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12. Molding and casting

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Assignment Overview

Group assignment:

  • review the safety data sheets for each of your molding and casting materials,
  • then make and compare test casts with each of them compare printing vs machining molds

The group assignment page can be found on the Energylab 2024 website here

it is also embedded directly in the webpage below.

Individual assignment:

  • design a mold around the process you’ll be using, produce it with a smooth surface finish,
  • use it to cast parts. extra credit: use more then two mold parts

This week, I explored molding and casting techniques by creating a five-pointed star. The process involved designing the star in FreeCAD, fabricating a mold using 3D printing, and casting the final object in silicone. The goal was to understand and practice the steps of modeling, fabrication, and material handling to achieve a high-quality molded object.

Process Workflow

  1. Design in FreeCAD

  2. I started by designing a five-pointed star with a clean and symmetrical geometry:

  3. The base shape was created using the polygon tool and set to 5 sides.

  4. The star was then extruded to give it a 3D form, with dimensions suited for easy handling and casting.

  5. A border was added to the star to enhance the final design.

  6. The design included draft angles to facilitate demolding and prevent the silicone from sticking to the mold.

  1. Mold Design

  2. Using the 3D star model, I designed a two-part mold in FreeCAD:

  3. The mold’s base included a cavity shaped like the star.

  • Instead of using alignment pins, I opted for a male and female frame design for the mold
  • The male frame is integrated into one half of the mold, while the female frame is on the other half.
  • This approach ensures precise alignment of the two mold halves without the need for additional components.
  • The design simplifies the assembly process and prevents any shifting during casting.
  • Additionally, the frame adds structural rigidity to the mold, reducing the risk of deformation.
  • Air vents and a pouring channel were incorporated to allow smooth filling of the silicone.

  1. Fabrication of the Mold
  2. The mold was fabricated using FDM 3D printing:
  3. Material: ABS was chosen for its resistance
  4. Printer settings: A layer height of 0.2 mm and an infill density of 20% were used for a balance between detail and strength.
  5. Post-processing included light sanding to smooth the mold’s interior surfaces for a better silicone finish.

  1. Silicone Casting
  2. For the casting process:
    • Material: I used two-part silicone rubber for its flexibility and durability.
    • The silicone mixture was prepared by mixing Part A and Part B in a 1:1 ratio (as per the manufacturer’s guidelines).
    • After mixing thoroughly, the silicone was poured into the mold via the pouring channel, ensuring minimal air bubbles.
    • The mold was tapped gently to release trapped air and left to cure for the recommended time.

File

What went wrong/What went well

For this assignment, everything went well overall. The whole i have make just one small hole. And i have used drill to do more for air buble to go out.

Last update: December 7, 2024