Talk Composites - The Forum for Advanced Composites

Hand Layup + Vacuum Bagging Techniques (doubts )

http://www.talkcomposites.com/Topic25442.aspx

By Dezer - 3/16/2018 10:56:07 AM

Hello Friends, 

I'm making some parts in carbon fiber (aesthetics) and I know that for this type of product we have some particularities in the manufacturing process. 
Using 3 layers of carbon fiber and epoxy resin with gel time of 290 minutes and pot life of 120 minutes.

My doubts are as follows:

- What's the ideal time to apply the vacuum in my laminate?

- How long should the part stay in the vacuum connected?

A friend told me that for aesthetic parts the ideal would be for me to apply the vacuum a little before the gel time of the resin and for being close to the gel time I can use vacuum above 600 mmHg.

Can anyone help me with this question?

My main problems with Wet Layup + Vacuum Bag were:

Dry parts: - Excessive vacuum or vacuum at the wrong time.

Bubbles / Bridges: Vacuum at the wrong time where the resin was already in the gel time, so the vacuum could not remove them.


Thanks Guys!!
By Steve Broad - 4/27/2018 11:21:53 PM

 
Hanaldo - 4/26/2018 11:07:06 PM
 
Steve Broad - 4/26/2018 10:27:27 PM
20% vacuum? How do you achieve that? I thought the perforated peel ply regulated the resin content?

Preparing to be educated :-)

The release film can only do so much, at the end of the day it is just holes in a piece of plastic. How much resin comes through those holes depends on resin viscosity and vac pressure.

Ideally you would regulate the pressure with a vacuum regulator, as this allows you to set a precise level as well as keep the vacuum pump running until cure. Otherwise, if you have a perfectly sealed bag then you can simply pull vacuum and use a gauge to get to approximately 20% or whatever you are aiming for, and then just clamp it up and leave it. Obviously if you have a leak then this doesn't work, which is why having a regulator is an advantage.

Thanks