Milestone #2 - Everything Done (Kind of)

Over the last two weeks, Sustainabiliteam finalized its molds for thermoforming and injection molding. With the exception of a few finishing touches, everything is done. We have a very structured work plan moving forward in order to ensure everything is perfect. We have ordered this blog post by part in order to document progress per part over the last two weeks.

Inner Casing

The inner casing by far was the most challenging aspect of the entire yo-yo. Ensuring that the shutoff surfaces were absolutely precise was a very challenging task that required us to re-machine the mold multiple times. Upon creating a cavity and core that actually closed, we used the injection molding machine to create the plastic part.

However, we ran into issues. Our part did not fully form, and at a certain point, the plastic got stuck in the sprue hole. It required a lot of effort to clean out the plastic and remove the mold from the machine. Below are some pictures outlining that issue.

Moving forward, we determined what the best injection molding parameters were, but we figured we needed to modify and give our molds a better surface finish. We were able to complete that this last week, and on Friday, we used the IM machine again to create our plastic part.

After validating this process, we insert molded the nut and screw into the plastic part. This ensured that we were able to do this step of the manufacturing process correctly, and we feel very confident in mass-producing our inner casing moving forward.

As a summary, the issues we need to fix are:

1. Bearing slides out - Mold may require some additional modification and machining around the bearing. We will wait until we see how the bearing interacts with the other parts of the yoyo

2. Flash - At this point, it probably will be best for us to post-process the flash.

3. Finish not as good on some edges - This might require slight modification, but not enough to cause major changes in the mold.

Outer Casing

The outer casing was one of the simpler molds to machine. Our first set of molds was off from one another which meant that we had to re-machine. Upon re-machining, we were able to make some very good plastic outer casings.

The next step was to determine whether or not the snap-fit would work. We found that the other casing was slightly too large. The next steps could be modifying the inner casing mold to encompass a larger diameter or we could re-machine a smaller outer mold.

Major issues to fix include:

1. The part is uneven - New mold might be required

2. Snap-fit doesn't work - New mold required for sure.

Wind Turbine

The wind turbine mold was machined to be a bit larger to ensure a tighter fit with the bearing. That was the only modification needed, and the wind turbine should be good to go.

Water Plates

The water plates have currently been tested and laser printed on wood. We have made an order for blue acrylic, but from a design perspective, the plates seem pretty accurate. Some tweaks are needed for accuracy to be compatible with the thermoformed earth, but for the most part, the plate looks great on both sides of the yo-yo (Eastern and Western Hemispheres)

Thermoformed Earth

The thermoformed earth was printed for both hemispheres in a variety of different ways. We were able to make dies for both hemispheres and also created a textured version of one of the hemispheres.

Some modifications will be necessary in order to create a more well-outlined continental structure, but we expect that it won't take too long to do. The water plate fits fairly well on top but, there are also modifications needed for that. We 3D printed our dies, and we will continue doing so. We also will need to modify the thermoformed part with a hole in order to fit with the bearing.

In summary, we need to do the following:

1. Reprint the dies with modifications to create better continental structure and fit the water plate

2. Find a way to put a hole in the center of the part - Hole punch

Other

We also need to ensure the entire fit works. That will result in certain modifications to pieces of the yo-yo.

We are very excited to see great progress over the last few weeks, and we are very confident in the success of our yo-yo into the next month.