Shaping magnets (cast)

[EmaEm1]

Hi guys!
I am wondered if alnico magnets could be molten and poured out again. I am asking this because I can buy only magnets in blocks and other larger shapes. I would make molds out of magnets I took from pickup I opened and disassembled (learning by practice ), and then melt larger magnets and pour out in molds.
It can be done with aluminum, but what impact other elements have? What temperature is needed and what are limitations?
P.S. One bit radical idea is to actually made magnets out of raw materials

I appreciate your help!!!

[Jazz P Bass]

Actually that is how the Alnico magnets are manufactured.
Casting.

Or sintered.

Here is a good read with material property links: Alnico Magnets - Integrated Magnetics

[J M Fahey]

Hi guys!
I am wondered if alnico magnets could be molten and poured out again. I am asking this because I can buy only magnets in blocks and other larger shapes. I would make molds out of magnets I took from pickup I opened and disassembled (learning by practice ), and then melt larger magnets and pour out in molds.
It can be done with aluminum, but what impact other elements have? What temperature is needed and what are limitations?
P.S. One bit radical idea is to actually made magnets out of raw materials

I appreciate your help!!!

Technically it can be done, but is well beyond what can be accomplished in a home workshop:

The elements for the Alnico are put into a furnace (an induction furnace is commonly used) and are melted at 1750-1780 deg C

To boot, it's cast into molds and while cooling it's subject to a strong magnetic field to orient micro magnetic particles inside the same way, so it gets stronger (usually along the axis) .

[jack briggs]

To boot, it's cast into molds and while cooling it's subject to a strong magnetic field to orient micro magnetic particles inside the same way, so it gets stronger (usually along the axis) .

This would be for unisotropic (oriented) grades, not A1, A2 or A3.


cheers,

[LtKojak]

Hi guys!
I am wondered if alnico magnets could be molten and poured out again. I am asking this because I can buy only magnets in blocks and other larger shapes. I would make molds out of magnets I took from pickup I opened and disassembled (learning by practice ), and then melt larger magnets and pour out in molds.
It can be done with aluminum, but what impact other elements have? What temperature is needed and what are limitations?
P.S. One bit radical idea is to actually made magnets out of raw materials

I appreciate your help!!!

https://www.youtube.com/watch?v=noGGcyPHtdI

Knock yourself out.

HTH,

[EmaEm1]

Actually that is how the Alnico magnets are manufactured.
Casting.

Or sintered.

Here is a good read with material property links: Alnico Magnets - Integrated Magnetics

Well that is some basic knowledge, i know that, but i am interested in making them at home.

https://www.youtube.com/watch?v=noGGcyPHtdI

Knock yourself out.

HTH,

Hmmmm, i will

[Jazz P Bass]

This would be for unisotropic (oriented) grades, not A1, A2 or A3.


cheers,

I believe the correct term is 'anisotropic'.

anisotropic isotropic preferred direction of magnetisation - supermagnete.de

Being that an isotropic magnet (placed in a magnetic field as it is molded) is stronger but it can only be remagnitized in one direction, my question would be "what type is 'best' for pickups"?

Or is there not a best, maybe a better?

Just curious.

[J M Fahey]

I believe the correct term is 'anisotropic'.

anisotropic isotropic preferred direction of magnetisation - supermagnete.de

Being that an isotropic magnet (placed in a magnetic field as it is molded) is stronger but it can only be remagnitized in one direction, my question would be "what type is 'best' for pickups"?

Or is there not a best, maybe a better?

Just curious.

It's the other way.
Isotropic is the unprocessed magnet material , magnets inside have "tiny magnets" called "magnet domains" and are oriented at random.
So you can magnetize well those pointing along the magnetic field (the magnetizing coil axis ) , poorly those diverging by some angle and not at all those perpendicular.
Advantage? (besides cheaper price): you can magnetize them any way, and easily into complex magnetic shapes; a ring or disk can have, say, 12 or 16 "poles" all around in a star shaped field, good for stepper motors and such.
Disadvantage: you get weaker fields.

Anisotropic: when molten or at least above some (very high) critical temperature, microscopic "domains" are free to turn, so you can orient them pointing all in the same direction.
You let it cool below that point (they might still be red hot though) and when you turn magnet off, they stay there.

You get stronger magnetization (almost 2X) on axis, very poor any other way.

Personally I make speakers so I want maximum magnetic flux all the time, won't even consider isotropic, if I were a pickup maker the same, but I can understand that some classic pickup might have used the weaker ones.

If that's needed for authenticity, please be my guest

[J M Fahey]

Well that is some basic knowledge, i know that, but i am interested in making them at home.

Ok, they *can* be made, not exactly at home but in some small factory space.

The basic question is, do you know what are you getting into?
Alnico is just a special kind of *steel* .
In fact it's a very hard one, impossible to work except by grinding, you can't drill, saw, mill or lathe turn it , it's as hard or harder than regular tool steel, go figure.

That's why shapes are made by casting, then important surfaces are ground parallel and flat.

I bet standard pickup magnets are cast into bar shape and cut to length with diamond wheels.

To melt them you need an induction oven, guess minimum power should be around 5 kW given you want to start with a large ingot and melt it into smaller bar and rod magnets.

Plus you need to be able to make the sand dies, a safe space all around (you will be working with thousands degrees liquid steel) , protective clothing and masks, etc.
Plus grinding/cutting machines and wheels, etc.

To put it into number$$$$ , you'd need a starting capital between U$20000 to U$50000, you should enroll a Metallurgical Engineer in the project and then have a guaranteed Market to sell, say, at least U$100000 worth of magnets a year, if it's a small operation (2 or 3 people living in Bosnia) and probably 5X as much .

The option is to get, say, U$1000 to U$5000, order a nice batch of proper size magnets from some International supplier , and pay import duties, tax, bribes, whatever to get them home.