Optic Clear Finish in Polycarbonate

[crazy^millman]

I have this part that is about 3/4 x 1/2 about .063 in thicnkess with some very carzt details. They want me to polish the machined out surface to a Optic Clear finish any ideas. I can not clear coat it cuase it has have some crazy coating applied to it. It it where freaking cold rolled to Titaium no problem but not had much luekc polisihing this material and hold a tolerance for an optical surface.

 

Crazy Millman

[Rekd™]

Heh, fun stuff. That's where I cut my teeth in machining, plastics.

 

There's a few options here. Hand polishing. (Yeah, right) Flame Polishing. (Using hydrogen/oxy) Chem Polishing. (Don't know how/what this is exactally, but you're supposed to be able to dunk yer parts in a solution and it comes out polished nicely.) Vapor Honing. (Bead blasting with like baby powder or flour type media)

 

Sometimes you can get a somewhat polished surface via machining. May take a while on 3d stuff though.

 

HTH

 

'Rekd

[Roger Peterson]

Vapor polishing

 

 

There is also acrylic glue. It is very watery and it melts acrylic or polycarb and leaves a nice clear finish after it's been brushed on then let dry. It doesn't add "thickness" to your part it basically "melts" it.

 

 

HTH

[crazy^millman]

Yeah but my concern with that is it leave solvent on the part and this is going in a medical application so the part had t obe like FDA acceptable. I have polished dow nas far as 1500 grit on poly and still not get it to do a optical finish. I have also use buffing compound and found a buffing wheel does ok but destorts the part. I guess I will have to make a mold and shoot it. Ok well such is life just another thing they want tommorrow.

 

CRazy millman feel that ton rock on his back get alittle more added to it.

[the1yyz]

You may be able to call some at Harrington plastics or Ridout, Ryan Herco or any of the plastics suppliers for the proper solvent to use in this type of application.

 

Also some of the chemical supply houses might be helpful also.

Crown Chemical, Baker Bros.

[Rekd™]

quote:

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Ridout

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Bah. I used to work for Jack Ridout. He's almost as much of a schiester(sp) as Gray Dufis..

 

Good suggestions, though..

 

'Rekd

[Scott Bond]

Would it be possible to simply use a buff wheel on it?

EDIT

Posthaste, I misssed your post that mentioned the buffing

 

[ 10-08-2003, 03:48 PM: Message edited by: Scott Bond ]

[Keith Graydon]

quote:

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Yeah but my concern with that is it leave solvent on the part

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Go the chem/solvent route. The solvent will evaporate. Flame polishing works well with acrylic but is a little(lot) tricky with polycarbonate. It will also distort your part. Try to minimize your toolmarks first. Less to polish.

 

HTH

-KLG

[Roger Peterson]

The chemicals work great, and was said above they evaporate. Vapor polishing uses a chemical vapor anyway, it works great but spendy. Depending on your setup you may get it clear enough just by using coolant. If you are using a vacuum chuck misting works good enough. This is also very thin material, are you simply profiling it? If so send it out to be lasered.

 

 

HTH

[George_Gerhard]

Millman

Onsrud makes excellent tools for machining plastics tool #60-249 is a three flute finisher which will give you a nice pocket. I have my customers run this tool at 15,000 rpm and 200 ipm

There is another tool the number I cannot recall exactly but I think it is 57-360. I have used that tool on solid surface material.

Another trick (and it works) is to use transmission fluid, as a lubricant/cooling agent

 

regards

George

[crazy^millman]

Well good news my customer came back and said i could make it out of acrlyic so all is solved from there I know how to make it optical appericate all the tips guy will ekkp them in mind in the furture thanks.

 

 

Crazy Millman