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Nerd Lab - 8/3/2018 4:46:23 AM

We are casting a complex part with a lot of sharp and opposing angles, which has proven to be extremely difficult to accomplish with a single sheet layup. While we did close in on the goal, the method proved to be unsound. Changing methods, the best results have come from approaching the layup with multiple carbon fiber pieces. This required a lot of precise cuts and matching of weave, as you might imagine. The problem now is that we get stray, quite noticeable, carbon fiber 'fragments' in our parts. My question is to know if there is a way to apply some type of temporary backing to a section of non-prepreg roll which would keep the weave intact to allow me to cut and lay out the shapes I need and reduce stray fragments, then being able to peel off the backing upon layup.
There is one YouTube video of an Aussie showing how to apply a mix of PVA/H2O and thin 'paper' which dried as a backing which you can then peel off in layup. That didn't work for us. Is prepreg the only answer? I would also think that since we're spraying clear gel coat in the mold before layup, any PVA would ruin the bond between the resin and gel coat. Is there a resin soluble product that we could bond the carbon fiber and paper with? We also use spray adhesive to keep a couple of key parts in place which claims to dissolve in resin but that seems to risky.

The templates in the picture attached are a few of the shapes that we need perfect.
Thanks for any help,
Sr. Nerd Lab Technician 

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Hanaldo - 8/3/2018 10:24:16 PM

This will cause interlaminar bond issues ^ There are tapes made specifically for this like Airtech Airhold, but they are expensive and not really that useful.


The 'web-lock' brand of set-weave carbon you can get from Composite Envisions. I've heard good things about it compared to other set-weave fabrics, and it's like the Toray version - much softer than the others and uses a hot melt binder rather than the b-staged epoxy.

You don't really need it though, and you don't need an especially flexible fabric to tack to the back of your carbon, just tack two layers of carbon together. If you need more drape or conformability, cut the second layer so that the fibres are at 45 degrees - I find this is very rarely necessary.