How to repair a composite mold

[avior]

A carbon – epoxy mold .200” thick was donated by an aeronautical composite manufacturer (we don't know exactly what resin and tissue was used to manufacture the mold). This mold has a .250” hole machined throw. We intend to laminate few parts (8-10) from fiberglass epoxy 350F autoclave cure cycle. We can not vacuum bag the part because the mold will leak (the autoclave 90psi positive pressure will push the nitrogen under the bag).
Do you know how to repair the mold hole, on fact can you recommend a resin system and a reparation procedure to withstand 20 cure cycles (expansion – contraction) without leaking?
The parts need to be consistent because we intend to show them in a contest between university faculties . . .
Thanks.

 

[wes616]

Try high temp bondo, or fill with a resin mixture. Post cure the mold before laying up, then bag check the mold to ensure vacuum integrety. Any 350 cure wet laminating resin will do.

You may not get 20 parts out of it, without doing a second repair, but you may.

Wes C.
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[simakoffmaster]

hi guys
yesterday, going throwgh net, i saw an interesting thing

http://sotopanel.com/?page_id=15

oh,i want to know this unique method...
carbon is one of the most expensive material....

 

[avior]

But this is carbon fiber reinforcing thermoplastic resin, our mold is carbon-thermoset resin (epoxy)

 

[berkshire]

In addition to Wes C's suggestion of high temp polyester putty. I would suggest a scab patch, on the outside, of the hole in the mold, of a high temp laminating glass and resin.
The stuff you are going to use for parts should be OK for this as long as it is cured at a higher temp than your parts before you start laying up parts.
You just want a vacuum seal in case the polyester shrinks and falls out.
B.E.

 

[Compositepro]

For a 0.25" hole you can probably get away with filling it with silicone sealant. Epoxy putty will crack from cure shrinkage and thermocylcling stresses. The material in the hole will see little in terms of externally applied load its most critical function is to provide a gas tight seal.