Chemical Polishing

[rfulford]

I just received an RFQ from a client that specs PETG with chemically polished edges. Chemical polishing is a new concept to me. Does anyone know how it is done and if it is a viable solution for PETG? I am sure it must involve some type of hardcore solvent.

 

[Moze]

You can wipe MEK on the edges to obtain a polished edge similar to flame polishing.

 

[letterman7]

Pretty much. You'll need a solvent that basically melts the plastic. Certainly not the easy way to do it and not the quickest, nor does it afford the crystal clear properties of a flame polish. Some good reading here - see page 3: www.eastman.com/Literature_Center/Misc/EdgePolishIAPDNov07.pdf‎

 

[John Butto]

You have to sand the edges smooth before using MEK and a retarder mixed in if needed. I prefer sanding and then polishing compound on a buffing wheel.

 

[rjssigns]

The experiences I've had with odd specs are thus. They were written by an engineer or someone that overheard the term and likes to sound smart. Now that the specs have been written and filed they are followed blindly.
Just flame polish and send it out. They'll never know the difference.

 

[rfulford]

Thanks for all the replies. I was under the impression that PETG could not be flame polished but there seems to be plenty of evidence that states otherwise. I quoted the job estimating time for flame polishing. We will see where that goes.

 

[natedawg9640]

Chemical polishing can also imply caustic gas. i.e. if you have a large quantity of plastic parts, they rack them up, put them in a chamber and flood the chamber with corrosive gas, puge, and you're left with a whole bunch of polished parts in no time flat.

 

[Techman]

the problem with flame polishing is that it creates stresses on the polished edge. It will often crack or craze especially if a solvent cleaner such as alcohol is used on the sheet. That is the problem with flame polishing..

 

[DIGIXTRA]

You can wipe MEK on the edges to obtain a polished edge similar to flame polishing.

Hi Moze,
This post is interesting to me. May I ask what is MEK stand for?
Thanks

@Letterman: The link is dead. Do you have other site that relate to this article?

 

[Hicalibersigns]

Not Moze, but I believe that it is Methyl Ethyl Ketone. Available from paint suppliers.

 

[John Butto]

If you stack the pieces together with small piece of doublestick tape, providing they have a paper backing and all the same size. Run the edges through the planer and sand with a jitterbug. Then with polishing compound and a buffing wheel you can do at least 10 (average size 8"x10"x.25") if not more at the same time.

 

[letterman7]

@Khai; that's weird. It was one of the first links in a Google search for "PETG chemical polishing". There are others, all .pdf's that won't link.

 

[Moze]

Not Moze, but I believe that it is Methyl Ethyl Ketone. Available from paint suppliers.

Yepper, can also get it from Home Depot.

 

[DIGIXTRA]

Not Moze, but I believe that it is Methyl Ethyl Ketone. Available from paint suppliers.

@ Hicalibersigns - Thank you. Have been busy lately and does not have time to check the forum..

@ also thanks Letterman7. I searched the google as per your suggestion and found quite a few sites...