Brr...roadblocks

This week, our team began machining our first molds, injection molding them, machining the shoulder bolts for the body, as well as 3D printing the stand and snow-yo dome to test thermoforming. We completed machining the body core, body cavity, snap ring core, snap ring cavity, and nose cavity. We also tested injection molding the body and snap ring. A main goal of our team is to stay ahead of the class imposed deadlines, so we can account for any problems that may come up; already, we've run into a few road blocks that we'll discuss in this blog post.

When beginning to injection mold our body, we ran into instances of shortshot. We realized that this was because the volumetric calculation of our part did not include the volume of the runner. We were quickly able to fix this, but we then began to encounter burning of our body part, as well as significant shrinkage making it difficult for the snap ring to fit. We worked towards a solution to this by increasing packing time and cooling time, as well as drilling a large hole partway through the back of the mold near the burning areas and drilling and collapsing a small hole on the other side to let air out.

Body rings with short shot, resolved with increasing packing time and shot size.

Burn marks in the yoyo body, which were resolved through drilling holes and increasing cooling time.

Now, the burn marks are gone. One problem we are still working to solve is the fit of the snap ring, as it is a bit loose. We will have to adjust the parameters on the snap ring so it fits more tightly.

Two bodies with a spacer assembled together with one dome.

When thermoforming the stand, we found that it was difficult for it to form correctly. To try and solve this, we redesigned the stand to be lower, 3D printed it again, and we are currently testing it to see if it thermoforms better.

Our goals this week include completing more molds, thermoform testing the stand, and fixing the snap ring fit.