Moldable Iron Powder

Let Effective permeability = ue Material permeability = u Total length = le, the total length of the magnetic circuit Gap length = lg, the length of the non magnetic part

Then ue = u * le / (le + lg * (u-1))

For packing fraction of 0.8, you can say le = 1 lg = 0.2 u = 10000 ( say for iron )

ue = 5 approx

See the problem ?

...

OK, I get it now. There's much higher gap sensitivity because of the multiplier of the 'u-1' factor. It also implies that my 'average' (arithmetic mean) on the gap is wrong, there's much more flux at the near-contact points than predicted, so we might expect anywhere from ue=3D20 to maybe ue=3D150.

Hotpressing of iron powder would increase the contact area significantly, which is why powdered-iron cores work well; that wouldn't be available in the field doing onesies, because of the powdered-iron-burns-and-oxidizes problem.

If you're desperate, you could fab some kind of shroud around your press, and flood it with nitrogen or argon or maybe SF6...

Cheers! Rich

F*ck you.

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

Might try picking these up, too:

PDF files worth reading. (Found them using David's name, above.)

Jon

Look for sintered metal in a magnetic material. I think some magnets are made with sintered iron.

I wish this had come up 5 months ago, when I was taking down Ceromet/MPP in Anaheim, California.

I could have gotten you guys a few thousand pounds of iron powder for free.

If you want a few pounds..maybe I can get it from another company if I ask nice and they want a service call.....

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

Hell, NO! They're clearly liberals. They lollygag around the house expecting their human servants to deliver pre-chewed food to their face and schlep away their s*it, while they mutilate the furniture, piss all over everything, and sneer at you.

Hope This Helps! Rich

:LOL..

Ill have to change that sig..you make sense.

Gunner

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

Um, better hurry up! ;-)

Cheers! Rich

Let the Record show that Gunner Asch on or about Mon, 30 Nov 2009 22:09:40 -0800 did write/type or cause to appear in rec.crafts.metalworking the following:

Cat's aren't liberals. Cats just recall when they worshipped as gods. Which they still believe was only right and proper. I'd say today, they're more absolute monarchists. And the only ones who matter are other members of the aristocracy. But I still like the fuzz balls.

- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!

As do I.

So the sig stays!

Gunner, with Fughead the kitten, curled up in his lap.

"Aren't cats Libertarian? They just want to be left alone. I think our dog is a Democrat, as he is always looking for a handout" Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls. Keyton

I dunno about the ability to meet your requirements, but there are iron powders available for various uses, from toys (Etch-A-Sketch), to industrial uses.. electromagnetic clutches/brakes for machines. These examples are moderately coarse powders.

Very fine iron/steel particles are a byproduct of etching/cleaning or pickling steel products in manufacturing. The steel parts are pickled in various acids, and the particles which are suspended in the liquids are then filtered to remove the particles from the acids. The result is a mud/clay-like material that is used to manufacture other products, including iron composition cores for certain magnetic properties.

I don't have any sources to recommend.

-- WB ......... metalworking projects

The finest iron powders are called "carbonyl iron"

Googling for carbonyl iron brought up this supplier: .

Joe Gwinn

--Hey speaking of doing stuff with metal powders have you seen Bathsheba's process description yet?

-- "Steamboat Ed" Haas : Currently broke and Hacking the Trailing Edge! : looking for a job...

Many years ago, the ferrite factory for which I worked used oxide from the steel mills as a raw material. I was told there were mountains of the stuff in West Virginia. To be usable for magnetics, the oxide would have to be fired in a cycle that included high temperatures and witchcraft.

Kevin Gallimore

Zone refine. Melted in a magnetic field and the field is moved slowly towards an end - moving impurities with it.

Expensive refining but quality product. Similar to that of a semiconductor process. Likely from the ferrite business.

Mart> Wild_Bill wrote:

and a further reply - iron powders are used in spray-metal applications but at a price

I've often wished that someone would make enameled soft iron "winding" wire. Then I could reverse the process - make up an arbitrarily complex winding on a simple bobbin, then wind the iron onto the copper "toroid" (all in a single pass of course). Tony