Only Shooting Stars Break the Mold

We've been busy working on our aluminum mold designs this week. After learning how to use Moldflow, we've been able to estimate the resulting shrinkage for each parts and adjust our mold designs accordingly. We are preparing to deliver our Go-to-Manufacturing Reprort next week as if we were submitting it to a supplier to receive cost estimates for mass production. The goal is to operate at a scale of producing 1,000,000 yo-yos a year.

Liquid Bottom 

I'm concerned about the injector pin locations being on the conical surface, but there's no other good place for them

Liquid Top

Here is are the two mold halves for the the liquid top. We currently don't have any major concerns with the design, altough a few dimensions did have to be changed slightly to accomodate avalable tool sizes. 

Lime

The lime design was adusted to remove material from the center and improve wall thickness homogeneity. We will need to use a special flat endmill to make the thin rib features that we don't have in the lab. Fortunately, we found a 0.020" endmill on McMaster-Carr (8915A22) that will do the job.

The quality of the part is very high overall, with just a few spots that can be explained by sink marks. Moldflow simulation indicates that the shrinkage for the lime is 0.986%. An additional gate was considered but did not affect the shrinkage enough to be included in the mold design. Overall, this is a small piece and the quality prediction is high, as well as a 100% confidence of fill, so we are happy with this lime.

Glass

This is the die for thermoforming the glass. There are no major concerns with the design, and it should work very well for thermoforming because of its moderate slope. The tool path might need some changes to reduce time while achieving the final shape, but otherwise, it is near completion.

Factory Planning

For the Go-to-Manufacturing report, we will need a detailed plan of our ideal factory layout as well as cycle time estimates and operational parameters needed to determine factory costs. We have begun to compile injection and cooling time data from Moldflow siulations as well as assembly time estimates from collecting empirical data on the time it takes to assemble LMP yo-yos. The LMP yo-yos should be a good proxy for our yoyo as both yo-yos require one main press fit as well as a thermoformed part per half. Our yo-yo includes an extra small press fit, the lime, which we can take into account with a safety factor or by simply timing an additional pressfit. Once we are satisfied with our time estimates, we can begin figuring out how many of each machine we will need and what our factory floor will begin to look like. We will, of course, take into account the variability of the yo-yos and determine what percentage of them will need to be rejected for quality assurance. This will directly impact the effective rate at which we can produce yo-yos. We can potentially use the empirical variability data collected for the LMP yo-yos as a way to estime the variability of our yo-yos.