As an example - the road gritters in the UK use 25mm HDPE (500) to make their distributor discs onto which they bolt the fins that fling out the grit into everyone's windshields. This is considered a consumable part and is just a disc of HDPE in it with some holes for bolts.

They use 10-15mm UHMWPE (1000) to back the signs and custom mudguards/deflectors that are needed on certain models as it can withstand the abrasion of the grit for longer, is stiffer and is easier to clean.

How that all relates to robots I don't know but there is a pair of real world applications to mull over.