13. Molding¶
Overview¶
This weeks goal was to create a mold with out any production signs and use it to cast parts. I decided to use a 3D printed gear I created as the model that I will create the mold off of. I decided to work with my group mate Andrew Puky as he had create a slightly different but still similar gear. The gears were both early concepts of our machine week projects gears that we used to move our machine side to side. I decided to crate a soft mold using a silicone mixture of part A and Part B. This way I could create many hard casts that could be very useful for a future project.
Group work¶
Click this link to take you to my group work site for tis week. My partners were Andrew Puky and Zaina Gibrine and together we created and tested multiple kinds of molds and casts for our group work week. I found and wrote the specific details and specifics for each kind of material we used.
Molding Process¶
I used Mold Star Series Platinum Silicone Rubber Part A and B with a 1 to 1 ratio to create the mold for this project. Click here for my fusion 360 file that I used.
Part A
Part B
a. We removed the Lids from both buckets and stirred the mixture thoroughly
b. I poured part A and part B into separate smaller red cups with the exact same volume
Pouring
Pouring
c. I hot glued my part down into a clean popcorn bucket where I would later add both substances
d. I took each red cup and poured it into the popcorn bucket at the same time.
e. I made sure to fill the bucket completely above the top of a gears to ensure a good mold.
f. Next I waited 12 hours and when I came back this was the finished product:
Casting¶
Next I used the TotalBoat TableTop Epoxy hard resin as the casting material where I would pour it into my silicon mold of my gear.
Casting Data Sheet - TotalBoat TableTop Epoxy¶
| Property | TotalBoat TableTop Epoxy |
|---|---|
| Type of Material | Epoxy resin and hardener |
| Health Hazards | May cause skin or eye irritation; can cause breathing discomfort |
| Precautions | Wear gloves, safety goggles, and avoid spilling |
| First Aid - Skin | Wash completley with soap and water; remove contaminated anything |
| First Aid - Eyes | Rinse carefully with water for 15 minutes, seek medical attention |
| First Aid - Inhalation | Move to fresh and better air immediately, seek medical attention |
| Flammability | Combustible, avoid open flames and high heat sources |
| Storage | Store tightly closed in an average temperature, dry place (60–90°F) away from heat |
| Disposal | Do what your area says to with these kinds of chemicals |
More Notes¶
- Mix Ratio: 1:1 by volume (resin to hardener)
- Working Time: Around 20 minutes at 70°F
- Cure Time: 16–20 hours at 70°F
- Maximum Pour Depth per Layer: 1/8” to 1/4”
For complete documentation and safety guidelines go to the TotalBoat TableTop Epoxy Product Page.
Casting Process¶
a. First I poured 100 ml of part A into a plastic cup
b. Then poured 100 ml of part b into a different plastic cup
c. I poured then both into the same cup. Puky and I mixed the two parts together until the opaque solution seemed more clear.
Stirring
More Stirring.
d. Then we poured our solution into our rubber molds
e. Finally we used the heat gun to get rid of any extra air bubbles that were floating around in the solution.
f. we left it to sit for around 3 days to solidify then carefully removed both molds.
Still encased
Removing the cast
The final product
Post Process¶
Painting¶
Because of how I made my mold and the material I used with it. It was necessary for me to smooth the layer lines out for the cast completely. Cooper Cumbus assisted me in understanding how to do this.
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To smooth out my design I used the epoxy coating material: XTC-3D
Data Sheet¶
| Property | XTC-3D |
|---|---|
| Type of Material | Epoxy coating for 3D prints |
| Mix Ratio | 2A:1B by volume |
| Pot Life | 10 minutes |
| Cure Time | 2-4 hours at room temperature |
| Shore Hardness | 80D (approximate) |
| Viscosity (cps) | 1,000–1,500 cps |
| Color | Clear (can be tinted) |
| Useful Temperature Range | -30°F to 300°F (-34°C to 149°C) |
| Specific Gravity (g/cc) | 1.1 |
The instructions said to used 2 parts of A and 1 part of B and mix the solution very hard to create the coating material.
After I was done mixing and painting heres what my molds looked like:
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Reflection¶
I learned the importance of carefully measuring the amounts of solutions I needed as to not accidentally ruin the solution for either the mold or the cast. I also learned how to preform good lab safety with harmful chemicals all around me. I also need to have a covering on our table to prevent accidental spillage, wear strong and protective plastic gloves, and work with another person in such an environment by communicating efficiently. I now understand that molding and casting is a very effective way of creating the same part multiple times very quickly and very precisely.