Team 3502 has tested some different materials for friction on HDPE, they are ranked in order of highest friction to lowest friction below. Unfortunately, we have no actual numbers for CoF, everything is relative.
High friction
Silicone bar/sheet (about 20A-30A durometer)
AndyMark 4" Stealth Wheel (77A TPU)
BaneBots Blue wheels (50A TPR)
BaneBots Green wheels (30A TPR)
KOP “Grip Material, 1 in. wide, 18 in. length” (The Part# in the KOP list just goes to the adhesive on the back)
(when flat against HDPE, very high friction, but when wrapped around a wheel, moderate-low friction)
Moderate friction
AndyMark Clear HiGrip wheel
Low Friction
“Old” AndyMark Omni wheels](http://www.andymark.com/product-p/am-0903.htm) (rollers, 80A SBR)
This test came about because of our concern about the AndyMark Omni wheels. Does anyone know what material the rollers of the VEX omni wheels are? Has anyone who has the AndyMark DuraOmni wheels(77A TPU) tested them on HDPE?
Hopefully, this will help teams wondering about high friction materials on HDPE. I wish we had had more materials to test, but this is it for now.
If anyone else has tested similar things, please post your results. I will be happy to update when we test more materials. Thanks!
EDIT: The reason for the casting polyurethane in the title is that it is an option that we are considering. Does anyone have any experience with it?