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3d Printing aluminum?


I was thinking about 3d printing aluminum and was wondering if you could do something like this. You have a stainless steel air tight cylinder, surrounded with some refreactory, then nichrome wire, then insulating refreactory. The first layer of refractory is to prevent an electric short between the wire and the stainless steel cylinder. Stainless steel so it will take longer to oxidize. You would fill the cylinder with aluminum, close it, turn on the heater, t would heat up the stainelss steel and aluminum and melt the aluminum. Temperature could be regulated. Air would go to a hole in the top of it, the air would be regulated by a solenoid valve and a a pressure release valve. A needle with come out of the bottom, however it would be bent into a upside down U shape and one side would poke out the bottom, this would preven the aluminum from running out when there wasn't pressure. When the solenoid is open, aluminum comes out, when the solenoid is closed the release valve is opened to get rid of any excess pressure and stop the aluminum flow. This would be put in the place of the the traditional extruder, would this work?

I have a research paper on the topic. The apparatus there is essentially an inkjet mechanism, for liquid aluminium. The whole system is in a high vacuum chamber, because oxygen and aluminium have such a high affinity, you have to have zero oxygen there for decent metal deposits.

The other reason for the vacuum is that the system uses electrostatic deflection to bend the ink jet ( a stream of microscopic drops) to deposit metal where its required.

The paper was elegant, but I haven't seen further work by the same guys.

Steve
heathbar641 year ago
why not just attach a mig welding nozzle to a cnc platform and set it up with aluminum wire and appropriate shielding gas.
Stubbe1 year ago
Absolutely no cooling is required. You can print metals directly upon your hand if you want.

Metal spray guys have been doing this for a century.
ARJOON3 years ago
ha you would need more than that. you would need some liquid nitrogen for instant cooling, and also some other stuffs. very costly
snowluck2345 (author)  ARJOON3 years ago
couldn't you also use a refrigeration system and something that has a large thermal mass and doesn't bond to aluminum. Since you say liquid nitrogen I assume it has to be a very cold, so a triple cascade cooling system could be used.
kelseymh3 years ago
Theoretically, a molten metal printer would work, but I'm not sure that your design is practical. A few concerns:

1) Aluminum has a melting point of 933 K; nichrome's melting point is about 1670 K. Generally metals become plastic and deform at temperatures above half their melting point. I'm not sure that you could fabricate a nichrome system to get that hot and still work.

2) Is stainless steel wetting or non-wetting with respect to other metals? If it is wetting, then the aluminum will stick to it rather than flowing through nicely.

3) How quickly would the molten aluminum refreeze? It has to be slow enough that it can flow out the bottom hole onto the developing piece, but fast enough that it sticks where you want it.

These aren't meant to be objections in principle, rather questions of engineering design. So far as I know, most 3D metal printers operate by sintering (heating a metal powder so it welds together), and I suspect there are good reasons for that.
4) Getting the new layer of aluminum to bond with the cold, earlier layer.

This is basically what a rep-rap does with plastic, or a glue gun does.
rickharris3 years ago
The arrangement you describe is used in making bench top casting crucibles - usually for Pewter but I guess Aluminium wouldn't be impossible.

For metals for many reasons casting into mounds made with your CAD/CAM system is much easier.

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