due to increase in operating temperature.

Of course you cannot run the motor this high a temperature due to other components in the motor but it will make the motor output power stay flatter for a longer time.
Bob Novak

[E-Revonut]

Thanks for the expanation! I just ordered a Premium Balistic Spec motor last week and didn't see this then but seen it when I went on tonight. By the way I received my motor today and won with it tonight. Awesome motor, well worth the extra money!!!

[snellemin]

Will the Ballistic 8 motors have this Cobalt stuff as an option?

[NovakTwo]

Originally Posted by snellemin

Will the Ballistic 8 motors have this Cobalt stuff as an option?

Apparently, we do have SmCo magnets for testing in the B8.

[snellemin]

Originally Posted by NovakTwo

Apparently, we do have SmCo magnets for testing in the B8.

NICE!!! I want/need one for the Delta wound motor for some more gearing.

[suicideneil]

Obvious question time: What is the price like on SmCo vs Neo?

[NovakTwo]

Originally Posted by suicideneil

Obvious question time: What is the price like on SmCo vs Neo?

Depends on what day it is....

For a while we couldn't even get quotations for our Neo rotors; so, it's both price and availability. Neo rotors require an additional rare earth material that is also very expensive and sometimes hard to get----I think that it is dysprosium.

[NovakTwo]

We added a tech note ( PDF format) linked from our home page / right column:

TeamNovak

[snellemin]

I'm guessing the cost is going to be higher. Astro Flight motors uses the same smco stuff and their motors are pricey.

[crazyjr]

So basicly the design is two-fold, 1. the rotor will almost never demagnetize, and 2, brakes will never fade in theory. Nice ideas for racing

[snellemin]

But isn't the Cobalt stuff a bit more brittle?

[NovakTwo]

Originally Posted by snellemin

But isn't the Cobalt stuff a bit more brittle?

Yes, it is. It must be handled more carefully when outside the motor. We did a complete incoming inspection and there were very few dinged in transit from China. We also perform torque-tests on all rotors to make sure the magnets have been glued to the shafts properly.

[ta_man]

Originally Posted by NovakTwo

Yes, it is. It must be handled more carefully when outside the motor. We did a complete incoming inspection and there were very few dinged in transit from China. We also perform torque-tests on all rotors to make sure the magnets have been glued to the shafts properly.

If these are coming from China, arean't you exposing yourself to the same pricing instability for these as with the Neo magnets?

[NovakTwo]

Originally Posted by ta_man

If these are coming from China, arean't you exposing yourself to the same pricing instability for these as with the Neo magnets?

During the availability/price crisis of last year, the SmCo prices didn't skyrocket like Neo. I don't think that rare earths can be mined affordably anywhere else; so China will be the supplier. China completely closed their Neo mines for a period last year.

Many motors, of all sizes depend on Neo for magnet material; the situation affected other motor mfgs, not just R/C. When Adnan went to China on his last trip, he visited one of the Neo mines and met with additional mfgs who can fabricate rotors. Sourcing magnet materials will be a continuing problem.