Way off topic - plastics help please...
 

I note there's a lot of general knowledge out there in this group and
I have hopes that someone is familiar with plastics to make some
suggestions. I've cross posted to one other group.

I'm not familiar with what all is available today in the plastic/
polymer field. What two plastics, choosing, say, PVC, Polyethylene,
UHMW, ABS, and so on, are the slickest, or will wear well against ONE
ANOTHER?

I'm using a 2" UHMW piston in a PVC cylinder and the wear seems to be
OK, but I really feel there's something better and probably "slicker"
against one another out there than what I'm using now...

Teflon is pretty prohibitive for cost, I do know that...

Any ideas or experience out there?

Thanks in advance...

Bill

Way off topic - plastics help please...
 

npwbill writes:

I'm using a 2" UHMW piston in a PVC cylinder and the wear seems to be
OK, but I really feel there's something better and probably "slicker"
against one another out there than what I'm using now

UHMW-PE is self-lubricating but the PVC may have filler that is abrasive.

Teflon is pretty prohibitive for cost, ...

You can get bondable PTFE sheets to line things with for ultimate lubricity
at low cost.

Way off topic - plastics help please...
 

On Thu, 14 Feb 2008 00:59:26 -0600, Richard J Kinch wrote:

npwbill writes:

I'm using a 2" UHMW piston in a PVC cylinder and the wear seems to be
OK, but I really feel there's something better and probably "slicker"
against one another out there than what I'm using now

UHMW-PE is self-lubricating but the PVC may have filler that is
abrasive.

Teflon is pretty prohibitive for cost, ...

You can get bondable PTFE sheets to line things with for ultimate
lubricity at low cost.

Small Parts, Inc. has PTFE o-rings. Dunno what your price point is
between 'affordable' and 'prohibative', but a couple of them on a piston
will be cheaper than a whole piston.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

Way off topic - plastics help please...
 

On Wed, 13 Feb 2008 22:17:35 -0800 (PST), npwbill
wrote:

I note there's a lot of general knowledge out there in this group and
I have hopes that someone is familiar with plastics to make some
suggestions. I've cross posted to one other group.

I'm not familiar with what all is available today in the plastic/
polymer field. What two plastics, choosing, say, PVC, Polyethylene,
UHMW, ABS, and so on, are the slickest, or will wear well against ONE
ANOTHER?

I'm using a 2" UHMW piston in a PVC cylinder and the wear seems to be
OK, but I really feel there's something better and probably "slicker"
against one another out there than what I'm using now...

Teflon is pretty prohibitive for cost, I do know that...

Any ideas or experience out there?

Thanks in advance...

Bill

I think you'll have to experiment. Teflon may not be the answer. As
an aside, I once visited K2 (ski maker) on Vashon Island near Seattle
on business. I asked about Teflon for the running surface, and was
told they had tried it, thought it would be great, but it didn't run
nearly as well as UHMW.

That was a beatiful facility, by the way. The VP of R&D we were
visiting with was dressed in jeans, polo shirt, and sneakers, and had
the help loading up the van for a run up the mountain for some field
tests. What a gig.

Pete Keillor

Way off topic - plastics help please...
 

On Wed, 13 Feb 2008 22:17:35 -0800 (PST), npwbill
wrote:

I note there's a lot of general knowledge out there in this group and
I have hopes that someone is familiar with plastics to make some
suggestions. I've cross posted to one other group.

I'm not familiar with what all is available today in the plastic/
polymer field. What two plastics, choosing, say, PVC, Polyethylene,
UHMW, ABS, and so on, are the slickest, or will wear well against ONE
ANOTHER?


I can't tell you what will be slickest or longest wearing, but a
couple common combinations that work well are Delrin(acetal) on
Nylatron(moly filled nylon) and Delrin/UHMW. Both Nylatron and UHMW
are used for the slider beds and wear strips in conveying systems with
Delrin chains. Rex Tabletop, Sideflex, and Multiflex are examples of
this type of chain. It's been a long time since I've used any of
these, but I'm pretty sure Rex has data in their literature.

Here perhaps:
http://www.delzer.com/v5fmsnet/LinkP...x/8rxEM-en.pdf

--
Ned Simmons