Video, Cost Analysis, and Recommendations

We FINISHED!!! Here is a video of all that we've done this semester! Check it out to see our process from beginning to end.

Summary of our cost analysis for prototyping vs. manufacturing:

Yoyo cost contributors are broken down into fixed and variable costs. Fixed costs don’t scale directly with production and include yoyo design and mold machining time. As we have a relatively short run of parts, molds aren’t consumable. Other costs scale with the yoyo, such as raw materials, injection molding overhead, thermoform overhead, and labor. Factoring in everything for our final run of 50 yoyos, each cost about $86 counting in student hours, design, machine and manufacturing time, and materials. Because the per-yoyo overhead is very small compared to fixed costs, manufacturing at larger scales would radically decrease the yoyo’s total cost.

How our YY design was adapted to meet the constraints of the 2.008 manufacturing

equipment, and how you would change it for mass production:

Lasercut Wheel: For mass production, the laser-cut wheel would be injection molded (or extruded and then cut), as the lasercutting process has a higher cost and a lower rate of production.

Wheel of Fortune Overmolded Board: For our assembly, we decided to overmold as a challenge, since we heard it was difficult (and it was). For mass production, however, we would recommend using stickers instead since overmolding is time-consuming and difficult to optimize.

Our team’s recommendations for improvement of the 2.008 class:

• We greatly enjoyed the team project portion of the class! It was a well-designed lab that brought together many different features of the manufacturing process together - CAD (and design), machining, injection molding, thermoforming, and key features on design for manufacturing, design for assembly, and the optimization processes. It was also relatively easy to divide up all the parts to individual team mates, and debugging processes are made easier with multiple people. Dave and David also do a wonderful job of helping us solve problems with our molds and production.
• The spacing of yoyo deliverables clumped around the beginning and end of the semester, with few assignments in the middle. While the earlier deliverables occur week after week, there is a period in the middle of the term when we are working on optimizing our molds and runs but the deliverables were minimal. It would be optimal to evenly distribute this work somehow – perhaps the production of all molds should be finished by a certain date, or the production of 1 yo-yo should be completed before Milestone 11.
• While we agree that there should be some individual portion to 2.008, many of the homework problems were difficult to do on our own and there is much value in learning from our peers when psetting. Possible having some other way of measuring our individual understanding of the material, while preserving the opportunity to learn from others through psets would work better.
• Unfortunately, we had three lab groups in our section, and since most machining time could only be booked during our lab sections, this meant that, especially at the beginning when machining the first molds, there was a line for machining during our lab time, a problem that other lab group did not experience. Perhaps having a designated machine shop time for groups with 3 lab sections may be useful.
• The CAD/CAM labs were great for learning Mastercam! Though, we would have liked to see less depth covered in lab time, as it is a lot of information presented at once. Having the information available somewhere where we can access it at any time (like youtube tutorials or written tutorials in the course locker) would be really helpful when working on our molds outside of lab time. Comprehensive written tutorials for Mastercam would eliminate the need to do tutorials during lab time, thus lab time could serve as an office hours for Mastercam.
• During class lecture it would be wonderful to have more of the information that is verbally articulated also written on the slides (or possible on the handouts have extra notes). Some slides just have equations or pictures with little explanation written, so if I did not understand it well enough when it was said during lecture to write good notes, it would be hard to get the information later. Summary slides of key points through out the lecture would also help to solidify my understanding.

From all of us here on the Wheel of Fortune 2.008 team, we want to say thank you for following our progress!

Best,
Melody, Kath, Melanie, Skyler, and Alexxis