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I am currently printing PLA infused with 80% copper powder. So far I mainly used it because it looks and feels really nice and post-processing is almost limitless, however recently I have thought that metal-like filaments might actually be a good idea for gears (in case I don't want to use polycarbonate or carbon fiber PLA).

I have been researching about the material properties of copper-infused PLA and found a few studies about the "strength", however, those seem to have exclusively focussed on how much weight can be suspended on a hook where it showed pretty good results. The only other info I found was an unsourced "it is more brittle", however the objects I printed so far do not feel more brittle.

Does anyone have any experience with spur gears printed from copper-infused PLA? Are there any advantages over regular PLA? Any downsides (I could imagine higher abrasiveness is not really helpful)?

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  • $\begingroup$ You do not "feel" brittleness until you have smacked the part with a hammer lol $\endgroup$
    – AzulShiva
    Jan 16 at 8:44
  • $\begingroup$ feel, seem, appeared, made the impression. Use whatever word makes you happy and conveys "some initial tests did not make it seem all too brittle". $\endgroup$ Jan 16 at 8:49

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With the right material, you could print the gear and then sinter it, resulting in actual metal gears. However, 80 % metal-filled PLA is at the lowest border to achieve this, and a lot of that technology is patented.

FilametTM

FilametTM is a Virtual Foundry product that contains around 80-92 % metal powder of 100-400 µm particle size, suspended in a carrier. The carrier material is supposedly PLA or at least functionally similar. The resulting filament is highly abrasive, requiring stainless steel1 to print more than short sections. The high metal content also gives the material a memory of its spooled-up shape. This demands extra special treatment during printing to prevent snapping the filament in the shape of a pre-heater to get it spooled off properly. The same company also offers similar products for ceramics. After printing, the models are burned-out and sintered in an oven at very high temperatures. This sintering is done in a crucible filled with carbon and alumina, burning out the PLA carrier while retaining the shape. Their material-making process is patented (patent itself) and covers all their metal, ceramic, and glass materials.

1 - or something even more hardy, like an Olsson Ruby by 3DVerkstan

MetalXTM

The MetalXTM system by Markforged uses a special printer and proprietary Bound Powder Metal Filament that contains an unknown plastic binder. A lot of this machine and surrounding peripheries are patented and information spare. Among others, their method of creating composite filaments and their binder material, support material & sintering process are only described in patents. From their advertisement I could deduce the following process: The MetalX printer prints the item with unknown print settings, resulting in a raw item containing metal and the binder. After wash-cleaning using a liquid known as OpteonTM SF79 (Datasheet) to remove the specialty binder, the sintering happens in a free oven at 1300 °C, leaving behind a metal product. Free oven means here, that the printed part is not embedded in a filled crucible like with FilametTM.


Disclaimer: I am not affiliated with either Virtual Foundry, Markforged, 3DVerkstan, any of their products or affiliates.

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At a guess, copper really isn't that strong so you're likely to see minimal improvements, if any.

The PLA carrier plastic is still PLA, with a low melting point.

The copper won't "fuse" with the PLA, it will still be flakes of metal embedded in a tiny pocket inside of a plastic structure.

However this is all speculation, and your best option for an answer is to print some gears and methodically test them against plain PLA, and perhaps a metal gear if you can. Try and use identical setups/bearings/pressures and times.

Perhaps a high torque and a high-speed test, in both lubricated and unlubed, for PLA, copper-PLA, and a straight metal gear? That would be 12 tests in all and clear out all questions.

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    $\begingroup$ I agree with the general idea, but there have been PLAs that contain metal powder that after printing could be burnt out in a sand oven, leaving behind an object from only the metal powder... we had a question about that - FilaMet(TM) contains close to 90 % metal powder, and then the PLA carrier is sintered out. $\endgroup$
    – Trish
    Jan 12 at 7:26
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    $\begingroup$ The trick is to fuse the copper, burning of the binder. Markforged has built their company based on printers that print metal filament with a binder to sinter printed objects later in ovens to create metallic parts. I think there should be a separation between metal filaments that can be printed at home (usually for esthetics or magnetic properties and printing to create metal parts, the latter is usually not something you do at home. $\endgroup$
    – 0scar
    Jan 12 at 10:01
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    $\begingroup$ @0scar you just threw me the perfect bone to make an answer based on the Markforged MetalX as well as Filamet! Incidently, Filamet is the lowest bar to metal printing and could (arguably) be done at home. $\endgroup$
    – Trish
    Jan 12 at 10:51
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    $\begingroup$ Likely the only potentially interesting properties are thermal. Since 80% of the mass (or is that volume?) is copper you'd expect the printed part to have heat capacity closer to copper (much lower than PLA) but maybe also thermal conductance closer to copper (much higher than PLA). Whether this is a net gain or net loss for the application of gears, I'm not sure. $\endgroup$ Jan 12 at 13:42
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    $\begingroup$ @R..GitHubSTOPHELPINGICE It would also add mass... $\endgroup$
    – Trish
    Jan 12 at 18:17

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