Molding and Casting

SDS Review and Test Parts

Safety Data Sheets
- OOMOO 30
- Machining wax
Comments
- Most of the materials we used were perfectly safe, but a couple such as ___ were listed as hazards and required proper ventilation

3D Printed Mold
- FDM
  - PLA often considered unsuitable for molding due to coarse layer lines and poor heat resistance for wax coating. However Prusa printer offers an ironing process that can significantly enhance surface smoothness. While the process is useful on flat surfaces, it has marginal effect on curved surfaces. Testing results on 2cm disc:
    - Top left: Monotonic line infill - Baseline
    - Top right: Concentric infill - Cleaner, faster
    - Bottom left: Ironing: 0.15mm spacing, 15% flow - Good improvement
    - Bottom right: Ironing: 0.1mm spacing, 10% flow - Best surface finish
    By combining ironing process with extremely thin layers (0.05mm), PLA can achieve a surface quality that almost rivals SLA prints, making it a viable option for molding applications.
  - PETG
- SLA
CNC Machined Mold
- Wax
  - We had the option of CNC-ing wax to make our molds. This wax is a big stronger than normal wax and has a slightly higher melting point, but it is still very easy to cut.
  - Depending on the part geometry, we could either cut the reverse of the part directly into the wax to make a wax mold, or we could cut the part into the wax and cast a second material like silicon to make a silicon mold. The decision largely comes down to material compatability, personal choice, and time availability as this process takes a bit longer.

Two step
- 3D print → Rubber → Plastic
- 3D print → Silicone → Plastic
Single step
- 3D print → Silicone
- CNC → Silicone
  - I (Tyler H.) found this process to be very straightforward. I am comfortable with CNC-ing and I had flat surfaces on the backside of my target parts, so I just had the backside face upwards with all the details cut into the wax. This was a pretty quick process as well since it only required one cast and therefore one cure time, and the precision of the mold comes down to how long you are willing to spend optimizing the CNC. I will add though, that in switching the bits I did set the Z-height of my ball end mill finishing pass ever so slightly lower than the initial facing passes, so I did end up with some patterning that transferred to my parts.