kori.seiki
Posts: 7
Joined: July 18th, 2007, 9:40 pm
I'd like to get a vessel cast in aluminum, but would like some advice;

I've never done an investment cast - I though it was like lost wax casting - can anyone explain the steps?

i have a CAD file to make an SLA part; can you use an actual SLA part for investment casting? Does the melted resin mess up the mold?

how good are the surfaces once the part is complete?

I thought about sand casting, but I fear the surfaces will require a lot of benching to get the smooth - chromelike surface I desire for this part - Will investment casting get me any closer to a chromelike polished surface than sand casting?

Any ideas or advice? Thank you

July 19th, 2007, 8:38 am

User avatar
dawolfman666
full self-realization
full self-realization
Posts: 759
Joined: January 10th, 2004, 8:21 am
Location: London
I'm no metal casting expert, but I know you can do an investment cast straight from a rapid prototype....not a SLA though. The finish from the investment casting wont be perfect and will need a bit of post work. You also need to watch your tolerances to make sure your mating parts will still fit. Castings shrink as well....so your best bet for more info would be to go speak to a metal casting shop or a RP place with metal casting contacts and I'm sure they will be able to give you far more info.

July 19th, 2007, 8:41 am

User avatar
dawolfman666
full self-realization
full self-realization
Posts: 759
Joined: January 10th, 2004, 8:21 am
Location: London
also....take a look here on the investment cast process,

http://en.wikipedia.org/wiki/Casting
http://en.wikipedia.org/wiki/Investment_Casting

...as I think you have missed the fact that your 'pattern' and 'ceramic mould' gets lost every time you make a casting. So if you need more castings you make more 'patterns' from separate mould

July 19th, 2007, 9:21 am

User avatar
IDiot
full self-realization
full self-realization
Posts: 1223
Joined: January 6th, 2004, 5:15 am
Location: theZoo
sounds like you're looking to do a one off piece right?

You can do investment casting with a piece from an SLA, FDM, 3DP or similar rapid prototype machines, but different machine at different places are going to use different base materials based on their needs. They also make some base materials specifically for casting.

The surface quality with this will however be somewhat limited by the fidelity of the machine, but rather than cast and work the Aluminum to achieve a better surface, why not sand / finish the rapid prototype part? This may be complicated by your base material, but this is pretty common. If you go this route, you may want to scale the form up just a little bit prior to rapid prototyping to adjust for the little bit of material you will be taking away.

July 19th, 2007, 9:56 am

User avatar
Scott Bennett
full self-realization
full self-realization
Posts: 826
Joined: March 3rd, 2005, 5:39 pm
Location: Denver
If you want a mirrorlike finish, you'll need to polish it no matter what you do. Unless you have a very good sand caster, you're probably going to get some small surface voids here and there which might be a problem if you really need a mirror smooth finish. If this is a one off or short run, investment casting from an RP part is probably going to be the best bet. As IDiot said, there are a number of ways to get there- whatever casting shop you choose will probably have a process they prefer. Some of the materials melt/burn out more cleanly than others.

July 19th, 2007, 8:54 pm

kori.seiki
Posts: 7
Joined: July 18th, 2007, 9:40 pm
Thank you very much for sharing this knowledge - In regards to the rapid prototype part, can I use an ABS prototype in such a cast? Will the melted ABS interfere with the molten aluminum in any way?

July 20th, 2007, 10:32 am

User avatar
IDiot
full self-realization
full self-realization
Posts: 1223
Joined: January 6th, 2004, 5:15 am
Location: theZoo
really not sure if ABS would be a suitable material for an investment, it is definitely not one of the the base materials I was referring to that was made specifically for investment casting = ]

you may have to break down and do a test, you could use something you already have made of ABS with a similar wall thickness (and ideally) size to your design, this way you can see if it works before you INVEST (sorry) any time in prototyping.

July 20th, 2007, 11:16 am

User avatar
Scott Bennett
full self-realization
full self-realization
Posts: 826
Joined: March 3rd, 2005, 5:39 pm
Location: Denver
Stratasys FDM machines use ABS material, and those can be used for investment casting. But again, you're going to want to find a casting shop that has done this before. Stratasys (or whatever machine you're using) can probably give you some referrals. Also, FDM surface quality is pretty far from mirrorlike- you'll want to smooth it out as much as possible before casting. It's a lot easier to sand ABS than aluminum.

July 20th, 2007, 11:27 am

User avatar
dawolfman666
full self-realization
full self-realization
Posts: 759
Joined: January 10th, 2004, 8:21 am
Location: London
CRDM are a UK company who can arrange castings from RP files. Take a look over here

http://www.crdm.co.uk/services_rm_investment.htm

They mention Castform or thermojet Wax Patterns

http://www.3dsystems.com/products/dataf ... -A4_UK.pdf

Quickcast

July 20th, 2007, 12:13 pm

User avatar
van_ID
step four
step four
Posts: 296
Joined: July 3rd, 2005, 9:55 pm
Location: Vancouver, Canada
If you're in the US you might want to contact these guys:

http://www.moellerdesign.com/quickcast.htm#

They are a prototype vendror based in Seattle and offer a service called Quickcast.

The above link should get you to their Quickcast information page. Also check out the gallery for some pics. Looks like they may have used Quickcast to produce the Salt Lake Olympic Torch.

July 20th, 2007, 1:08 pm

User avatar
jon_winebrenner
Moderator
Moderator
Posts: 3144
Joined: October 26th, 2004, 10:56 am
Coroflot: 44466
Location: Vancouver, BC
Just an FYI, my experience with Moeller has been crap.

July 20th, 2007, 3:09 pm

User avatar
robertcj
step three
step three
Posts: 149
Joined: March 5th, 2007, 8:21 pm
I've seen people get some great finishes with sand, espeically if the part isn't too intricate, so I wouldn't rule it out. And mabye the time and money you save with prototyping makes up for the work at the end.

casting aluminium

July 23rd, 2007, 10:14 am

User avatar
jGray
step four
step four
Posts: 468
Joined: April 20th, 2007, 4:30 pm
Location: Seattle
visited moeller a couple weeks ago on a tour. I've never worked with them however, but heard some scary things. heres the steez on their quickcast...
its a lighter RP part that has a honeycomblike interior... allows the burnout to properly occur and is cheaper than regular SLA part. This process is typically used for HIGH tolerance parts to be cast in Titanium for like aircraft stuff. probably not the right process for a vessel.... unless it sounds like it is to you.

i have done some sand casting of aluminum and it's probably a good way to go, like everybody else has said, depending on the time you're willing to put into the part after the casting is complete.

you can, however use an RP part as a pattern for sand casting.......
- jg

July 23rd, 2007, 11:09 am

kori.seiki
Posts: 7
Joined: July 18th, 2007, 9:40 pm
Great information!

I may still contact Moeller - I'd like to ultimately try a small run of vessels and the less work I have to to postcast, the better.

With the vessel, the tolerances are not really crucial, so I guess I have some flexibility with which direction to go.

Thank you all!
User avatar
ralphzoontjens
full self-realization
full self-realization
Posts: 855
Joined: February 3rd, 2010, 10:20 am
Coroflot: 76078
Location: Tilburg, the Netherlands
Hi, any chance you will let us know how it worked out?

I am looking to investment cast a part myself and am wondering what the restrictions are for the wax master pattern.

- Can it be designed like any injection molded polymer or are there specific requirements (wall thickness, draft, sliders, split mold etc.)
- Can threads be achieved with good tolerances, are there any tricks do achieve that? Because the standard tolerance mentioned for a cap nearing 2" diameter is +/- 0.35mm and that is far too much.
http://www.id-z.one
IDZone - Product Design || Visualisation || 3D Printing
Reply