Wet layup "ish" ? Your thoughts...

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#1

Hello Expert Composite Technicians!

I had a question with regards to production. I was wondering if any of you guys had tried this technique in a “production” type application:

Airtac2 (or any composite fabric adhesive) the carbon into correct position, detail, and orientation on the mold, then wet the fabric out. So in theory your doing a “wet layup” with the exception that you’re wetting out the ply once in the mold, rather than on the work table and transfering the wetted material to the mold.

Any problems with getting the resin to the mold surface? Some pinholes are acceptable as the end item will be automotive UV clear coated.

Layup:
Ply 1. 3k 282 Plain Weave Carbon 0*
Ply 2. 3k 282 Plain Weave Carbon +45*

No Infusion or vacuum bagging… just raw material, resin, and room temp cure.

What are your thoughts?

-C

#2

I would think that getting the fabric adequately saturated would be a problem. Also the resin may break-down the Airtac causing the fabric to release from the mold before the resin sets.

You could always just layup an intricate portion of the mold and see what happens.

#3

What you described is a very common lamination method. Dry fabrics are placed in the mold and then wet out. It is helpful to “back wet” by first spraying resin onto the mold surface and then lay the dry fabric onto the wet surface and then roll out any air, more resin can be sprayed onto the surface if required. There is no need for using double sided tape since the resin helps the fabric stick to the mold surface.

#4

If the job is not being infused, I would have thought that you would just put down resin on the mould, then that will hold the fabric? Isn’t spray adhesive only used when you don’t have the ability of using resin to hold the fabric?

Also depending on how big/complex the part is, you may benefit from doing your own pre-preg? Obviously on a smaller sheet size, maybe slow hardener will give you enough time?

[ame=“http://www.youtube.com/watch?v=9_tDQTgdsCg”]DIY Carbon Fiber Prepreg. How to Make Your Own Pre Preg Carbon Fiber - YouTube[/ame]

Of course I am yet to do my own test pieces with CF, so I don’t have any real experience at this - just throwing ideas out there!

#5

Thanks guys for your replies… I greatly appreciate it!

WyoWind,
I did a small test (emphasis on small) and it seemed to wet out, but I didn’t want to waste material on a larger actual production piece without hearing the experts on the forum first. I didn’t use any part of an intricate mold to do the test, so I wasn’t able to see if the Airtac2 dissolved or not.

Infusible,
Good to hear your reply… wet layup isn’t really normal practice for my business but in the past if I ever had to… I’d always wet the ply then put it in the mold. Unfortunately this new upcoming piece has some details that are very aesthetically critical and applying the carbon wet isn’t an option. I’ll maybe try ditching the Airtac2 for this one any try out your suggestion with regards to applying a thin layer of resin to the mold surface, thus creating a good finish surface and providing an adhesive for the fabric to cling to during the lamination.

Mugget,
I’ve never used resin to hold the fabric to the mold… Infusible from above mentioned that technique also. I think I’m going to have to try that out. Nice video you found, I remember reading a different post here on this forum recently with regards to the difference between “resin” and “pre-preg resin” as there is some sort of potential resin mix out time situation that could arise. Never the less, it would be interesting to make a pre-preg for non bagged room temp cure, I wonder if the outcome would be the same as if I had normally wet out the ply, but being pre-preg, allow me the opportunity to control the details of the fabric.

Thanks again guys, your suggestions, insights, and help are really fantastic!

-C