Is it possible to make better ferromagnetic filament?

A project log for Measuring BlackMagic3D's ferromagnetic filament

Measuring hysteresis curve to determine how useful is that stuff for building motors and magnetic circuits

DeepSOICDeepSOIC 04/17/2016 at 22:173 Comments

So, did BlackMagic3D fail to make a useful thing because they haven't worked/researched hard enough, or the idea of 3d-printable ferromagnetic material is doomed from the beginning?

I don't have the answer, but I have a guess. To make something go smoothly through extruder, one needs to put quite a lot of plastic into it. A wild guess will be 60% by volume has to be plastic.

Ferromagnetic particles can have permeability that is very high. But it probably doesn't matter how high it actually is, because as it is mixed with non-magnetic material, the gaps between particles will probably become the dominant reluctance of the system, and will totally determine the permeability. So, it will probably make little difference to mix in particles with a permeability of 100 or of 100000. It will look more like a gapped inductor with a huge gap of 60% or so of length of magnetic circuit. That is, like made of material having permeability of about 1/60%, i.e. about 2.

So, to me it looks like the idea of making 3d-printable ferromagnetic material by adding metal powder to plastic is fundamentally doomed. But I would love to be proven wrong on this opinion.

PS. Do you think a material with permeability of 2 is useful for something? Post a comment! So far, I haven't invented any application.


Nyles wrote 04/09/2018 at 02:16 point

Thanks for the info - one of the parts of my contest project is making a custom magnet to work with something like the AS5311 encoder, so being able to 3D print the magnetic ring would be really cool.  At least I don't have to run down that blind alley - thanks again!

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Nyles wrote 04/08/2018 at 19:43 point

Is it possible to magnetize this material?  If so, it might be useful for making encoder rings or strips for use with sensors like the AMS AS5304.

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DeepSOIC wrote 04/08/2018 at 20:16 point

You cannot make a permanent magnet, there is almost no hysteresis in the material. However, you can place a magnet nearby, and that will make the material behave like a magnet. Then you'll have to tweak the magnetic field sensor, so that magnetic field of permanent magnet is below threshold, but when the field of ferromagnetic filament adds, it goes above threshold. Sounds like it may be a bit tricky, but totally doable.

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