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Sand cast aluminum, from pla/abs

Posted by Bronston 
Sand cast aluminum, from pla/abs
May 24, 2011 05:50AM
I'm curious, has anyone attempted any sort of sand casting with aluminum from a printed plastic model. If you are unaware of how this process works essentially you bury a model of what you want cast in aluminum in sand then pour molten metal into the mold which burns out and replaces the original structure, usually done with Styrofoam or something of that sort, but I would like to find out if one of the extrudable options would work, thus allowing some extremely complex objects cast in aluminum, in my backyard. If I don't hear anything, I will try it and see what happens. I apologize if this has already been discussed, I couldn't find it.

Re: Sand cast aluminum, from pla/abs
May 24, 2011 06:02AM
Hi Bronston

I had thought about using this approach too, but don't have any spare time to try it.

I would think that making the insides as light as possible would help e.g. 10 - 20 percent fill. Just enough plastic to support the walls. This would mean far less plastic to burn off during the pour.

Re: Sand cast aluminum, from pla/abs
May 24, 2011 08:10AM
I think ABS is too dense to give ideal results, although it should work to some degree. I don't think you need a great deal of internal structure at all. Just enough to keep the sand in it's shape until the metal makes its way in.
Re: Sand cast aluminum, from pla/abs
May 24, 2011 08:22AM
please do post your results. This is one of my current projects as well:

Re: Sand cast aluminum, from pla/abs
May 26, 2011 01:18PM
You're best off doing an investment casting type of system with a burnout of the ABS in a ceramic shell - I don't think doing a 'loast foam' type of casting with ABS rather than foam will work terribly well (all the density will be at the surface of the part, so you won't be able to capture any detail, and the aluminum will be all crudded with burnt plastic on the surfaces).

You can get some excellent results with regular investment cast techniques - one of the fellows in my aluminum casting class last year had used plain old plaster of paris around a few Lego minifigs and then did the burnout in a kiln. After pouring the aluminum and breaking away the mold, he was left with a surprisingly good level of detail in the casting. You should be able to do even better with proper investment mold materials.

Re: Sand cast aluminum, from pla/abs
May 28, 2011 02:13PM
it wouldn't be all that difficult to make a simple mold of your print and make wax castings from that though.. that's the way i would go if i wanted to do any metal casting from a print
Re: Sand cast aluminum, from pla/abs
May 30, 2011 05:29PM
I considered also to make some experience about sand casted aluminium.

You may find some encouraging infos here smiling smiley
[diamondage.co.nz] ("Used for making mould cores as it will completely vapourise on strong heating")

I have a friend that make these experience with some PLA wastes from my mendel, they first heat the mould to eliminate the plastic, and then pour the metal (otherwise it will explode if I understood)
Re: Sand cast aluminum, from pla/abs
January 24, 2012 04:46PM
I'm spinning a idea in my head about making silver and gold jewelry... i think "under pressure"-casting could work with ABS and PLA, print out necklace, insert into casting tree.
Pour plaster around casting tree and bake it in a high heat oven for a night until all plastic has burned out and pressurise the whole thing + pour precious metal into cavity which has formed after plastic burned away and you should now have something nice smiling smiley

I'v done this few times with laser printed parts but i'm looking for more price efficient option.
Re: Sand cast aluminum, from pla/abs
January 24, 2012 07:16PM
If I ever get my printer to work, I'd like to try and use water soluble PVA filament and print something with that. Dip it in whatever you have to build up a shell, then put it in water to dissolve the PVA. Dry the shell and pour.

Wikisi, yeah that should work.

Also you can make chocolate molds by brushing lab/med grade latex/silicon around your printed prat so you make easy molds and same goes with dublicating your print into candle wax so you can cast them easily.
Re: Sand cast aluminum, from pla/abs
March 13, 2012 12:41PM
Sadly I'll never know, I've all but given up on this printer after dumping nearly $2500 into the thing and still not having a single usable print, I'm pretty sure all you guys that have a functional printer are using magic or something winking smiley. Last straw was getting in a new stepper driver and having it fry cause one of the motor coils shorted out while the printer was just sitting there for the prior month. Anyway, glad to see this discussion is still going, hope to see more on this topic, I entered a sweepstakes to win a 3d printer and I'm pretty sure based on no evidence that I will. Then I will reenter this discussion proper.
Re: Sand cast aluminum, from pla/abs
March 13, 2012 08:12PM
natural PLA is supposed to burn away without leaving any residue. I'm keen to see if it works well for lost foam type casting.
Re: Sand cast aluminum, from pla/abs
March 14, 2012 03:18AM
I have heard that PLA works good for lost wax casting but I have not tried it yet.

www.Robosprout.com RepRap Mendel parts and accessories.
Message if there is anything you need...I have more than what is listed on my site.
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Re: Sand cast aluminum, from pla/abs
March 14, 2012 12:50PM
Site3 makerspace in Toronto tried it. I'm not sure if they were using PLA or ABS.

Here is a link to a couple of photos:

Edited 1 time(s). Last edit at 03/14/2012 12:51PM by Karl_Williams.
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