What We Learned at AMUG 2018 – Part 2

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Computer Aided Technology was lucky enough to participate and attend AMUG 2018 and learn all we could about all the additive manufacturing technologies out there. It was fun week full many different classes, events, and lectures, but my favorite event by far was “Foundry in a Box”.

Preparing to pour molten tin into a 3D printed sand mold at the “Foundry in a Box” event at AMUG 2018

In “Foundry in a Box” we were able to get hands on experience with two different types of casting processes: Sand Casting and Investment Casting.

For traditional sand casting, a special type of sand is compressed into a metal pattern and solidified into a one half of a mold. The process is repeated for the second half of the mold. Molten metal is then poured into the sand mold and set to cool. The sand mold is then separated or broken apart and the solid metal part is extracted to be post processed.

Investment casting is a process that utilizes wax patterns to create a ceramic mold. First a metal injection mold is made. Then a wax is injected into the mold to create the desired pattern. This wax pattern is then repeatedly dipped into a ceramic slurry and solidified until a thick coating of ceramic coats the wax pattern. The ceramic covered wax pattern is then placed in an oven. The oven melts the wax out from inside the ceramic coating. Now the ceramic coating is a hollow mold. Molten metal is then poured into this ceramic mold and set to cool. Once cool, the ceramic is broken off. This leaves just the metal part ready to be post processed.

Now, how was additive manufacturing implemented to help improve these widely used casting methods?

In this case, for sand casting we used 3D printed sand molds! The most expensive part of sand casting can be getting the metal patterns manufactured, and it can take weeks to get even one pattern set made. If the part needs to go through multiple iterations and revisions, then multiple sets of metal patterns must be created. The monetary and time expense in doing that can be a huge strain on any company. 3D printed sand molds allow casters to produce molds without having to create the expensive metal patterns. This allows them to get through the all the revisions quickly and easily. If the part volume is low, it may not even be profitable if manufacturing metal patterns, but the low cost of 3D printing the molds allows lower production volumes to be viable.

For investment casting we had the wax patterns 3D printed. These printed wax patterns are used the same way as the injection molded patterns. Like with sand casting, we cut out the process where expensive metal tooling is manufactured, and we get identical benefits when doing so.

It was a ton of fun learning both of these methods with the help of 3D printing!

 

Cody Doiron
Field Service Engineer
Computer Aided Technology, LLC