Glossy surface, no voids, no air bubbles but...

General Composites Discussions Composites Talk
#1

Hey guys, I cant go ahead with one problem , I infuse my parts everything is good quality , I cure them in oven but my finished surface has signs of carbon fiber… Is it possible to fight against this without using gelcoat?

Last time for instance when I used lantor soric on flat sheet it also could be seen in some angles on finished product… I could even feel it under my fingers

The funny thing its not seen in photos.

I start to think that this issue is the biggest disadvantage of using infusion process.

Whats your ideas?

Its little seen where the light drops

#2

are you post curing in mould or free standing? Usually surface print is less than if free standing.

#3

right after its infused it lands with mould ( on glass) to oven for 4hours 50*celcius degrees

#4

there is always surface print in parts that have no surface coating. if you use a IMC this will lower the amount of print as it puts the fiber further from the surface, but more it gives you a good surface to polish after post cure.

#5

Yes I use IMC also , but Im curious if its possible to get nice surface without gelcoats and IMC?!? btw with IMC also prints happened.

#6

Yea, I think that the surface would look basically the same. I usually only use IMC for two reasons, one you can polish after easy and remove fiber print, two it was a good interface between the tool and the epoxy resin. Mould maintenance was less

#7

What kind of resin? You might consider slowing down your curing process. Print-thru is reduced by reducing resin shrinkage. Rapidly curing the resin by immediately applying heat can increase the shrinkage of some resins. Also, your soak time my not be long enough to fully cure the resin before you are demolding.

#8

Its called LG700 , hmm you might be right , Im putting it toward 50 celcius degrees right after its infused, and cook for about 4 hours.

I’ll try starting at 40* and slowly ramp up

btw did you test how act IMC in higher temperatures like 60-70 celcius degrees?

#9

I’d try letting the resin set at room temp and then post cure the resin while the part is still in the mold. It may or may not help. Often the components in low viscosity RTM resins will increase the shrinkage of the resin. There are probably some resins that are less prone to shrinking.

I have never cured a urethane based IMC past 55*C. It might work just fine. I’ve just never gone past that. An IMC probably won’t resolve the problem.