Talk Composites - The Forum for Advanced Composites

coating a foam mold

http://www.talkcomposites.com/Topic30579.aspx

By spr11 - 10/3/2018 9:30:08 PM

Hi,

I want to utilize a cnc to make a mold from Foamular board or expanded polysterene.  I am looking for suggestions to coat the foam after machining so i can utilize the machined foam as a mold.  I have messed around a bit with the board and acetone melts the foam.
any suggestions?
Thanks,
Scott
By Fasta - 10/4/2018 3:03:35 AM

spr11 - 10/3/2018 9:30:08 PM
Hi,

I want to utilize a cnc to make a mold from Foamular board or expanded polysterene.  I am looking for suggestions to coat the foam after machining so i can utilize the machined foam as a mold.  I have messed around a bit with the board and acetone melts the foam.
any suggestions?
Thanks,
Scott

One method is add a light layer of fibreglass cloth with epoxy resin over the foam surface first. The epoxy resin do not attack these foams.
Then you can add more coats of a suitable primer or resin to sand a better finish with and then you can mould from this. All depends on the details involved.

Another method is where you could add a thick coat of a tooling paste resin to the foam that can then also be CNC machined. You just need to CNC the original foam design a fraction smaller to allow for some paste thickness. Use epoxies or other that are safe with the foam.
By Warren (Staff) - 10/4/2018 8:21:10 AM

Fasta is spot on with this one. The layer of fibreglass will give it a good degree of toughness making it harder to accidentally press through the thin layer of resin.