Week 14: Molding & Casting

This week, I made my first mold to cast an object in silicone.

For the group assignment, we used an existing mold and tried different casting materials, such as Ecoflex and liquid plastic.

For the individual assignment, I made a stress toy using silicone.

I was inspired after a short chat with ChatGPT, and then I found an image that I decided to use as my design.

To choose the right material, we first checked the Shore hardness scale from Smooth-On, which is the one available in our lab and is shown below.

We can see each material's hardness on its package or online and decide which one to use.

I chose to use Sorta Clear, which has a Shore hardness of 18A.

I chose this material because it is clear, and I wanted to add glitter to my stress toy. Here is the material sheet:

To make the mold, I used SLA to ensure a good surface finish, and I designed it in Fusion 360.

I designed the mold in Fusion 360 as two parts that join together, with holes to allow material flow and ensure easy removal of the object.

Here is the design:

You can download the .stl from here.

And here is the .f3d file here.

After designing the mold, I printed it using an SLA 3D printer. Here are the steps I followed:

After printing, I removed the supports, cleaned the mold, and cured it.

After post-processing, this is how the final mold looks.

After making the mold, I moved on to the casting part by following these steps:

Calculate the amount of silicone needed by knowing the volume of the mold.
Put an accurate amount of each part, A and B, in different containers. I used 200 ml of part A and 20 ml of part B, knowing that the ratio is 10:1 by volume, which is written on the package.