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UHMWPE better than Nylon 66 for wear properties?

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David Jupp:
Correct - chemically they are the same stuff, but the length of the polymer chains is much much longer in UHMWPE, making it difficult to impossible to process in conventional plastics processing equipment.

Blow moulding involves an extrusion step to form the parison, which is then inflated in the mould.  Both steps are melt processing, so not suited to UHMWPE.

bry1975:
Arr interesting and the parison acts like an internal balloon? I briefly worked at an injection moulding and blow moulding firm found the operator work to tedious as every 20 seconds I'd have to remove parts. :(

Kinkajou:
UHMWPE has been used to produce implants for some times now. They used to make them with teflon but found it to be better.
Total hip replacements and knee replacements are a good example of the aplication. They are usually used to be the counterpart of an articulation system in which a metal component has to move around a plastic one to increase wear capabilities.

UHMWPE is very resistant to abrasion but can eventually fail due to wear, that is the reason that some hip and knee replacements have to go through a revision every 10 to 15 years of use.

Very biocompatible .
Hip replacement


Knee replacement


Slow feeding and very sharp tools are needed to machine this plastic.

bry1975:
Thanks Kink,

Sounds a useful polymer I'll have to buy some rod sometime.

PekkaNF:
Interesting. Is there easy to find reference for mating surface roughness and hardness requirements as a "bearing" IE. rotary or universal bal joint as in auto parts? Also failure modes would be nice to know. I don't have any immediate need, but I used some POM and found it easy to work with. Teflon creeped easily, was hard to use with mechanical fasteners, hard to glue and worked with a very narow window of mating surface finish (for an amateur).

Pekka

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