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End of the World Yo-Yo

Fall 2012

Role: Mechanical Engineer
Team: 5 Students (Mechanical Engineering)

Skills: CAD Modeling, Mold Design

Tools: Solidworks, CNC Mill, MasterCAM, Thermoformer, Injection Molding Machine

My team created a yo-yo theme and design and split into sub teams to tackle mold design of two injection molded parts and one thermoformed part.  I owned the thermoformed part and supported on one of the injection molded parts.  I learned how to design a thermoformed part, created a CAD model of my mold and machined the mold, and thermoformed 100 pieces of the part to create 50 two-sided yo-yos.

My team created a Mayan calendar design and we sketched and created the yo-yo design in Solidworks.  I focused on the thermoformed element with raised triangles.  Using MasterCAM, I created tool paths for the CNC Mill.  I used a small jewelers drillpress to add holes at the corners of my triangles to allow the plastic sheets to be drawn fully into the deep triangular pockets during the thermoforming process.

I conducted multiple test runs on the thermoforming machine, altering the oven temperature, heating time, vacuum time, and cooling time.  Our design set the triangles to protrude slightly from green ring, which was difficult to achieve since it required drawing the plastics sheets into the small and deep triangle pockets.  I found the optimal setting combination to most effectively draw the parts, but the triangles were thin and weak features.  In future iterations, I would redesign the triangles to be sub flush, used a different plastic that would mold more robustly, or expanded the size of the triangles.

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