What's new
What's new

3D Printing and casting

sen2two

Aluminum
Joined
May 19, 2010
Location
Orlando, Florida
The main reason I am looking into 3D printing is so I can use the printed model as a template to make cast parts. Not for producing multiple parts or for manufacturing. But mainly parts for myself and my hobby. Often there there times I am designing/machining something and I can not make it the exact way I want because my manual machine is limited in it's abilities.

Can someone please enlighten me on how 3D printed parts can be used for making cast aluminum parts for the at home do-it-yourselfer.
 
I don't know about the "do it at home" caster part - and you can buy an entry level VMC for what a useful 3D printer might cost.

That said - Z-corp sells a machine that's not too pricey ($20K maybe?) and runs a process (among others) called Z-cast. Z-cast produces an actual flask into which molten non-ferrous metals (e.g. aluminum) can be directly poured. I owned a project that used it in the early 2000's and it was very useful - though I've never done it myself.

There are other processes to do this now, and other posters with more direct experience talk about it.
 
Hi sen2two:
You have some options here:

For green sand casting:
The first, and probably most obvious is to use the printer to make a loose pattern, commonly a split pattern if your part has geometry that doesn't lend itself well to just laying it on a mold board to ram up the drag.
You need to respect the constraints of a loose pattern; things like shrinkage, drafts and core prints as needed, and you need to finish the pattern smoothly enough to both meet your cosmetic needs and to make it possible to pull the pattern from the sand.
You need to print or insert pins to align the two halves, and you need to decide how robust you want to make the pattern, depending on how many parts you hope to get off it.

If you need to make respectable numbers of parts, you can print a bunch of patterns and mount them on a plywood board to make a matchplate.
You put the sprue, the runners, the gates the risers or riser pads all on the board, and you make the matchplate so the foundry you choose (if it's not going to be you doing the casting) so the foundry can run it on their more automated line.

For investment casting you have a couple of choices as well.
1) you can make the male master, take off a silicone or vulcanized rubber mold and shoot waxes from that which are then invested and cast.
2) you can learn what you need to use for materials, for investment , and for burnout protocol to invest the 3D print directly; making it the burnout pattern.
3) You can print a female mold directly, use it to mold your patterns in foam, or in wax and invest and cast those.

Whatever you choose; the big benefit of using the 3D printer is to eliminate the effort to make the pattern.

When you make a direct pattern, say in styrene or polycarbonate that can be invested and cast you can be much more cavalier about getting the details right, so long as you can invest it completely and you've sprued vented and risered it properly.
As soon as you have an intermediate process somewhere in the chain, whether it be pulling a pattern from a green sand mold, pulling a pattern from a silicone mold and shooting a wax, or whether you're making the mold directly from the 3D printer, you have to get a lot more anal about the details to get it to work; and if you intend a foundry to cast them for you, you must get everything correct or the foundry will reject your job because you're not worth the hassle.

So in your particular case; for green sand molding, I'd make good quality loose patterns.
Get out the Bondo and the sandpaper when they're printed and make the draft faces super smooth.

If you don't know already, get some books or Google your way to a good knowledge about what a green sand foundry pattern has to look like.
Learn about cores, core boxes, and core prints.
Learn about spruing gating risering and venting.
Learn about split planes and follow boards.

Once you know all that put your 3D printer to work; it's a great tool for stuff like this.

If you hope to investment cast your parts; you have lots more to figure out:
#1 is whether you can do a direct burnout of the 3D print or not.
Many plastics create a lot of toxic shit and a lot of ash when they're burned and are not suitable as burnout patterns.
The four gold standards for burnout materials are wax (best), acrylics (only some kinds), styrenes, and polycarbonates.
Those are the ones I know of; there may well be lots of others.
If your printer can print one of those materials you've got it made; if not, you have to make intermediate molds, preferably in silicone or vulcanized rubber, and shoot waxes into them with a jeweler's wax injector.
Making the molds properly is a whole other topic, and it's a fairly big one.

Oh yeah; not to be deliberately contrary, Bryan, but for low tolerance stuff like casting patterns, any one of the cheap printers on the market these days can be pressed into service very successfully.
The reasons I say this are as follows:

1) You have to finish the patterns anyway, so the better resolution of a better printer isn't worth much for this application.
Even the very best printer isn't good enough for draft faces.

2) If you're hobbying, you don't need to care how long it takes to print the pattern; if you're industrial you'll have proper patterns made anyway.

3) The tinkering is part of the fun; and fiddling with a low end printer gives a lot of guys a lot of satisfaction.
Cheers

Marcus
Implant Mechanix – Design & Innovation - home
Vancouver Wire EDM -- Wire EDM Machining
 
@Implex - sure - if you mean "3d print an almost pattern, fix it up, then use it to make a sand flask" - most any 3d printer that prints big enough could work for that.

And I suppose most any printer will be accurate enough that if it can print "invesment" you can make investment castings easily as well.

The claim to fame of the z-corp/z-cast, and various other processes, is that they print *the flask* (not a pattern, but the actual flask) so you take the output off the machine, put it on a support, and pour metal into it. Gates, runners, shrink rules, all of that have to be in the model you find to the printer. No other work was done on the flask. My venture used it in a commercial process (racecar engines.)

So, I don't find your notes contrarian, rather, I agree with them.
 
If you go to 01 Feb 2013 in this blog

US Moto2 Bike

and work forward from there you can see an example of 3D printed parts being used to make 4130 steel investment casting patterns (though a silicone mold was pulled off of them and waxes made from the mold). Note the mention that a lot of hand finishing was needed to bring the printed parts up to snuff before the molds were made from them.

There are companies that can 3D print the sand molds but I have no idea of how expensive that process is. There are some interesting videos on YouTube of that process. From what I've read they can print sand moldss that you probably couldn't make from traditional patterns.

cheers,
Michael
 
The main reason I am looking into 3D printing is so I can use the printed model as a template to make cast parts. Not for producing multiple parts or for manufacturing. But mainly parts for myself and my hobby. Often there there times I am designing/machining something and I can not make it the exact way I want because my manual machine is limited in it's abilities.

Can someone please enlighten me on how 3D printed parts can be used for making cast aluminum parts for the at home do-it-yourselfer.


If you check out this thread there is a person who works for a company who prints molds and can do castings for you. If you follow up with this I am sure they can help you make the parts you want.

http://www.practicalmachinist.com/v...rinting-new/3d-printing-sand-castings-278277/

Charles
 








 
Back
Top