Hollow Wheel Manufacturing & Shipping Update #17
This will be a short blog post, but we wanted to keep everyone up to date. We ran through a myriad of material upgrades, increasing the high temperature strength. Through months and months of testing, we are very confident this is the issue.
Here is the new timeline: (use this link to zoom in - https://cdn.shopify.com/s/files/1/0082/2617/7124/files/Timeline_17.png?v=1629135709)
Explaining the timeline: In order to get more orders out faster, I have elected to pulley pursue Task 9 and, for now, omitted, task 8, 9, and 10 because this is the lowest hanging fruit and I think task 9 will get us to the finish line with great results.
We saw delays of getting this material just due to engineering new chemical compositions and the delta variant in Asia has been impacting production of new materials as well as shipping.
We tested completely new formulations of the TPU as well as started to test vastly different materials, working with many engineers from other companies, to help maintain the grip, high temperature resistance, comfort, and mold-ability of the material.
Here are some new photos of the wheel (they look exactly the same, but they're much different):
When you start to test different materials, the shrinkage of other materials are different so the tests can get us close enough. Materials whether polycarbonate, ABS, TPU, and so on and so forth all have different shrinkage rate. In other words, for injection molding, in particular, you are heating up the material to become a liquid, then you inject it into a relatively cold mold. The material cools and then takes shape once again. During this cooling, a material can shrink more and this can introduce warping.
Of course, when you have material that has warped, you need to be over-molding the Soft outer layer of the wheel and so the mold won't be able to seal around the core and avoid "flash". During the molding process, the material is injected into the mold at very high pressures. So then you get a little bit of this flash or spilling of material. So I have to clean up the wheel, but it will still be able to allow me to test the wheel. Just requires a lot of manual labor for me. If this wheel material configuration turns out to be the best, then we have to touch up the mold to compensate for the shrinkage of the new materials so they can seal very well and avoid flash or spilling of the material.
All the molds have been designed for a TPU variant, so the new materials we tested warped a little bit so I'll have to, for instance, remachine the molded wheel so that bearings or the ABEC or KEGEL holes fit, but that will allow me to get an idea if it is a superior material configuration by running tests with controlled variables. That won't take very long for me, maybe a couple of hours, but it will allow me to test many variables for these brand new materials that I think will add a lot of factor of safety in temperature resistance.