Talk Composites - The Forum for Advanced Composites

Issue with hand layup carbon part

http://www.talkcomposites.com/Topic32950.aspx

By Damien - 5/26/2019 8:55:17 AM

Hello,

I have an issue with my hand layout carbon fiber parts...

It looks like the resin does not fill in the carbon part really well...see photo

Here is my process:
- Mold with gel coat and easylease release agent (I have no problem releasing the part)
- Temperature 23-25 C
- This part (but I get the same with all parts) is 1 carbon  (1st layer) and 3 glass
- I use a 1.3:1 in weight for the amount of epoxy vs material
- I use the easycomposite roller to remove air bubbles etc...at each layer. This time, even, to try and see if it would help, I used a heat gun on each layer to get rid of micro-bubbles. But made no difference.
- Then I put a release tissue, a perforated film and a layer of special
foam to absorb the excess of epoxy.

- Vacuum bagging overnight

But still I get this...which gives me lots of work to give it a proper finish afterwards...

Any idea what I do wrong ?

Thanks !
By JasonFL - 5/27/2019 3:22:32 PM

For wet bagging your resin should equal the amount of cloth. If your cloth weighs 1000 grams then you should mix an equal amount of epoxy. Too much resin will cause the excess resin to shrink between the tows. Can also float the bag in areas.

Apply all of your resin to your plys except for the very last ply, putting the last ply on dry will pull air and resin towards the top ply and it will completely wet out once under vacuum.

Using perforated release film is almost a must. If you do peel ply and breather you will starve your part of resin and possibly lose vacuum in wet areas. If post bonding isn’t needed don’t use peel ply at all and stick with perforated film.

Also if this is a flat part consider a kaul plate. You can make your own out of silicone.

This still won’t cure your issues but it will help quite a bit.