how many people here are 3Dprinting molds for casting?

[Metzindustries]

I got 3D printers and access to laser and water jet, however machining is getting pretty expensive for me. Lately I am needing some metal parts made and I am considering printing the part, and making a silicone rubber mold to cast tin or a alloy of tin.

I have dealt with large companies locally with sand casting but they do not do 3d printed molds yet. So i am wondering how common it is outside of the Philippines?

Is the lost PLA method viable for investment casting from a pros point of view?

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[Mike 1948]

Search the web for DMLS , direct metal laser sintering. It may work for you if the part is not to big.

Mike

[awerby]

That would work, but only if cost is no object. Those DMLS machines are quite expensive at this point, and anyone who's invested in one will be wanting to make that money back - or at least break even.

The idea of printing positive models, making silicone molds, and casting metal into the molds could work, but there are some details to be aware of:

The output of most inexpensive 3D printers is a bit rough. You'll need to spend time cleaning up any stubs from supports, filling and sanding to eliminate striations from the printing process, or using acetone to smooth the surfaces.

Not just any silicone rubber will work; you need the kind that's formulated for high-heat applications. And you need to use the 2-component RTV (room temperature vulcanizing) rubber, not the kind that requires a heat press, since that would melt your original parts.

The metals you can use this way need to be pourable at no more than about 500 degrees F; that means you're limited to alloys of tin, lead, zinc and a few other low-melting metals. None of them are particularly strong, so make sure they don't need to be for your application.

Getting the metals into the molds might be an issue, if the parts are small or have thin sections. People who do this kind of casting professionally use centrifugal force to push the metal into the mold cavities with enough force to get all the details. Look up "spin-casting" for more information on the process.

As for "lost PLA" the results I've seen aren't particularly impressive. The material doesn't burn away completely, but leaves a bit of ash that leaves voids in the metal parts. And the surfaces aren't any better than the original models, which tend to be rather poor, showing each individual line left between each layer. You might be able to eliminate those with a wax dip, but that would tend to obscure important details. If you want to do investment casting, I'd say either start with a machined part and take a mold of it which you can use to produce multiple castings in wax, or take the mold from your cleaned-up 3D print.

[kreutz]

Take a look at the following links:
Metal Casting with Your 3D Printer | MAKE

Casting Wax 3D Printing Material Information - Shapeways

kreutz

[Metzindustries]

I had assumed people already seen the videos linked to in the other posts. It is just that there is such a lack of info online I put a shout out here.

I build my own printers and can get 50 micron resolution, and wet sanding is always a finishing optin at higher resolutions. So mold creation is not the issue.

With silicone, I have used red rtv gasket silicone up to 605C with NiChrome heaters.

It is just curiosity as to if people are using this method commercially? Aside from jewelers and pewter guys on one end and the guys making sand cast molds with large inkjet resin printers, there seems that there's no in between usage.