Polishing UHMW
Polishing UHMW
(OP)
Hi,
Can anyone recommend a polish/technique to get a very smooth surface on a UHMW? Ideally something easily obtainable and not requiring a particular skill.
The part is a mold and I'm hoping a smoother surface will improve release of shore A 40 silicone parts. Currently the surface has machining and sanding marks in it and it's not releasing even with various mold release agents.
Thanks!
Jon C.
Can anyone recommend a polish/technique to get a very smooth surface on a UHMW? Ideally something easily obtainable and not requiring a particular skill.
The part is a mold and I'm hoping a smoother surface will improve release of shore A 40 silicone parts. Currently the surface has machining and sanding marks in it and it's not releasing even with various mold release agents.
Thanks!
Jon C.





RE: Polishing UHMW
RE: Polishing UHMW
Is it an open (split) cavity?
The finishing process will be determined or restricted by accessibility to the cavity surface.
RE: Polishing UHMW
RE: Polishing UHMW
RE: Polishing UHMW
You can waste a lot of money trying, of course.
Instead, spend the money polishing the tools that cut the cavity, bring their edges to razor sharpness, and never use them to cut anything else.
Then machine the cavity in a few passes, with the last/finish pass being not less than .003" (or maybe .005" or even .010", depending on the material particulars).
I.e., you can't sneak up on the size you want in UHMWPE, with skim cuts or abrasives; you have to cut right to size while producing a chip that is fairly strong and thick.
Mike Halloran
Pembroke Pines, FL, USA
RE: Polishing UHMW
http://www.connecticutplastics.com/qa/plastic-poli...
"I have a transfer mold for pulp & paper that requires a smooth finish to prevent sticking. The material is white UHMW. Is this material suitable for polishing? If not, can you recommend another material?
UHMW can be polished through buffing. Depending on the plastic part configuration, we can achieve a high finish."
Now how well it works is another issue and I am not making any claims about that, but this is your best bet. Before scrapping the mold and making a new one, it is worth a shot to take an angle grinder with a buffing wheel to it.
One more off the cuff suggestion, buff it with oil in an attempt to impregnate the plastic slightly. Probably won't work all that well but again, could be worth a shot.
RE: Polishing UHMW
I managed to get a nice shine on a small test area using 600 thru 1500 wet sanding then coarse and fine acrylic 'scratch remover' polishes followed by red rouge on a drimmel tool. Lots of labour :/
Has anyone actually tried flame polishing UHMW? I've heard it's quite easy to damage/oxidise the surface by going just a few degress beyond melting point.
RE: Polishing UHMW
You wouldn't have to use an actual flame. Other heat sources would also work, and may be more controllable.
RE: Polishing UHMW
I guess I'll experiment with a heat gun on some samples..
RE: Polishing UHMW
RE: Polishing UHMW
I have no idea if UHMW can be melted and remolded, and then retain all of its original properties.
Joe Dunfee
RE: Polishing UHMW
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Polishing UHMW
FYI UHMW is machinable, about as slippery as teflon and one of the cheapest plastics out there (1/4 the cost of aluminum(?)).
So..it seems a flame is all that's left to try (or possibly a really hot heat gun?). Any ideas on what type of flame?
RE: Polishing UHMW