For the past ten weeks, my design class has been building a thermoforming machine from scratch. Thermoforming is a very useful process where a sheet of plastic is heated and draped over a mold, then the air is vacuumed out of the plastic. Once the plastic cools, an outer mold is released and can be used for many machining processes. I was selected to be one of six project managers, each in charge of nine other students. My group was the mechanism group, and I was responsible for coordinating with the plastic holder, heating element, vacuum plate, vacuum system, and frame groups. The mechanism’s role is to move the plastic holder between the heating element and the vacuum plate.

Our design consisted of two hinged lever arms to provide mechanical advantage, and shafts with linear bearings to provide vertical motion. We overcame many issues during the final week of testing, including a singularity in our lever arms, excessive racking, and magnets strong enough to hold the plastic holder at the top of its range. We were able to move the lower pivot point for our lever arms, realigned our bearings and installed guiding springs, and created a backup hook mechanism to replace the magnets. I am very proud of my team for working hard to make everything work in the final week.

The mechanism was very dependent on the other components, and in fact very little could be assembled or tested until the rest of the system was built, as our pieces were completely based on other parts. The plastic holder was delayed, which meant that our group only had one or two days for assembly and testing. Even though our design for connection to the plastic holder and the frame was modular, allowing all of our pieces to be disassembled and replaced, we still needed the other systems to be completed in order to prepare alignment. I learned how to coordinate with other groups, make a manufacturing schedule, and debug with limited time. We are incredibly proud of our design and how much it improved over the course of the semester.

You can view our final design report and Creo drawings here.

Even though this project was incredibly frustrating at times, the successes of debugging and thrills of machining made it all worthwhile. I would do it again in a heartbeat.

Keep thinking!

~Annie