13. Molding and Casting: Cooper Cumbus, Amalia Bordoloi, Elle Hahn¶
Group Assignment¶
Safety Data Sheets (SDS) - Elle Hahn¶
- Review SDS for each molding and casting material.
Test Casts - Cooper Cumbus¶
- Make test casts with each material.
- Record mixing ratio, cure time, texture, and shrinkage.
Printing vs. Milling Molds - Amalia Bordoloi¶
- 3D Printing: Good for complex shapes, but slower and can have surface issues.
- Milling: Faster, smoother finish, but limited to simpler shapes.
Compare accuracy, time, material cost, and finish quality.
Saftey Sheets¶
These are the data sheets for the two casting materials we chose to compare this week.
Clear Amber¶
| Property | PMC™-746 Clear Amber |
|---|---|
| Type of Material | Urethane rubber |
| Mix Ratio | 1A:1B by volume (100A:90B by weight) |
| Pot Life | ~20 minutes at 73°F (23°C) |
| Cure Time | 16–24 hours at room temperature |
| Shore Hardness | 60A |
| Viscosity (cps) | 3,000 cps (mixed) |
| Color | Clear amber |
| Useful Temperature Range | -65°F to 180°F (-53°C to 82°C) |
| Specific Gravity (g/cc) | ~1.04 |
| Tensile Strength (psi) | ~500 psi |
| Elongation at Break (%) | ~200% |
| Flexural Strength (psi) | Not specified |
| Compressive Strength (psi) | Not specified |
| Heat Deflection Temp. | Not specified |
Smooth-Sil 940¶
| Property | Smooth-Sil™ 940 |
|---|---|
| Type of Material | Platinum-cure silicone rubber |
| Mix Ratio | 1A:1B by volume |
| Pot Life | 30 minutes at 73°F (23°C) |
| Cure Time | 24 hours at room temperature |
| Shore Hardness | 40A |
| Viscosity (cps) | 30,000 cps (mixed) |
| Color | Translucent |
| Useful Temperature Range | -65°F to 400°F (-53°C to 204°C) |
| Specific Gravity (g/cc) | \~1.12 |
| Tensile Strength (psi) | 575 psi |
| Elongation at Break (%) | 400% |
| Flexural Strength (psi) | Not specified |
| Compressive Strength (psi) | Not specified |
| Heat Deflection Temp. | Not specified |
Testing Different Casts - Cooper Cumbus¶
On the left is the Clear Amber material and on the right is the Smooth-Sil 940. I think that the clear amber looks better since I double checked the mesurments and wasnt using materials that had been left out in the open for a long period of time
Comparing A Milled Mold to a Printed one - Amalia Bordoloi¶
Up until this point, our group had all made 3D printed molds so we just made a new mold for a wax to test with a different material. I made a duck mold based off this picture
Heres the final result of the milling:
Heres the process I went through while making it:
First I sprayed the mold to make it non stick
Then I mixed the two parts of the amber silicon together
Finally I poured the mix into the mold
The next day, this is what the cast looked like:
And heres what it looked like next to the 3d mold cast of the same material:
While the milled mold gave a smoother result compared to the 3d printed mold, it is easier and quicker to make and print a 3d mold. This is becuase you do not need to watch the mold be made with the 3d printer while I needed to watch a 40 minute mill for the wax mold.