Thermoforming Rig: A MechE Project

October 2018 to February 2018

Supermileage Vehicle at UCLA


Coming to UCLA as a first year, I was eager to get my hands dirty on a project, and luckily in the SuperMileage Vehicle racing team (a branch of Bruin Racing) there was one for me. Thermoforming (also known as vacuum forming) is the process of heating a sheet of plastic until it becomes malleable, then pulling it over a mold and vacuum box so the plastic cools in the shape of the mold. Normally, these types of rigs are around 1' by 2', but we needed a rig that was 4' x 4' to thermoform the windshields of our vehicles. In previous years, there was a completely enclosed box for heating the plastic. After the plastic was heated enough, it had to be lifted out of the box onto the vacuum box and mold. This process created a lot of room for error because the plastic cooled very quickly and anything that touched the malleable plastic could result in a deformity. We needed a solution that allowed the plastic to be heated and stretched over the mold immediately.

I worked together with another first year, Juan Banchs, and we used Solidworks to design a thermoforming rig that was around 4 feet by 4 feet by 4 feet. Essentially, heaters are hung from the top and point downwards onto a sheet of plastic that sits parallel to the floor, held up by pegs. After heating, users can move the pegs out and down to pull the plastic towards the vacuum box that sits on the ground where the plastic forms and cools. In theory, it may sound not terribly complex, but during construction, we ran into a few issues.

To summarize our challenges, the first came when we were designing the rig. Without having time nor resources to create a physical prototype, it was difficult for us to imagine how the moving parts would fit together, and if the moving parts would fit together. To overcome this, we often discussed our ideas out loud to each other and to a third party to make sure it made sense to everyone. In practicality, our main issue was with the dissipation of heat. In the end, we used aluminum insulating material (it was kind of like bubble wrap) that we cut to a certain shape, allowing us to drape it over the rig, like wrapping paper! Another large issue we faced was with the mold we wanted to form over. Originally, we used the front section of our car's male plug (made from high density foam), but because the mold was so large, the plastic was unable to seal against the vacuum box on all four sides and the resulting products were scratched and full of bumps. This issue was sensitive because we had a limited number of plastic sheets, and each one we messed up was around $50 down the drain. After a lot of brainstorming and deliberation, we approached a plausible solution: since we were forming the windshield of the car, we found the carbon fiber piece that we cut out of the car (to replace with the windshield) and formed over that. Since it was pretty flexible, we got creative and supported the cutout with various blocks of wood and metal to prevent it from caving from the vacuum... and it worked! In the end we saved the club a few thousand dollars and successfully formed windshields for both vehicles.

Main Takeaways

From this project, the main thing I learned was to never give up and always keep looking for a solution because there's always one out there! A large influencer on this is also your attitude. Even when things got difficult and it was so tempting to just give up, Juan and I stayed optimistic and open minded and always ended up creating or stumbling across a feasible solution. I also learned that I really love working with others, especially on larger projects! It's really beneficial for me to have someone to talk to about my ideas, and while at some points I like to get work done on my own, to know that I have someone who supports my work just as much as I support theirs is very reassuring.

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