10. Molding and casting¶
This week I learned about molding and casting.
Group Assignment¶
We have four molding and casting materials at our lab.
- OOMOO™ 30 Silicone Rubber-Tin Cure
- Ecoflex™ 00-30 Silicone Rubber-Tin Cure
- SORTA-Clear™ 18 Silicone Rubber-Platinum Cure
- Smooth-Cast® 305 Liquid Plastic
The technical & safety data sheets for these materials are below
While skimming through the safety data sheets, I found interesting and important information regarding what to do in case of fire, as shown below. I think this is quite important because it prevents using unsuitable materials or methods for fire fighting.
Test Mold & Cast¶
We wanted to make a test mold and cast to better understand the process. So, we started by checking the available wax sizes at our lab.
Then, we moved to the CNC machine to mill the mold.
Afterwards, we went back to the technical data sheet of SORTA-Clear™ 18 silicone rubbers because we wanted to use this material for the cast. We followed the suggested procedure in the data sheet for mixing.
Finally, we got our mold!
Individual Assignment¶
Design¶
I started by designing the mold of Fusion 360. I first sketched the shape I wanted which is the letter “Z”. Then, I extruded the sketch, and added a taper angle of 5 degrees to make it easier to remove the cast in the end.
Afterwards, I designed the wax mold we have with right dimensions. Then, I subtracted the “Z” body from the wax body. Finally, I filleted all sharp edges.
CAM¶
In order to prepare the milling CAM, I moved to the “Manufacture” workspace. I first created a new setup.
Then, I chose the following settings. What I liked about Fusion 360 is that it automatically detected the stock size!
Then from 3D I chose adaptive clearing to start with the roughing job. The first thing I modified is the tool. I chose it to be 1/8” flat endmill. Then it is important to choose the chain around your mold in the geometry section. Finally, you need to fine-tune other parameters based on the machine you have.
After the tool was generated, I moved to simulation to check that the process is fine. Everything looked fine.
Then for finishing, I used a Ramp tool. The process is very similar to the one followed for the adaptive clearing. I first chose the tool to be Ramp. Unlike the adaptive clearing process, I used a *1/8” flat endmill*.
After the tool was generated, I moved to simulation to check that the process is fine. Everything looked fine.
Finally, I exported the NC file. I first went to Actions –> Post process. Then, I chose the machine to be Shopbot and finally I posted the file to my desktop.
Milling¶
I first fixed the wax stock to the bed. Then, I attached the roughing endmill. Afterwards, I adjusted the zero x,y, and Z and run the machine.
Silicone Mold¶
I used SORTA-Clear 18 to make the silicone mold. I started by getting back to the technical data sheet to find the mixing guidelines. I found out that the required ratio is 10A:1B.
Then, I poured the mixture into the wax stock.
Here is how it looked
After waiting for a whole day, here is the final result
Casting the Resin¶
I used Erco resin for the cast.
Hero Shot¶
Finally, here is my final product!
You may use vacuum to make the results better (I.e. less bubbles).