Design Challenge — Rhianna La Chance

Tolerance stack -

Dimensions of box to slip fit with suction, diameter of plug to interface with mug

Assumptions

Box top and bottom have a max distance of 0.006mm to achieve Apple’s signature suction
opposite sides will deviate equally
Min. ID of mug > 78.994mm

Worst case will be when top box inner dimensions are at their max, and when bottom box dimensions are at their min. Given the tolerances at worst case, the adjusted distance from the both sides to the plug would be adjusted given the sum of top and bottom tolerances — 7.18mm + 0.006mm & 7.19mm + 0.006mm. This would scale down the diameter distance from 78.994mm to 78.988mm

pulp molding Process

analysis examples

One thing I analyzed was the “buffer zone” needed under the mug to not break from a 6’ drop test. After converting KE into impulse energy and analyzing molded pulp’s stress-strain relationship, I got an unreasonable box height of 0.5m. Although I don’t think my math is incorrect, the assumed values for interference, deflection, and deformation could be problematic.