Tethon 3D launches ceramic SLA / DLP Resin “Castalite”

General Discussion
1

Tethon 3D is launching a new photo-curing ceramic polymer resin called Castalite. It is suitable for 3D printing ceramic shell molds ready to accept liquid metals.

This product is a new UV curable ceramic resin. It’s curable with UV wavelengths between 350 – 405 nM. Its uses are 3D printing ceramic molds for metal investment casting. This material is for use in SLA and DLP printers.

The company believes that Castalite will offer higher quality prints for customers. Molds can be 3D printed directly in the material which then undergoes furnace firing. Finally, the resulting ceramic shell can accept liquid metals.

I dont do castings it looks to complex. but will this resin work to create molds in one step so that all i need to do is pour in hot metal?? after i fire it .

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Should be good for low temp white metal casting as that is about 450 degrees. I’ve done a lot of that with silicone molds. Be interesting to try it.

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You can make molds from Castalite. The mold will need to go through a burn out process before casting. The burn out process is similar to melting out the wax in an investment mold or a ceramic shell mold. Here is some more information on how to use Castalite. http://tethon3d.com/wp-content/uploads/Castalite-Guideline-1.pdf

4

The material will cast well for materials at 450 degrees. The mold should still go through a burn out process before casting. The mold will combust if hot materials are casted directly into it with out going through the burn out process. Castalite can cast to at least 2300*F.

5

how much does it shrink during firing?
And what temperature does it need to reach in firing to handle 1900f?

6

The final shrinkage will depend on the final burn out temperature. The hotter the more shrinakage you will see. Adding supports around the model will help keep the parts uniformity during burn out. You can expect to see between 10 - 15% shrinkage. The minimum temperature needed is 2100*F to make the molds hard enough to grab onto.

7

Won’t you need to fire that mold first prior to using it for casting? Thinking that firing it first will stabilize the mold so it doesn’t shrink when pouring your metal into it. Correct?

8

firing the shell will cause the shell to shrink, so you’re pouring metal into a shell mold that is already smaller than the original Print.
Its is essential to know the total compounded shrinkage you will see between model dimensions and final metal part so that you can scale to compensate.

10 to 15% is pretty severe… and not a very precise spec. It would be great if tethon could publish a chart showing a more accurate projection of shinkage at different cone temperatures.

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Isn’t that pretty standard for firing ceramics ? I’m by no means an expert but I’ve heard similar numbers from industry specialists.

Agreed on the fact that precise shrink value (up to the 10th or % at least) for a given firing method is necessary and should be provided by the manufacturer. Otherwise it’s just trial and error for the consumer and a huge loss of time, money and reliability.

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If you are firing porcelain slipware… sure, 12 or 15 % shrinkage is common… but this is a Ceramic SHELL mold for casting bronze or aluminum or steel.
In standard lost wax bronze casting, for example, the total cumulative shrinkage of the silicone mold, the wax cast in the silicone mold, the ceramic shell that is slurried over the wax and fired, and the final bronze pour is only 4%

In jewelry casting, shrinkage from pattern to final gold is less than 2%.

To cast metal parts with predictable dimensions, we would need to know the total shrinkage to a predictable accuracy.

15% is a very high shrinkage…

11

So you’re printing your shell, then fire it. It will shrink 10-20%. Then you pour the material into the mold and while cooling the metal/mold also shrinks.

Are we talking about the first shrink or the second one ? I was only talking about the ceramic firing operation, not the actual casting. And I think @Tethon3D was talking about the same thing as me, but maybe I misunderstood.

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My question is will the shell shrink when the metal is poured into it? If so then the shell might shatter, right?

As far as dimensional accuracy I think JohnHue is correct that it seems like a pretty standard amount of shrinkage.

If you need more accuracy for mechanical parts then lost wax might be a better approach. This seems more intended for small sculptures and jewelry pieces.

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To clarify some of the concerns about shrinkage. We give a range because there are many things that can effect the final shrinake of a part. The hotter Castalite is sintered the more it will shrink. Minor changes based on the machine and settings that are used to make the mold can effect the shrinkage as well. The method for each part will need to be worked out to meet the standards that are desired.

When making a mold for Castalite it is recommended to model in supports for printing and sintering directly into the mold. This allows for the most amount of control to take place in during shrinkage.

@JohnHue you are correct, the Castalite needs to be heated up first to burn out the mold to make it a ceramic shell. Then as the mold cools you can pour the hot metal into the mold. You can also cool the mold all the way to room temperature and then reheat the hold before casting.

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Allow me to correct my statement : 10-20% of shrinkage in ceramic seemed standard to me but not a 10% range of accuracy. I am expecting to see a document with information like that :

if fired at xxxx°C for X amont of time following this specific temperature curve, you will get 14.7% of shrinkage with a tolerance or ±.2%

@Tethon3D will you be able to provide such information in the near future ?

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No one answered that if you Don’t fire it first do you risk cracking the mold?

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The material is a ceramic filler in a photopolymer vehicle.

This allows you to print a shape of ceramic… but it’s not unlike greenware in ceramic slip casting…
A fragile structure of dried mud.

Ceramic only becomes the porcelain or kaolin like material you associate with the term when it is fired at temperatures that essentially FUSE the clay particles so they fuse into a glass like structure.

This is what makes ceramics able to take the very high temperatures they can withstand.

In casting metal… you have 4 basic options… you can mold in sand- which as quartz/feldspar can already take high temperatures… you can mold in neoprene, or platinum silicones…but those materials can only take relative low melting point metals like pot metal, pewter and such. You can do a lost wax mold in a foundry investment- which is a plaster like material that is filled with high temperature resistant fillers… or you can take a wax casting and DIP it in a vat of a ceramic slurry, repeatedly, building up a thin “shell” of ceramic clay (filled with sand or other refractory agents)… let the shell dry- then Bisque fire the SHELL- which burns out the wax and pour the hot metal into the shell mold.

Because the shell is only bisque fired… it remains pourous- allowing the gasses in the metal to vent out directly thru the shell wall, and after it cools you literally jackhammer the shell off the metal casting.

This medium is meant to allow you to PRINT a shell directly, without dipping it and drying it laboriously and enable you to print more complex shell voids than can reasonably be made using wax masters.

However… the ceramic shell process as currently used has a VERY LOW shrinkage factor.
1.5- 2%… which compounds with the metal and wax shrinkage for a total dimension change of 4% from original master- to final metal casting.

In knowing this factor- I can sculpt a master exactly 4% overscale and know it will shrink to my target dimensions. This is critical in, for example, fitting a cast metal part to, say, a cast Concrete structure, because the concrete is NOT gonna shrink at all.

Or in this case… fitting a cast metal part to existing parts of known dimensions.

In normal ceramics, the shrinkage can be very high, especially in the porcelains, because they are fired so hot.
Someone throwing a vase or coffee cup knows it’s gonna shrink a lot.

But in ceramic shells used in foundry operations, the ceramic slurry is heavily filled and alternated with layers of sand… it just doesn’t shrink nearly as much.

In jewelry casting, refractory investments do not shink at all, rather they every so slightly expand… and a ring master needs only be 1.5 - 2% bigger than your target ring size.

But I can not reasonably cast a custom ring to the size I want if I can’t nail down the shrinkage I am going to get to within a half percent or so.

I think a schedule of settings and conditions, including a curing and a firing schedule should be compiled so that folks wanting to use this media can design their patterns with confidence.

1 Like
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I do quite a bit with delft clay (similar to sand), silicone molds for white metals and organic rubber molds as well as silicone molds of various durometers for resin casating. I just wasn’t all that familiar that particular material. I wasn’t sure if it was as forgiving as you say thought it needed to be fired first.

Next question… Can it be printed on a Form1+? Does anyone have settings for it?

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@KenCitron yes the mold will crack if you do not fire it first. It is not recommended to do this. The burn out or firing process is required before casting.

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That’s what I thought. I had my doubts that the metal and investment would have the same expansion rates.

Is it available for the Form1+?

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will this material print at 25 nm? for fine jewelry detailing?