That's not what I'm talking about at all. That's basically a mixture of resin and copper dust. In terms of creating a motor coil it's highly unsuitable. By filament I'm referring to a metallic strand, what would be called "fiber" in this case, but I simply refuse to call thin copper wire a fiber.
There are big problems attempting to build an electromagnetic inductor using conductive resin made from a mixture of metal dust and plastic.
#1: conductivity is not guaranteed and may fluctuate drastically and result in a lot of impedance, resulting in a lot of heat, probably resulting in a melted coil at exactly the point of bottleneck, it'd blow like a fuse.
#2: the conductive bead laid down would require some sort of non-conductive insulation in order to form inductor coils, would this be a surface coating, perhaps some sort of paint, or more resin of a different sort?
#3: the resolution of the deposition process would restrict the winding density and also the proximity of the windings to each other.
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In terms of creating an electrical conductive resin or ink, generally silver is required to produce a high enough conductivity, which is how most conductive glues and resins currently work. Carbon nanotubes have also been tried.
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What I'm talking about is enamelled copper wire laid in precise patterns within the resin material. This would permit the creation of novel types of potted inductor integrated with formed mechanical parts. An insulated solid metal wire is very different in electrical properties compared to a printed resin conductor. In terms of the thickness of the wire, heavy gauges might be a big challenge, but thin gauges as found in small servomotors could probably be achieved with the existing machine.
It's the ability of the machine to align and position fibers precisely within the resin that's the killer and unique feature of this device, to my mind a good conductor is the missing piece of the puzzle. Copper is not the only possible metal, either. Steel would be pretty structural, although it might cut into the nylon due to hardness incompatibility, if used in the correct pattern it would be stronger than vanilla nylon.
The other feasible option I can think of to make electrically conductive fiber is that carbon fiber can be electroplated, typically used in military aircraft for electromagnetic shielding, so an electrically conductive copper-plated carbon fiber coated with an insulator might already be available. Given non-insulated fiber, one could make thicker conductors by layering the fiber with minimal resin.
Different software for designing the conductive parts might be required, but having a mechanically-resilient potted carbon-copper fiber coil probably would improve the performance of an induction motor or transformer, especially given the ability to print copper fiber and steel fiber 2d-layered in arbitrary configurations.
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As-is the nylon carbon & kevlar reinforced parts are some of the most mechanically rugged parts that can be additively formed, and nylon is quite compatible with other materials, wood, metals, plenty of feasible glues, so it's a highly stackable process, can mix materials fairly arbitrarily, so as a general-purpose temporary or permanent interface material there's a lot of options that get opened up.
Nylon can also be electroplated with various metals, typically nickel and chromium, which can improve the wear characteristic and also permit the design of electrical connectors.