Laminate Sample #5: Vacuum Bagged Wet-layup Carbon/E-Glass with Foam Core

[@aidano5887]

I would say that the dry spots mainly come from the air sucked out from the foam core, if the core is previously sealed and there are no leaks, you can vacuum as much as you can and even had external extra preasure (autoclave), no air will come to replace the resin, no dry spots.

[@ExploreComposites]

You may be right - it was more dry than I expected. Possible the glass never got wet out completely, and also looks terrible backed up by the black carbon - everything shows!

[@nicholasvangreat260]

Hello, my question is what is meant by sealing previously the foam core? I am trying to do the same for a large project. Can it be done without excessive epoxy bleed-out?

[@themadscotsman2159]

You make it look so easy but every time I try this kind of work with glass or carbon I end up sticking to everything, Definitely going to try your techniques, thanks for a great video.

[@ExploreComposites]

Thanks! And don't worry - I make tons of messes too! Been 15 years or so of doing this professionally so I like to think I have learned something - but it's always a challenge to keep things organized and avoid surprises. Not everything I do in these laminate samples is "best practices" but I try to point out common mistakes by demonstrating - like the over-bleeding of the resin here. The idea is to show a type of laminate, but also to show how to dodge some of the more common issues. Hoping some day I'll have the time to make some more detailed how-to videos...

[@themadscotsman2159]

@@ExploreComposites Thanks, I've learned a lot without getting my hands dirty so far or wasting materials with trial and error. Once I have all my materials and the weather is warm enough I'm gonna have a go at making some carbon panels.

[@kennneee1]

I have a moderately complex shape epoxy layup using 2 layers of 5.8oz CF and 1 layer of 6 oz E glass. I was planning to use peel ply and breather before bagging. I see that you are using a perforated layer as well. Is that necessary? What vacuum pressure is appropriate. Thanks for the great videos. Very helpful to a newbie to this process.

[@ExploreComposites]

Almost always it is best to use a perforated release film. Without it you will suck out too much resin and make removing the breather very difficult - like no fun at all! You can make perforated release film by folding up thin painters plastic and punching small holes every 2” / 50mm or so. Its not as good as the actual product buy WAY better than nothing!

[@ExploreComposites]

Vacuum for wet bagging - about 15inHg or half of full vacuum is a good place to start.

[@BBBA_]

What are the fabrics being layed on ??

[@js800]

How did air get in the part (porsitsuty) if you pulled the air out with the vacuum? Hole in the bag?

[@ExploreComposites]

There is air mixed in with the resin when hand wetting-out and I am quite sure the glass wasn't 100% saturated. Ideally the compression of the bag will force most of the air out, but a bagged wet layup will always have a much higher void content than infused or pre-preg. This was an issue of not being able to get air out, rather than having air leaking in... either way not great!

[@wouterhendriksen4099]

@ExploreComposites how do you estimate core bonding resin uptake of the foam? cant seem to figure it out

[@ExploreComposites]

You really have to test to be sure, but estimating the volume of perforations and flow grooves is pretty easy if you measure with a caliper and do lots of multiplication. Plain foam surfaces take up resin inversely proportional to density of the foam because high density core has smaller cells. Nothing like a few square meters of test panel to get it figured pretty well including surface flow and feed lines.

[@laptopasus4788]

what type of foam did you use, why doesn't it melt when exposed to the resin?

[@ExploreComposites]

This is a Corecell SAN foam made by Gurit - it is designed to work with the resin and not melt. EPS foam will be "melted" by the styrene in polyester and vinyl ester resins.

[@nicholasvangreat260]

This is exactly what I am planning on doing. What bagging material and vacuum pump would you use to do it on a 14’x10’ sandwich panel? Also, why did you mix fiberglass with carbon glass - don’t they have different structural properties and one would affect the other?

[@ExploreComposites]

A panel that size should be doable with even a very small pump... as long as you don’t have leaks! Bigger pumps just get it done quicker and higher pump volume makes leaks easier to find. The glass and carbon here are pointing in different directions which is common - adding carbon uni to a glass laminate for local reinforcement. If glass and carbon are together pointing the same way the stiffer carbon will take up all the load and the glass will be redundant. Also here it made it easier to see the over-bleed because of the contrast.

[@ИванИванов-м6ч1о]

Does the shown lack of resin strongly affect the strength of the panel only in compression or also in tension and shear?

[@ExploreComposites]

I'm not sure without testing. It probably does to a degree and as you suggest - more in compression. Shear - no idea! I'm sure people have done tests and I'm pretty sure I've seen graphs of mechanical properties vs. resin but it's pretty laminate specific and core makes it weird. Wish I was an engineer!

[@qcnck2776]

Thanks for doing these videos. What is the material of the mold surface/table that you place the fabric on?

[@ExploreComposites]

The table has an adhesive PTFE release film. Made a video about it here: kzbin.info/www/bejne/h4e7c6KghdGXr7s

[@qcnck2776]

@@ExploreComposites Thanks :)

[@saerhoga7643]

Super Good.

[@ExploreComposites]

Thanks!