sticking down carbon cloth!

What can I use to stick down carbon cloth to the mould to hold it in place? I am using epoxy resin! I want to hold the cloth tight to the mould so I down get bridging. Thanks!

 

There is a spray on glue on the market, ask your glass / carbon supplier. I have forgotten the name (if I ever did know).

Regards
Richard

 

Epoxy is fine but you have to vacuum for best bonding.

 

Not really.

Epoxy is not only fine, it is the only sensible material. And of course the bond is not the reason for bagging, the lower resin content is.

But that was not the question, the "stickum" is.

Regards
Richard

 

3M-77 or similar will do, but use very lightly and let it flash off for a minute before applying the carbon.

 

Sorry I dont mean I am using epoxy as a glue I ment I am using epoxy resin with the carbon. I am using the resin infusion method but need a way of holding the cloth in place. So it looks like 3m 77 is the way forward! Does it affect the finish or the part?

 

It doesn't effect the bond, if used lightly, but I've never used it in a mold. Maybe the composite builders can chime in with the techniques they use.

 

...no, it seems to have no affect to the finished job, but speaking only from vinylester resin use, not epoxy, though it is my belief that the same applies, as many people I speak with use epoxy all the time...Just use ya brains and not any more than is necessary..In fact it needs bugger all to hold the cloth.

 

Not knowing the 3M stuff Paul mentioned, but I know we use some spray on stuff to hold the first layer of overhead jobs in place before wetting out.

Herman recently mentioned something similar for a infusion job, but I do not remember when, where and what. (just not my world).

Give Herman a PM to know more (much more) about infusion tricks.

Regards
Richard

edit: "Epok Z" is the goo, my production manager told me! It becomes part of the matrix, crosslinking with the resin.

 

3M-77 spray is what I use for over head work on the usual fabrics, but I have to admit a lack of experience with carbon inside a mold and if the 3M 77 affects the look. John says no, so that's good enough for me. My carbon work is almost always around a mandrel or over a male form, no need to "stick" it.

 

If you like to stick fabric in a mould, there is the challenge of the mould being slippery. There are 3 options:

-hold the first layer of fabric (carbon, glass, whatever) mechanically in position at the sides.
-use a gelcoat, wait for it to cure into a sticky layer, and position your fabric into that (hardly a possibility to re-position the fabric, when it is a fine weave. (CSM will be no problem, but that was not the question here)
-use spray glue. This, used on the mould side, will leave marks on the surface, however. (even the so-called cross linking ones). For visually demanding parts this is not an option either.

With the gelcoat option you will also need to take into account the overcoat window of the gelcoat. (whether epoxy or polyester based). Do not wait for days before infusing.

What you can do at least is position your first layer dry, and lightly spray glue the next layer onto that. Position into place using a HDPE "paddle", a flat and rounded piece of plastic. With subsequent layers the part will become stiffer, and hold its shape.

Another option is to lay all fabric dry, apply a vacuum (very low) and aggressively position with the same tool. (using no glue makes the cabric able to slide over each other, but use a very, very light vacuum, then gradually increase.

Some mould shapes can be a pig to get the fabric in very well. Prefilling of a difficult part sometimes works as well.

Spray glue:

Ce-Sense Resin Infusion Spray Glue (www.brandscomposiet.nl, introduction at METS 2010, I have a university report on ILSS strength, which does not suffer from using this glue)
Airtac 2 (www.airtechonline.com)
NG-IF (www.northstarchemicals.com)
3M 77 (www.mmm.com)

In any case: Use spray glue sparingly and lightly. It is something you actually never want in your part.

 

Here use this:http://www.ok2spray.com/specialty.php

I would gelcoat and skin the part out then gradually debulk ,massaging the laminate in place on a slow draw down maybe stopping at a low vacuum level and double checking all inside corner surfaces to make sure the laminate is seated..

 

I would spray Clear Polyester gelcoat and infuse with polyester or Vinyl Ester resin , It will go off faster and remain clear under all circumstances unlike Epoxy which is slow to cure and can amine blush with Humidity , Epoxy resin is also likely to yellow with UV.

ps I have seen Infuzene (spelling?) Is available in the US which appears to dissolve in styrene and not affect the finished styrenated laminate at all.

 

We make tackifiers for both Epoxy and polyester & VE to hold fabric in place that do not compromise the laminate like the spray glues can.

What we've seen in our testing is the spray glues can be OK structurally if only the minimal amount is applied, but they may still have problems with cosmetics when used too near the gel coat even at the low levels. Apply more than the minimal amount and both the Physical and cosmetic properties drop off quickly. This is where the problems start, many times far too much is applied while loading the tool, either on purpose or by mistake and the quality of the part suffers.

In the aerospace market you can be fired for even picking up a can of spray glue, it is strictly forbidden in most shops because of what it can do to a laminate.

 

Poly with carbon? A bit uncommon mix, isn´t it?