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Chopped carbon fiber, vacuum bagging?

http://www.talkcomposites.com/Topic37886.aspx

By Kacordy - 9/14/2020 2:38:32 AM

Can I sprinkle 1/4 chopped CF down the center of a complex part to mask the seam of 2 pieces of Kevlar/CF that I will use as a surface veil?  I would sprinkle the 1/4 CF to create a 2 inch wide 2 foot long center stripe. Will the infusion epoxy flow through this 2 inch strip? Or will the Chopped CF move. I don’t think it will move because of the layers I will have on top to strengthen the part. I’m talking about doing all this dry, not a wet lay-up. Thanks, Allen 
By Kacordy - 9/15/2020 1:56:53 AM

 
Kacordy - 9/14/2020 3:17:53 PM
 
Hanaldo - 9/14/2020 3:49:38 AM
Yeh no problem at all. You can infuse virtually anything you like.

I'd recommend using some spray adhesive to hold the chopped fibres roughly where you put them. If it were me, I would mask off the 2" strip, put a little bit of spray adhesive down, sprinkle some chopped tows on there, spray a bit more adhesive, repeat until you're happy with the coverage. Otherwise, if you leave them loose - static is going to wreak havoc when you place the woven materials. 

Thank you  for the replies. I will post some pictures tonight  and give updates as the project goes along. This is all new to me. I have many projects planned. Allen



Here is a picture of my very first mould with Orange tooling Gel and 15% Duratec Clear Hi Gloss.  This is a cowling for a 48inch Gas RC boat. The Kevlar/CF cloth to the left is what I want to use for the surface veil. The panel to the right is my very first test of all my new vacuum bagging equipment. It ended up showing the grain of the Kevlar and has checks in the cloth. It does not have the beautiful deep clear finish. I clamped off the resin and continued to pull Vac for awhile so I believe I pulled out to much resin. Back to my original post on the CF chopped strand. If you look closely at cowl I added an air Scoop. The purpose is not for an air inlet but to cover the spark plug. I will cut out the other vents you can see for the air intakes and exits. My challenge is the deep pocket of that air scoop. If I lay down a dry full Kevlar laminate, it will get distorted trying to fill the scoop pocket. So my thought was to run a chopped CF fiber down the center of the cowl so I can split the Kevlar panel into 2 pieces and the chopped CF would mask the seam. By also laying the chopped to cover the pocket I can cut small pieces of CF or E-glass to layer up the pocket. If I layer and lightly use 3M Hi-Tack 71 as I layer my dry layup, I believe everything will stay in place when I pull vacuum and infuse the layers. I’m using Pro-Set INF-114 infusion resin and 211 medium hardener. Thank you for the suggestions, Allen