Help on Plastics Finish
‎Aug 26, 2014
06:35 AM
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‎Aug 26, 2014
06:35 AM
Help on Plastics Finish
Hello,
I don't have much experience with plastics, so I am looking for advice.
I have a part machined from a piece of polycarbonate. I want the surface finish to be good enough that it looks clear, not translucent - almost glass-like.
How do I specify that finish on a drawing? I imagine I need a symbol to machine it all over, but what roughness value corresponds to the kind of finish I am referring to?
Thanks for your help.
Cheers,
John
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Surfacing
2 REPLIES 2
‎Aug 26, 2014
08:44 AM
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‎Aug 26, 2014
08:44 AM
John,
Machining PC will leave the surface (and the part) "frosted" and thus
translucent - not transparent. The methods for getting the machined surface
back to a transparent state involve either reflowing the surface (with
chemical or heat) or high polish. Much cheaper results can be achieved with
a clear coat of spray paint - but this will not be a perfectly clear - nor
smooth - finished surface and it will not be as durable. This latter method
I have used a lot with SLA parts that need to appear as PC or glass. It
does give a really nice looking "clear" part. But it is far from
"optically" clear. I do not have direct experience with refinishing
machined PC to a polished condition.
So, depending on your actual needs, you have a few options. I would call
the vendor(s) and talk with them to see what they recommend. I would also
call and talk to various prototype shops to see what they would recommend
(here's a good one that I've used: Empire Prototype
Machining PC will leave the surface (and the part) "frosted" and thus
translucent - not transparent. The methods for getting the machined surface
back to a transparent state involve either reflowing the surface (with
chemical or heat) or high polish. Much cheaper results can be achieved with
a clear coat of spray paint - but this will not be a perfectly clear - nor
smooth - finished surface and it will not be as durable. This latter method
I have used a lot with SLA parts that need to appear as PC or glass. It
does give a really nice looking "clear" part. But it is far from
"optically" clear. I do not have direct experience with refinishing
machined PC to a polished condition.
So, depending on your actual needs, you have a few options. I would call
the vendor(s) and talk with them to see what they recommend. I would also
call and talk to various prototype shops to see what they would recommend
(here's a good one that I've used: Empire Prototype
‎Aug 26, 2014
12:29 PM
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‎Aug 26, 2014
12:29 PM
John Wayman,
I don't think that you can specify that as a "roughness." It would be best
to prescribe it as an operation. It would be best if you put that kind of
requirement in a note.
Michael P. Locascio
I don't think that you can specify that as a "roughness." It would be best
to prescribe it as an operation. It would be best if you put that kind of
requirement in a note.
Michael P. Locascio