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Posted by John Doe on March 24, 2008, 7:33 pm
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I had high hopes for this stuff. Ordered UHMW polyethylene tube part
number 8705K141 from McMaster-Carr. Banged it on the end of a bolt
and it left marks on the tube. So the high impact resistance is
relative to HDPE polyethylene, fine. I read that you can't drive a
nail through it. I drove a nail through it several times with no
problem. Then I read it's supposed to be 15 times more abrasion
resistant than carbon steel. So I put it on a smooth concrete
driveway and laid a brick on top of it. Pushed back and forth in the
tube slid on the driveway. Pick up the tube and noticed lots of
abrasion. So what do they mean by "more abrasion resistant than
carbon steel"? Does that mean like if you rub it with your thumb for
15 million years it will last longer than carbon steel would? Are
they using a narrow definition of "abrasion resistant" and
"outlast"?
Thanks for any translation of what they're talking about.
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Posted by woodworker88 on March 24, 2008, 7:52 pm
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> I had high hopes for this stuff. Ordered UHMW polyethylene tube part
> number 8705K141 from McMaster-Carr. Banged it on the end of a bolt
> and it left marks on the tube. So the high impact resistance is
> relative to HDPE polyethylene, fine. I read that you can't drive a
> nail through it. I drove a nail through it several times with no
> problem. Then I read it's supposed to be 15 times more abrasion
> resistant than carbon steel. So I put it on a smooth concrete
> driveway and laid a brick on top of it. Pushed back and forth in the
> tube slid on the driveway. Pick up the tube and noticed lots of
> abrasion. So what do they mean by "more abrasion resistant than
> carbon steel"? Does that mean like if you rub it with your thumb for
> 15 million years it will last longer than carbon steel would? Are
> they using a narrow definition of "abrasion resistant" and
> "outlast"?
>
> Thanks for any translation of what they're talking about.
Wherever you got your information from was totally wrong. It's a low
friction material, meaning that an object will slide much easier on
UHMW than it would on another material. However, low friction and
abrasion resistance are two different things. In general, if you have
something sliding over a surface, coating the surface with UHMW will
reduce abrasion to the PART, but possibly at the expense of the UHMW
wear surface. For example, it is often used in jigs and fixtures,
such as custom fences and cutoff sleds, to create a surface that
allows the part to slide easily without expensive ball or roller
bearings.
The nail thing is ridiculous. I use woodscrews and other pointed
fasteners to fasten to UHMW and Delrin all the time.
Is this coming from a manufacturer's spec sheet or some internet fact
file of dubious value?
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Posted by eric h on March 25, 2008, 6:54 am
Please log in for more thread options >
>
>
> > I had high hopes for this stuff. Ordered UHMW polyethylene tube part
> > number 8705K141 from McMaster-Carr. Banged it on the end of a bolt
> > and it left marks on the tube. So the high impact resistance is
> > relative to HDPE polyethylene, fine. I read that you can't drive a
> > nail through it. I drove a nail through it several times with no
> > problem. Then I read it's supposed to be 15 times more abrasion
> > resistant than carbon steel. So I put it on a smooth concrete
> > driveway and laid a brick on top of it. Pushed back and forth in the
> > tube slid on the driveway. Pick up the tube and noticed lots of
> > abrasion. So what do they mean by "more abrasion resistant than
> > carbon steel"? Does that mean like if you rub it with your thumb for
> > 15 million years it will last longer than carbon steel would? Are
> > they using a narrow definition of "abrasion resistant" and
> > "outlast"?
>
> > Thanks for any translation of what they're talking about.
>
> Wherever you got your information from was totally wrong. It's a low
> friction material, meaning that an object will slide much easier on
> UHMW than it would on another material. However, low friction and
> abrasion resistance are two different things. In general, if you have
> something sliding over a surface, coating the surface with UHMW will
> reduce abrasion to the PART, but possibly at the expense of the UHMW
> wear surface. For example, it is often used in jigs and fixtures,
> such as custom fences and cutoff sleds, to create a surface that
> allows the part to slide easily without expensive ball or roller
> bearings.
>
> The nail thing is ridiculous. I use woodscrews and other pointed
> fasteners to fasten to UHMW andDelrinall the time.
>
> Is this coming from a manufacturer's spec sheet or some internet fact
> file of dubious value?
Re: the nail thing - UHMW has enormous compression resistance, so if
you're trying to drive a nail through the plastic without drilling a
pilot hole first, and the plastic is thick enough ( say, 3/4" thick or
better), odds are you'll bend the nail instead of pushing it through.
Same thing with screws - you have to drill a pilot hole first or
you'll likely snap off the screw in the hole.
That's what they're talking about in those areas. You probably had a
thin piece.
Re: the abrasion resistance - UHMW is more abrasion resistant that
steel, but abrading it on a driveway is like taking sandpaper to it.
Sine the carbon steel you're comparing it to is harder then the
driveway material, it's not a fair test - with the steel, you're
actually abrading the driveway surface. With the relatively softer
UHMW, you're actually abrading the plastic.
Here's a link to a discussion group that has more information on UHMW;
http://groups.google.com/group/uhmwtips
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Posted by John Doe on March 26, 2008, 12:26 pm
Please log in for more thread options eric h <ericchagedorn gmail.com> wrote:
...
> Re: the abrasion resistance - UHMW is more abrasion resistant that
> steel, but abrading it on a driveway is like taking sandpaper to
> it.
Sandpaper is the definition of "abrasive".
> Sine the carbon steel you're comparing it to is harder then the
> driveway material, it's not a fair test -
So it's more abrasion resistant than carbon steel, but only maybe if
you're rubbing it with something soft.
>
> Here's a link to a discussion group that has more information on UHMW;
>
> http://groups.google.com/group/uhmwtips
>
>
> Path:
newssvr11.news.prodigy.net!newsdbm04.news.prodigy.net!newsdst01.news.prodigy.net!prodigy.com!newscon04.news.prodigy.net!prodigy.net!newshub.sdsu.edu!postnews.google.com!s19g2000prg.googlegroups.com!not-for-mail
> From: eric h <ericchagedorn gmail.com>
> Newsgroups: rec.crafts.metalworking,rec.woodworking
> Subject: Re: UHMW polyethylene more abrasion resistant than carbon steel?
> Date: Tue, 25 Mar 2008 03:54:58 -0700 (PDT)
> Organization: http://groups.google.com
> Lines: 61
> Message-ID: <9e57f58e-9eb2-418f-96cd-489df1cfd058 s19g2000prg.googlegroups.com>
> References: <mTWFj.16547$5K1.5176 newssvr12.news.prodigy.net>
<7d67f136-e76d-46bf-ae0a-45e12c0e2cc1 e10g2000prf.googlegroups.com>
> NNTP-Posting-Host: 216.75.189.184
> Mime-Version: 1.0
> Content-Type: text/plain; charset=ISO-8859-1
> Content-Transfer-Encoding: 7bit
> X-Trace: posting.google.com 1206442498 23799 127.0.0.1 (25 Mar 2008 10:54:58
GMT)
> X-Complaints-To: groups-abuse google.com
> NNTP-Posting-Date: Tue, 25 Mar 2008 10:54:58 +0000 (UTC)
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> Injection-Info: s19g2000prg.googlegroups.com; posting-host=216.75.189.184;
posting-account=eL6pmQoAAAAN1mezVXz6q6SyrymBmYKK
> User-Agent: G2/1.0
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Gecko/20080201 Firefox/2.0.0.12,gzip(gfe),gzip(gfe)
> Xref: prodigy.net rec.crafts.metalworking:959891 rec.woodworking:1403186
>
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Posted by J. Clarke on March 27, 2008, 8:41 am
Please log in for more thread options John Doe wrote:
> eric h <ericchagedorn gmail.com> wrote:
>
> ...
>
>> Re: the abrasion resistance - UHMW is more abrasion resistant that
>> steel, but abrading it on a driveway is like taking sandpaper to
>> it.
>
> Sandpaper is the definition of "abrasive".
>
>> Sine the carbon steel you're comparing it to is harder then the
>> driveway material, it's not a fair test -
>
> So it's more abrasion resistant than carbon steel, but only maybe if
> you're rubbing it with something soft.
Or something hard.
--
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
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> number 8705K141 from McMaster-Carr. Banged it on the end of a bolt
> and it left marks on the tube. So the high impact resistance is
> relative to HDPE polyethylene, fine. I read that you can't drive a
> nail through it. I drove a nail through it several times with no
> problem. Then I read it's supposed to be 15 times more abrasion
> resistant than carbon steel. So I put it on a smooth concrete
> driveway and laid a brick on top of it. Pushed back and forth in the
> tube slid on the driveway. Pick up the tube and noticed lots of
> abrasion. So what do they mean by "more abrasion resistant than
> carbon steel"? Does that mean like if you rub it with your thumb for
> 15 million years it will last longer than carbon steel would? Are
> they using a narrow definition of "abrasion resistant" and
> "outlast"?
>
> Thanks for any translation of what they're talking about.