HMWPE v HDPE

[limpet]

Is HMWPE as good as HDPE for robot use?
I`m looking at drilling and threading it, I`ve done it with HDPE and its fine but want to check before I buy it.
Thanks

[Ellis]

Just means High Molecular Weight Polyethylene, or often it's called UHMWPE (Ultra...) - I believe it's the same material, just two different naming conventions. It seems the US called it UHMWPE and we call it HDPE. Should behave very similarly if not exactly the same.

[joey_picus]

I think it is a little different, it's always seemed harder and slightly less deformable and more brittle than HDPE to me (although 'brittle' here is very much a relative term). I don't think it should work too differently for the purposes of robots though.

[overkill]

UHMW and HDPE have different properties but as Ellis mentioned, the naming conventions are a bit hazy. UHMW has longer molecule chains, is more abrasion resistant and more flexible than HDPE. To make it more confusing, manufacturers use additives to change those properties even further.

To me, HDPE is always a bit stiffer and harder, while UMHW usually has a slick & slippery feel compared to HDPE. I really wouldn't tap UMHW unless you are using VERY coarse threads. I use sheet metal or plastite screws, but only in non-structural areas.

[maddox10]

The HDPE and UHMWPE sometimes are named for their molecule chain lengths. That is when you get HDPE 500 and HDPE1000.

The more slippery one is the 1000, what is less weldable, but bending is a tad easier.

[Eventorizon]

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.

[limpet]

Thanks everyone, I`ll get it and see how it goes.
Its actually listed as HDPE 500 so it could be its just a different grade (last lot I got was 300), but elsewhere it lists them as HDPE 300, HWMPE 500 and UHMW 1000.
I`ll post back on here when I know the results (after Insomnia probably!)