metglass / amorphous inductor  - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: March 22, 2025, 07:53:24 pm
content: I cut a little square of this amorphous shield material I have, and I noticed this one is actually solid metal, it does not appear to have a plastic liner.Usually these are used for tape wound torroidal transformers, but I am wondering about just stacking a lamination cuttings to make a axial signal inductor. A small one, like a 1 watt resistor.Does anyone know if it works well?

author: Kleinstein
author_rank: Super Contributor
timestamp: March 22, 2025, 08:18:09 pm
content: There are quite different amorphous magenic materials. The iron based materials have high saturation, but usually also quite large magnetostriction. This can cause issues with stress sensitivity and acoustic noise.One mainly sees the magnetic properties of the core with a closed magnetic core. With just a kind of rod, much is set by the geometriy instead and the actual core material gets less important.Cutting the material can be a bit challanging as the material is quite hard.To avoid eddy currents one would still want isolation between the layers.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 22, 2025, 08:44:15 pm
content: Is your question about how to cut and machine those materials? More information please.

author: coppercone2
author_rank: Super Contributor
timestamp: March 23, 2025, 04:44:45 am
content: It cuts OK with a scissor. But if I cut it up into little squares its a waste (its not super cheap). I think its really hard though, for how thin it is, scissors should be able to cut most materials better. I am just using kleintools electrical scissors (all metal). I think if it was a little thicker it would get pushed out the front of the scissors (like trying to cut a hardened pin with scissors).It might be this onehttps://ibspot.com/products/woremor-magnetic-shielding-film-amorphous-cobalt-alloy-shielding-alternating-magnetic-fields-wmf-mcf5-3-linear-feetI have no idea why, but it looks physically like it should be possible to stack this stuff up and make a little inductorIf I had a fancy cored punch I think I could make a doughnut tooit does have akind of micro 'zipper effect' where you cut it though, so it does need to be dealt with. I am not sure how yet, If you drag a coin over it to 'burnish' it, it gets flatter but it can also tear, I thought to maybe try to flatten it with a tougher tool, like fine stone or a old gauge block or something. But those scissors I use have micro teeth in them (similar to kevlar shears). I aint try a flat scissor yetActually I have leatherman wave here, the scissors on it will cut the sheet nicely and not leave a 'zipper' that the more rough scissors leave. You can probobly drag over it using one of those oil-rubber-soft machinist stones to get rid of whatever microbur is left on the foil after cutting so it stacks nicely.AND IF You fold it over, and crease it, it does not break, it stays creased and very springy. Might be a interesting material for some kinda special micro leaf spring thingif you crease it hard (I ran a quarter coin over it on a wood desk) it does shear it.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 23, 2025, 08:59:21 am
content: What would be the purpose of the inductor and frequency range it would be used with. For many cases I don't think it would be worth it.One interesting application could be as part of a fluxgate magneto-meter. For this the material could be a really good choice. However this would want a more donut or racetrack like core shape with good precission (constant cross section). How good the material actually is can still depends on details (e.g. impurities, mechanical stress, starting crystallization). One could still also try a more tape wound version, at least for the start (get the electronic part working, which can be a bit tricky).I am surprized to see that one can get the cobald based material in such a wide foil - the ones I have seen were rather narrow (like 6 mm).I know one can get the cheaper iron based Metglass in wider rolles. AFAIK they are made up to 30 cm wide for power transformers.One can find small pieces of the iron based material in theft detection tags.

author: coppercone2
author_rank: Super Contributor
timestamp: March 23, 2025, 09:10:38 am
content: Hmm well I just want a inductor. I wonder if it will have high Mu. Because its an alternative to buying a inductor.I guess I need to try it. I have a 10 amp version of a laminated inductor which is the size of a small dumbbell, and now I want to make one that is appropriate in size for a weak rat.The interesting part is that if it works I can compare it to a similar value axial inductor of similar size and even do some basic tests on it like measure Tempco (just need to make an adapter for the DE-5000 to wire into my temperature box.So far it sounds like it might end up being a sub par component but there does not appear to be a critical flaw.I am just wondering about how to insulate them.I am wondering if you can use a stainless steel "black" on them, dip them in varnish and stack em. It looks like a handy mixture of lye, sodium nitrate and water works on stainless. I don't know if it will work on metglas. This one is only 4 % iron. I need to find a cobalt blackening solution.

author: coppercone2
author_rank: Super Contributor
timestamp: March 23, 2025, 09:49:26 am
content: also for some background, I thought the foil seems easy to work with. Laminations of a regular thickness are a total pain to work with. I scrapped one transformer to get 'lamination stock' and it took me all day and there is a hell of alot of bending and straitening.Perhaps if you can get thin silicone steel its not so bad, but with thicker sheets its definitely a big shop job. I thought it would be cool if you can get universal stock for small size signal inductors in a lab. Metglas seems like a fairly high performance magnetic material too.I think its fairly cheap if it turns out you can make parts from it, my main problem is that I figure if it does not make parts it will still make a good shield, and then I wreck my long strip (which would be useful for wrapping something in a shield). I figure I have only one or two attempts at this before the remaining strip is too short for some jobs I know it would actually work with confidence, and then I am just wasting moneyI am even thinking you can just crease the parts out without a cutting tool, which is kind of cool, if you make a bending aligner, it feels pretty macguyverI bought a fairly wide range of signal inductors (a good E-series) and its like not cheap ! and alot of storage space too. maybe this can proliferate DIY inductors.

author: jonpaul
author_rank: Super Contributor
timestamp: March 30, 2025, 12:05:48 pm
content: Hello, we used these in 1970s..1980s, amorphus mag matls break easily. Very high cst, limited shapes.Any cutting results in shattering due to xtal structure. The plastic wrap keeps the very thin materil from unwinding.This is why amorphous cores are tapewound totoids or other wound shapes.See the app notes and papers on mfg site like Arnold Mag, Magnetics Materisals, Vaccuumsmeltz.Depending on the freq range other cores are reccconend.Main point of amporphus is very low core losses esp at mains/low freq.Used in util disty trsf at mains freqj

author: coppercone2
author_rank: Super Contributor
timestamp: March 30, 2025, 09:08:31 pm
content: It looks OK when you cut it with scissors, I am telling you its like making a sandwich. it feels like cutting fine stainless mesh, its very possible to assemble a axial inductor of arbitrary specifications. I know you can buy a boring doughnut but this is like making a hoagie

author: ahbushnell
author_rank: Frequent Contributor
timestamp: March 31, 2025, 12:25:35 am
content: You need insulation between layers or you loose the advantage of laminations.

author: coppercone2
author_rank: Super Contributor
timestamp: March 31, 2025, 04:27:10 am
content: that part is TBD, not sure how to put such a thin insulation. the problem the thinner the laminations are the more insulation you needthe idea was to try to get a black coating on them and try thinned down transformer varnish. I suspect it might not work well because of low iron content, then the best idea is to put a flash-copper coating on it and oxidize that.or some kind of thin paper or plastic. Transformer laminations are highly evolved technology and they are pretty thick so there is not much info to go on for this project. May be best to get a plastic coated met-glass !paralyene comes to mind too but I heard its difficult