Summary and Reflection

 The bulk of our material cost is in the ball bearings embedded into the body. The ball bearings cost $2/ea, making up 66% of our yo-yo's $3/ea material cost. Adding in energy and labor costs, and based on our assumptions, our total variable cost per yo-yo is $4.83, which is pretty inexpensive compared to other yo-yos from our class.

Of course the real cost driver in a manufacturing run is amortizing the fixed costs of capital. Injection molding machines, thermoforming machines, and CNC lathes + mills are very expensive pieces of machinery, and we estimate approximately $700,000 could be spend on those machines.

This indicates that were we to enter into production, we'd likely be better off working with a contract manufacturer on their line rather than investing in our own machines, until we get to around 100,000 parts. At that point, we're dropping below $10/yo-yo, and starting to level off, so some consideration could be made about what advantages having our own factory would bring.

A log-log plot of projected cost per yo-yo vs number of yo-yo's manufactured. Fixed costs amortization causes the cost per yo-yo to asymptotically approach the variable cost.

When designing our yo-yo, we did so with the tool capabilities of 2.008 in mind, so we didn't have to compromise much on our designs. Had we been able to accommodate a 3 or more part mold, we could have incorporated some different snap joint designs, but our existing design worked well enough. Embedding more components would improve assembly time, and could be possible with more complex mold tooling. In particular, we could embed a small metal post into the spinner to replace the plastic nub, which would make pressing into the bearing less delicate and smoother. The bearing itself could be insert-molded into the body at the time of injection, which would reduce secondary assembly time. Locating features like pegs and holes could be molded into parts to improve the assembly process. Steel and/or actively cooled molds would improve our cycle time.

2.008 was a tremendously valuable experience for our team diving into the manufacturing mindset, and that mentality will help us be better designers upstream of manufacturing. Simply knowing what different kinds of processes exist and what sorts of parts they're good for is very valuable. Likewise, being able to do a QC analysis on samples to adjust tolerances and/or control limits is critical to having a smooth production run. 

The most value is gained from experience, and if I had to focus on one aspect I think could be improved, it would be the earliest labs introducing how to use MasterCAM. One alternative to consider would be having some tutorial videos as homework before lab, and having lab be the time to generate and verify toolpaths for the paperweights. More experience using the tool to build our own parts could be helpful.