Metal 3D printing filament

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Scott_M

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I received an email from online metals today, they are now selling metal, ceramic and glass filaments.
https://www.onlinemetals.com/en/3d-...eh=bfeb580e19bf40591&utm_campaign=3d-printing

Basically it is metal with a binder that is burnt out in a kiln afterwards, I know nothing about this but thought I would post it for others. I do have a nice Bambu labs P1S printer but do not have a kiln. I have been meaning to build a heat treat furnace so maybe in the near future I can try this.

Here is the Guide https://www.onlinemetals.com/en/gui...eh=bfeb580e19bf40591&utm_campaign=3d-printing

The aluminum spool is $150.00 but Iron is "only" $80.00

Interesting how far the capabilities of the home shop have come. Will be interesting to see how this plays out.
Scott
 
When you consider that the filament contains 20-25% plastic, and you burn out the plastic, I was expecting shrinkage of more like 20-25% to get a solid part. If it's only 7-10% shrinkage then the object will most likely be very porous, kind of like an aquarium bubbler.

Many years ago I read a white paper, or maybe saw a video, about a very impressive 3D printed metal dragon door handle. They were using a process where a layer of metalized powder was spread out, an adhesive was "ink-jetted" onto the areas that you wanted to stick together, UV cured, then another layer of powder was spread out....rinse, lather, repeat ad-infinitum. The 3D object was extracted from the powder, cleaned, and sintered. You then had a very porous metal object, I think they used stainless-steel powder. This object was then put in a kiln in a special crucible along with metal of a lower melting point, bronze I think. This whole mess was then brought up to, and held at, that melting point for many hours. The original object was so porous that the molten metal would wick up into the 3D printed object by capillary action. In the end they polished the thing and had a fantastic one-of-a-kind dragon door handle, that worked as a proof of concept.
 
:-O The shrinkage should be relatively constant. I saw similar process in a factory making small mechanical parts (22 years ago). Injection molding was used instead of printing. Big shrinkage in the range of 1/3 or more (as I remember), but parts almost to final dimension with very little post processing.

The shown 316L material is fairly expensive with 150$ for 500 grams.

Three aspects:
1. if sintering is wanted it must be printed with 100% infill.
2. At a density 3 to 4 times of the PLA the 500 gram spool will look quite empty, compared to a 1kg PLA spool; 1/6th roughly.
The 316L material claims quote: "It contains 80.0% - 85.0% metal and has a density of 3.5g/cc." Question does that add up?
Density of 316L is 8 g/m^3 and density of PLA 1.25 g/cm^3 My estimate would be: 0.8*8+0.2*1.25= 6.65 So there must be something wrong.
3. the sintering process requires a fairly expensive oven and possibly some experimenting to get it right.

Interesting options everywhere, but possibly we will not print a snap on wrench any time soon. :cool: Maybe a snap off wrench?
 
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Thanks for that !
I liked the debind/sintering instructions https://thevirtualfoundry.com/debind-sinter/

Sounds like it will make a decent metal part but 7-10% shrinkage seems excesive.

Scott
During sintering of metal powder shrinkage in this magnitude is not unusual. (actually 10% sounds not much)
Voids are removed during the sintering. Pressed green parts look like a solid metal, but can be crumbled.
 
All your carbide inserts are sintered. In that case the carbide is in powder form and pressed at very high pressure into a mold. It is then taken to the sintering oven where it is baked at high temperature and the powder fuses together forming a very strong cutter. A similar process is used for making small parts such as bushings and other small high volume complex parts that need very little handling after sinterred.
 
Other than FM (Freaking Magic), how do they keep a complex part from changing shape as it's sintered? If the metal gets hot enough to fuse, I'd think it could also flow and change shape.
 

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