Thermo-Form and casting Project

Design For Manufacturing

November 2024

The Goal:

Creating an aesthetically pleasing succulent holder.

For this project, students were to create a plant holder with at least one vacuum-formed part and one urethane-cast part. My project partners and I created a three-part plant holder, inspired by nature.

And thus, we created a snail-cculent!

Main Design Requirements:

- It should be able to hold a potted plant

- At least one part needs to be urethane cast, and at least one part needs to be vacuum formed

Skills Developed:

- Vacuum Forming experience

- Urethane casting in silicone molds

- CAD skills with draft angles and manufacturing method in mind

Some challenges encountered in this project include the following:

- Dimension considerations

The urethane casting parts were limited by the amount of urethane we could use. The vacuum-formed part's dimensions were limited by the dimensions of the former. These concerns were tackled by scaling the parts to fit within our dimension constraints while allowing them to complete their desired function and aesthetic purpose.

- Machining considerations

Since the parts were urethane cast and vacuum formed, vent holes were added to our models and molds to help with the formation of these parts. The urethane 3D parts also had to have peg holes to help align the silicone mold once we split it up.

- Urethane casting mishaps

We had problems setting the mold and pouring in the urethane.

First, we did not mix the silicone fully enough, so there were still uneven parts to our two solution mixes. This caused parts of the silicone to dry unevenly and affect the mold. Furthermore, there were some air bubbles in the silicone due to the mixing technique, which could have also been avoided.

Finally, in our first attempt at pouring the urethane, we forgot to band the silicone mold together, which caused the urethane to pour out. This was solved by using rubber bands to keep the mold together. We also later kept the mold in its plastic box (shown in the third image below), which kept the mold intact.

Results:

The final assembly put together was really cute and decently achieved our aesthetic goals. From a manufacturing standpoint, we were able to learn the basics and conduct our own castings. In terms of actual finishes, the urethane casts are a bit trickier to make sure they are well-made. Since we conducted a two-part pour for our urethane castings, how we put the two silicone parts together dictated how visible the seam line was on the final product. We also did not correctly mix the silicone well enough (which caused holes to appear in our final product), but also the coloring of the urethane was not mixed fully well. The rough finishes could be fixed with some sanding, but the colors would have to change in the next iterations of the process.

Overall, this project was insightful for creating interesting, organic shapes and allowed first-hand experience in these processes.

Below is the cost analysis conducted. We did not account for the working time for the product, and if we had done so, the price of each snail-cculent would be higher. This would also be the case since the silicone molds deteriorate over time, and so, we would need to re-buy materials every time they become unusable.

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