Optimize, optimize, optimize! (BD#3)

Apr 24, 2017
2 min read

As a team, we have certainly come far! The following is an update on our progress as we optimize the molds we have and reflect on adjustments and readjustments (and re-readjustments) to our designs.

The following are process sheets for the inner silhouettes and heads for the inside of the yoyo. These were featured in our last blog post.

These are the testing/optimization sheets for all three colors of these silhouettes. All of these pieces are injection molded and we decided on the parameters with a snug snap fit in mind. In order to have silhouettes of different colors and have the silhouettes be distinct and easily recognizable, each was planned in order to snap fit together. Additionally, each silhouette has carefully crafted and slight details from engravings on the mold to give it an extra touch. It was important that while optimizing that the holes and pins for fitting came out undeformed and unshifted and that all the details of these small but significant pieces were clear. During the optimization process, the settings were adjusted such that short shot and flash were both avoided and that these key aspects of the parts were maintained. The red mold was the last of these to be tested as noted the mold needs to be re-reamed and the gates opened a bit more before another optimization trial and then finally production for these parts.

A few pictures of the testing results are below.

Additionally we made immense progress on all of our parts. The window of the yoyo was thermoformed (process plan shown below).

There was a slight adjustment then readjustment to the diameter as it was fitted with the snap ring and the base. The final adjustment will be decided this week so we can finish optimization and move on to production!

The process sheet for the base is shown below.

The parameters in the process optimization sheet are currently outputting small signs of flashing around certain edges of the yo-yo. This can be solved by adjusting packing time, pressure, and plastic flow velocity. A major issue that came up with the injection molding of the base was shrinkage around the external angled wall of the base that comes in contact with the string. We found out that keeping the part in longer actually made shrinkage worse than keeping it in for a shorter amount of time. The inner diameter of the snap ring groove fits the clear thermoformed window perfectly, however some rework needs to be addressed for either the snap ring or the existing base, because the OD of the ring is much too large for the snap ring groove. The spacer core and cavity are currently being machined and the optimized parameters for that will be posted shortly.

The snap ring process sheet is shown below.

The snap ring really encapsulates the theme with it's engraved words and clean design. The only readjustment for this piece is due to the previously mentioned adjustments. With all this in mind, we are excited to confirm our assembly strategy and move on to production.

Here are a few of the pictures from this process: