What is this plastic?

Doing some new parts for a new customer. A few of his parts, he doesn't have drawings for, as they are purchased from the manufacturer of the
equipment he buys, modifies, and resells.
I have two bushings to make out of plastic, he doesn't know exactly what they are made of. I thought MDS until I compared a sample to the bushing. MDS from McMaster at least, is a sort of gray color and quite hard compared to the sample. Sample part is a very dark charcoal black, and under a microscope it looks like microscopic pits tear out of the material in machining. Also seems to have very minute reflective flakes impregnated throughout. It feels like Teflon, and a trial part I made in Teflon has the right "feel" on the mating shaft. Both materials seem to be about the same hardness. I know about Delrin AF, and it's certainly not that.
I've never seen a black Teflon before. Almost like graphite filled... Ring any bells?
Thanks,
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Oct 2005 18:28:57 -0700, Jon Anderson

It exists. Google it.
I tried to use bronze filled teflon for a seal once. What a disaster. It came highly recommended, but the thermal expansion was much greater than the tool steel it was to seal. It invariably buckled out of its groove and jammed. Silicone elastomer did the trick.
Pete Keillor
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I've never seen black teflon, although it probably exists. I have seen UHMW in all colors of the rainbow. Both black and white are very common. UHMW is a similar to teflon but not identical.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Oct 2005 18:28:57 -0700, Jon Anderson

Sounds like graphite impregnated Teflon to me. I used some on a rotary airlock once. A local gasket house was able to pour some to our specifications.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Could be Black Nylatron.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Ive got some Nylatron drops and I just went out and rummaged around til I found em..Looks very much like Jon described.
Gunner
Confronting Liberals with the facts of reality is very much akin to clubbing baby seals. It gets boring after a while, but because Liberals are so stupid it is easy work." Steven M. Barry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have some rod sold locally as "machineable nylon". It's black, and looks like the stuff described in the original post.
Steve R.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I doubt it. Nylatron machines smooth without the tearing noted by the original poster.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook/index.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Oct 2005 18:28:57 -0700, Jon Anderson

Vesconite ????
http://www.vesconite.com/prod/vesconite.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bill Bryden posted this on an underwater ROV group.
Thought I would pass it along.
DOC
There are several simple tests that can be performed in the home that can assist in separating common plastics, however it is important to realize that formulated products contain large quantities of pigments, plasticisers, and fillers that can dramatically alter the following properties. If possible repeat the tests on a reference sample of the plastic so you get a good feel for the test and can compare directly.
a. Visually examine the sample, looking for recycle codes :-) While you are at it, you can check for indications of how the plastic was made - molded, injected, rolled, machined etc. b. Try assessing the flexibility by bending, and look at the bending zone - does the material stretch or is it brittle? c. Test the hardness, try scratching it with pencils of differing hardness ( B,HB,1-6H ) to ascertain which causes a scratch in the plastic. Alternatively, attempt to scuff the sample with a fingernail. d. Cut a small slither with a sharp knife. Does the sample cut cleanly ( thermoplastic ) or does it crumble ( thermosetting )? e. Hold sample in small flame, note whether it burns, self-extinguishes on removal from the flame, color of the flame, and smell/acrid nature of fumes when flame is blown out (Caution - the fumes are likely to be toxic). Also attempt to press melted sample against a cold surface, and pull away - does sample easily form long threads. f. Drop onto a hard surface, does the sample "ring" or "thud"? g. Place it in water. Does it float, sink slowly, or sink rapidly? If it sinks rapidly, it is likely to be halogenated (PVC, Viton, PTFE). If it sinks slowly, possibly nylon. If it floats possibly polyethylene or polypropylene. You can ascertain the actual density by adding measured volumes of a low density solvent like methanol until the sample neither rises nor sinks.
Cutting thin slivers results in powdery chips ( thermosetting ) - carbolic smell in flame, self extinguishing = phenol formaldehyde - self extinguishing, black smoke, acrid = epoxide - fishy smell = urea formaldehyde, or melamine formaldehyde
Cutting thin slivers results in smooth sliver ( thermoplastic ) - metallic "ring", burns (styrene smell) = polystyrene (note that high impact polystyrene may not give "ring" ) - "thud", floats, hard, glossy surface, burns (paraffin wax smell) polypropylene - "thud", floats, medium-hard surface, burns (sealing wax smell) high density polyethylene - "thud", floats, soft surface, burns (paraffin wax smell) = low density polyethylene - "thud", sinks, burns (fruity smell ) = acrylic - "thud", sinks, burns (burning paper smell ) = cellulose acetate or propionate. - "thud", sinks, burns ( rancid butter smell ) = cellulose acetate butyrate - "thud", sinks, difficult to ignite ( greenish tinge ) = PVC - "thud", sinks, difficult to ignite ( yellow color, formaldehyde smell ) = polyacetal - "thud", sinks, difficult to ignite ( yellow color, weak smell ), draws into long threads = Nylon - "thud", sinks, difficult to ignite (minimal flame, decomposition but no charring), cellular structure forms = polycarbonate.
What do the plastics recycling codes mean?
The recycle codes for plastics are currently being reviewed, and new codes (probably inside a totally different symbol ) will probably be introduced at some point.
1 = PET 2 = High density polyethylene 3 = Vinyl 4 = Low density polyethylene 5 = Polypropylene 6 = Polystyrene 7 = Others, including multi-layer
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 08 Oct 2005 18:28:57 -0700, Jon Anderson

Jon,     Is it machined or molded? If molded, cut a small sliver and burn it to see if it smells like candle wax. If so, it could be molded UHMW from Diversified Plastics in Missoula, MT. They grind a variety of UHMW products and mold into a variety of parts and look very much like your description. Good luck.
Tom..............
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tom wrote:

Both bushings are machined. I've compared to MDS, UHMW, and virgin Teflon. Teflon is by far the closest match. Did find a company, Enflo, late last night. They sell PTFE filled with a variety of substances, including both carbon and graphite. I'm leaning towards graphite now that I know it's available, just need to determine the % fill.
Thanks,
Jon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.