Molding And Casting

For this assigment, we have to:

- (DONE) Design appropriate objects within the limitations of 3 axis machining.
- (DONE) Demonstrate workflows used in mould design, construction and casting

All the files created for this assigment can be found on the link bellow:


---> DOWNLOAD FILES<---


Have you:

- Explained how you made your files for machining
--> yes
- Shown how you made your mould and cast the parts
--> yes
- Described problems and how you fixed them
--> yes
- Included your design files and ‘hero shot’ photos of the mould and the final object
--> yes


Designing The mold

I wanted to do a double sided fish, so I had to do a mold for both sides of the fish. This are the steps I did for designing the mold:

1. The first thing I did was to measure the size of the wax mold so that I could calculate how big the fish should be so that both sides of the fish fitted in the mold.
2. Once I had the measures, I started to do the sketch of half of one side of the fish.

3. Then, I draw the mold dimensions on the sketch and left a margin to the mold limits. This margins are the internal walls of the wax mold that are going to contain the silicon.

4. Then, I centered the sketched fish inside the sketched dimension and draw circles on the blank parts around the fish.

5. Then, I mirrored the sketch of the circles and the fish and puttted both figures innside the sketched dimensions of the mold.

6. Then, I struded out the sketch of the fish.

And extruded in the paths that represented the separation between the squamas of the fish.

7. After that, I struded out the base of the mold.
And the walls of the mold.

8. Then, I struded out the circles on one side of the mold and extruded in the circles on the other side of the mold.

9. I rounded all the borders of the mold by using the fillet tool.
10. I joined the separate bodies by using the combine tool in modify->combine
11. Finally, I exported out the solid as an stl file.


Making a Wax Mold

I was the last person to make the mold and there were no wax molds to mill. So with the aid of my tutor, I had to do my own wax mold from some milling residuals. This are the steps I did for getting the wax mold:

1. First, we putted all the residuals inside a rectangular baking mold.

2. Then, we putted the baking mold inside a convection oven, so that the residuals melt and made a new wax mold.

3. We setted the temperature to 275 degrees and the time to one hour.
4. We let the oven heat the mold and every 20 minutes, we filled the mold with more wax residuals.


5. Once, the hour was passed, we retired the mold, and let it cool by some hours.


Molding the wax

For millling the wax I used the modela MDX milling machine and a 1/16 inch end mill. the procedure for milling the wax is almost the same than the one used for milling a pcb. This are the steps I did for milling the wax mold:

1. I inserted the end mill in the spindle and adjusted to it.
2. Then, I pasted a double sided tape on the base of the wax mold.


3. After that, I sticked the wax mold to the milling platform.
4. I oppened the fab modules and selected the importing file as STL.
5. Then, I loaded the stl file.

6. Since the end mill I was using was a 1/16 end mill, I chose the option mm 1/8 wax rough, but changed the field diameter to 1.5875 mm.
7. I chose the side -y and clicked on path.

8. Since the wax surface was not uniform and I needed a reference height for milling, I moved the end mill to a point in the wax were the height was minimum (x=60,y=60) and moved it down, by pressing the down button on the machine, until it reached the wax surface.

9. Then I moved the end mil to the initial coordinate of the wax (x=12,y=12)
10. I clicked on make rml, then send it and then begin

11. Once it finished, I changed the end mill to a ball nose 1/16 end mill.
12. I turned on and off the milling machine for reseting the positions.
13. I chose as tool mm, 1/8 wax_finish, but changed the diameter of the tool to 1.5875
14. Since the referenced I used previously was milled, I used as height reference the center wall of the mold, and then moved the end mill to the wax origin position (x=12,y=12)
15. Then I clicked on make path for getting the path of the end mill.

16. And then I clicked on make rml, send it, begin mill and waited until the process finished.




Casting the mold

Once I had the wax positive mold, the next step was to get a silicon negative mold. This is done by pouring silicon in te wax mold. Unfourtunatelly one of the walls of my wax mold was partially milled and fell from the mold, so I replaced this wall by a piece of mdf board I found.

Once I solved this issue, I did the next steps:
1. With the aid of a balance, I mixed 80 mg of silicon with 1.6 mg of silicon catalizer (a proportion of 2% of catalizer per mg of silicone).


2.Then, I mixed both substances until the mixture was uniform and droped the mixture in the wax mold
3. I waited a day until the silicone was dry, and retired the silicon mold.

4. Since, I forgot to do a little path for filling the silicon mold, I had to do it with a cutter.

5. Then, I cutted a pair of MDF board with the same size of my molds for making pressure to each other.
6. I putted the silicon molds between the MDF board and fixed it with tape

7. With the aid of a balance, I mixed 13.2 mg of water and 60mg of cemment (22% of water per mg of cement)

8. Then, by using a syringe I inserted the liquid cement into the silicon mold.


9. Finally, I waited until the cement was solid and opened the mold

This is the final result:


As shown on the video, some details were lost, like the eyes of the fish, in order to fix this, I could have used a mill of a smaller diameter than 1/16 inches.