Precious Plastic UC San Diego

DESIGNING AND PROTOTYPING OPEN-SOURCE IMPROVEMENTS TO SMALL SCALE PLASTIC UPCYCLING MACHINERY

WINTER 2021 MAE 156B SPONSORED PROJECT
UNIVERSITY OF CALIFORNIA, SAN DIEGO
SPONSORED BY ANDREW KRAUSE, IMPACT MILL COLLECTIVE


About Precious Plastic UC San Diego

For our senior design project, our team is sponsored by the UCSD Design Lab and previous Precious Plastic Senior Design team to create user-friendly machinery for a plastic workspace on campus.


Our project’s machines are adapted from the global Precious Plastic community, whose aim is to reduce plastic waste around the world. They do this in two main ways. The first way is by encouraging people to build machinery that can shred, melt and re-form your recyclable plastics into new products, whether it be through extrusion, injection molding, or sheet-pressing. Designed by the Precious Plastic founders, these machines all have instructions on how to build them and use them on the Precious Plastic website. The second way the Precious Plastic community strives for a reduction in plastic waste is by selling plastic products on their community marketplace, all of which have been built using the Precious Plastic machinery.


So, What Is Our Team Trying To Do?

The Design Lab, the rest of our sponsors and their partners are trying to set up a plastic workspace on campus so that UCSD can encourage students and nearby San Diego residents to recycle their own plastic and come make their own products on-site, thus adopting sustainable waste and recycling practices. The long term goal is to set up partnering workspaces in Phoenix and Sonoma and establish a collaborative online platforms for the communities at these workspaces to share their ideas and designs with each other. However, the Precious Plastic machine prototypes that the team has right now are not user friendly enough for everyone to use. This is where our team comes in!


Our goal is to help redesign the current prototypes to make them more user-friendly. We are specifically focusing on the injection machine. The current prototype can be hard to understand and is not intuitive enough. The previous senior design team had one of their team members hang off the injection lever in an attempt to apply enough weight to push the lever down!

Our Team Testing out the Machine!

Project Objectives

For our team's specific goal during the quarter, we seek to test and improve individual components on our already-built injection machine to further improve it's efficiency and user experience. Here are some primary components that we worked on per request of our sponsor:

  • A method to reduce plastic melt time

  • A sensor package to record different parameters around the injection machine during the injection process and better understand the machine's performance

  • Prevent high-force injections due to plastic buildup on barrel

  • Additional improvements to the machine in terms of User Experience

We are also working to create baseline measurements of the injector's performance. Our designs and research will create a foundation for future students to build upon with further improvements on the machines.

Final Designs

Injection machine labeled with our various component improvements!

Our current design consists of major component improvements that improves the current performance of our current injection machine and it's efficiency:


  • A barrel core, inserted from the bottom of the barrel to assist the currently used heating bands to decrease the required plastic melt time

  • A S-beam force sensor, enabling us to continuously monitor the injection force throughout the process [we are still deciding which exact force sensor to use]

  • A temperature probe, enabling us to monitor the changes in plastic temperature during the the barrel heat-up process

  • An inclinometer, allowing us to observe and record the angle in which the lever is travelling throughout the injection process

  • A mold cage adapter, attached into our barrel nozzle to prevent plastic sprue

  • A handheld hopper, to assist the user in increasing the plastic loading efficiency without encountering problems from the previous design

  • A drilled cleaning brush, to ensure barrel cleanliness after every injection process


As seen above, we have over 8 finished components that are added into the machine for improvement. Furthermore, we have made several more component improvements and design that we are unable to finish due to time constraints - we will go more in depth on these on our Final Design page


Summary of Improvements

With the improvements to the different components of the injection machine, we were able to reduce the baseline to our improved injection cycle time of:

Final Presentation

Final Presentation

Virtual Poster Presentation

finalpres2.mp4