CHINESE
New Bright Carbon Fiber Products Co., Ltd
Manufacture of carbon fiber parts for "Wet"
Since mid-2006 all of our competition robots use carbon fiber as a fundamental part of its structure. We have used tissue and / or carbon tape pre-impregnated with epoxy resin that children cut and stacked to get the pieces to the desired shape. The final process of "curing" of the resin was always done outside the classroom into a laboratory for manufacturing composite parts.
This time we have faced a different challenge: carbon manufacturing a complex geometry using dry carbon fabric previously impregnate with epoxy resin. The result you can see it below.
Since our goal is to make the entire process of manufacturing carbon piece in our classroom, we have prepared a heated metal base to effect cure of it while "compact it" the piece with a bomb and a corresponding bag vacuum.
Once cleaned and degreased the surface of the metal base put a few pieces of tape sealant that will serve us to close the vacuum bag.
To prevent the workpiece sticking to the metal base placed a piece of plastic that can support desmoldeante curing temperature (about 120 ° C).
Put our piece mold which has been previously treated with any release agent (liquid, wax, tape ...).
Then cut a piece of carbon cloth enough to corcar the layers needed to make our piece.
On a thin plastic with wide tape marked the limits of our carbon piece, this will help us to spread the resin on the appropriate surface.
Mix the two components of the resin in proportions that indicates the manufacturer. The ideal goal would be to ensure that the final material had a 70% fiber and 30% resin, but this process often fabricaciíon we must conform with 60% fiber and 40% resin.
With a spatula, extend the resin on the surface of the plastic have limited with tape.
Having gained a layer of resin homogeneous place the piece of carbon cloth on it (being careful not to deform) and immediately put a piece of plastic over the fabric. With the aid of a roller we are getting the resin "soak" carbon tissue.
With the help of a template mark the different layers of our piece then cut with scissors or a "cuter".
Once the fabric pieces cut carbon let go of the one of the plastics to be placed on the mold surface.
We now see the first problems: The weight of the fabric (about 300gr/m2) is high and thick fibers have a tendency to try to cover up when suprficies curves. In addition to the piece cut some fibers are torn rather than cut.
Continue the process with the rest of the layers.
Taking special care to force the "cuter" to avoid starting more fibers.
Once cut to the welding remove fibers that are still engaged and not forming part of the carbon piece.
Once you've finished stacking the layers of the piece we put a piece of plastic mold release on it and cover with "tissue respirator" to get a better vacuum.
We placed inside the vacuum valve on a piece of tissue respirator removed the protective sealing tape our hot plate and cover the piece with the "vacuum bag".
Connect the vacuum pump to ensure that the bag closes properly (which does not) so we have to open and place the bag and the best "breathing tissue."
Once solved the problem of the vacuum bag connected to the heating plate, with the aid of a controller and a thermocouple, we ensure reasonably stable temperature of about 120 ° C.
About three hours after the piece is ready.
Given the mass of the mold, the piece remained warm for a long time to accelerate the cooling process improvised this cooling mechanism with some aluminum sheets strategically placed on the mold.
In spite of the release agent left no part of the mold, so we resorted to the technique of cooling the mold in the freezer for a few hours so that in this way the metal contraction (greater than that of carbon), we help to take off the piece.
After removal of excess resin residue (with a hand mill type "dremel") this is the look that showed our first piece made with the technique of "wet".
