WEEK 14 - Molding and Casting

The Molding and Casting group assignment focused on understanding the materials, processes, and safety considerations involved in producing molds and cast parts. The objective was to investigate how different molding and casting materials behave during mixing, curing, demolding, and final use, while also evaluating the influence of fabrication methods on the quality of the final result.

As a team, we reviewed the Safety Data Sheets (SDS) of the materials used throughout the assignment to identify hazards, handling requirements, personal protective equipment (PPE), and recommended working conditions. This step was essential to ensure that all experiments were conducted safely and according to the manufacturers’ recommendations.

The group also produced and evaluated test molds and casting samples using different materials. Through these tests, we analyzed curing time, flexibility, dimensional stability, surface finish quality, ease of demolding, and suitability for digital fabrication applications.

1. Designed the cat relief model for CNC machining.
2. Prepared the CAM toolpaths and machined the mold.
3. Corrected the milled surface by sanding the tool marks.
4. Sealed the milled mold to reduce porosity and improve release.
5. Prepared and mixed the silicone material.
6. Poured the silicone into the CNC-machined mold.
7. Allowed the silicone to cure and demolded the flexible mold.
8. Prepared the EPOX-21 epoxy resin.
9. Poured the resin into the silicone mold.
10. Waited 72 hours before demolding.
11. Demolded the final resin piece successfully.
12. Documented the final hero shot of the mold and cast object.

The process started with the digital preparation of the cat face relief. The model was placed inside a rectangular mold frame so that it could be machined as a positive master. The design had to include enough border and depth to allow the silicone to be poured later without leaking.

The cat mold was fabricated using CNC milling. The tool removed material layer by layer until the face, ears, eyes, nose, whiskers and surrounding cavity were created. After machining, visible tool marks remained on the surface, especially in curved areas.

After milling, the mold was corrected by sanding. This step was necessary to reduce the toolpath marks and obtain a smoother surface finish. The goal was to prevent the production process from being visible in the final cast.

The milled mold was sealed before pouring silicone. Sealing reduced the porosity of the wood-based material, improved the surface finish, and helped the silicone release more easily after curing.

The silicone mixture was poured slowly into the CNC-machined mold. Pouring from one side allowed the material to flow naturally across the surface and helped reduce trapped air in the detailed areas of the cat face.

After curing, the silicone mold was carefully removed from the CNC master. The flexible mold captured the cat face details and was ready to be used for resin casting.

For the final casting stage I used EPOX-21 epoxy resin. The material included component A and component B. The resin was mixed slowly to avoid bubbles and to obtain a uniform mixture before pouring it into the silicone mold.

Once the resin was mixed, it was poured into the silicone mold. The resin was added slowly so that it could fill the detailed areas of the mold and reduce the formation of bubbles.

This hero shot presents the complete result of the molding and casting workflow developed during this assignment. Starting from a digitally designed cat relief, a CNC-machined mold was fabricated and subsequently improved through sanding and sealing to eliminate visible toolpath marks. A silicone mold was then produced from the CNC master and used to cast the final piece using EPOX-21 epoxy resin.

The resin was mixed according to the manufacturer's specifications and poured carefully into the silicone mold. To ensure complete polymerization and dimensional stability, the cast remained undisturbed for 72 hours before demolding. The final result successfully reproduced the geometry and details of the original design while achieving a smooth surface finish and good structural integrity.

This outcome validates the complete workflow of digital design, subtractive manufacturing, mold preparation, silicone molding, resin casting, and final demolding. The project demonstrates how CNC machining and casting techniques can be combined to create accurate and repeatable parts with high-quality surface finishes.

• Linked to the group assignment page and reflected on my individual page what I learned
• Reviewed the safety data sheets for each molding and casting material
• Documented how I designed and created my 3D mold, including machine settings
• Ensured the mold has a smooth surface finish
• Shown how I safely made the mold and cast the parts
• Described problems and how I fixed them
• Included design files and hero shot of the mold and final object