Carbon Fiber Wet Layup Procedure

Owned by Megan Spee
Last updated: 2023-12-11 by Smile Khatri
2 min read

Surface level documentation on carbon fiber manufacturing. Please reach out to the appropriate mechanical lead or expert to instruct you with more detail before attempting.

Carbon Fiber (CF)

All composites work should take place in the composites room and using appropriate PPE

Flat Layups

If doing a flat wetlay on a glass table, clean the table using a scraper.

5 layers of mould release chalk/wax (wipe between each layer application, and let sit after application for ~5 minutes).

Layer epoxy → CF → epoxy → CF … etc. → epoxy → peel ply fabric.

  1. With a disposable brush, paint a layer of epoxy onto the surface of the mold.

  2. Place the CF piece.

  3. Paint a layer of resin on top of the CF piece.

    1. Make sure to do short brush strokes to spread out the resin followed by stippling rather than long strokes. Long strokes increases the risk of disorganizing the individual CF strands. Sometimes, bristles might fall off and get caught in the resin when doing long strokes. The goal is to push resin into the CF and long stroke won’t help achieve this because it is not effective at pushing resin into the CF.

  4. Squeegee out excess resin.

  5. Repeat steps 2-4 per each layer.

  6. After all the layers are done, place the peel ply fabric on top of the final layer.

  7. Press the peel ply fabric to make sure that it absorbs excess resin from the final layer. A squeegee will help achieve this effect.

  8. After the resin has cured, you can tear the peel ply off (it should come off pretty nicely). Use a scraper or a blade to release the edges of the wet layup.

 

General rule is weight of carbon fiber == weight of epoxy resin solution. Do not forget to tare (or subtract) the weight of the cup that holds the resin when measuring resin and hardener quantities. Also pour the resin and hardener slowly.

Aeropoxy epoxy resin solution = 100 parts epoxy, 27 parts hardener (the ratio might differ depending on the hardener and resin used so make sure to read the container label).

 

Other notes:

  • Sharp bends increase the risk of introducing air bubbles because it is more difficult to push resin into a bend. Air bubbles leads to small dents/dry spots after the epoxy cures. Air bubbles are almost unavoidable because air particles will enter the resin when you are mixing it with the hardener. Hence, one must do a good job of squeegeeing and stippling to push out the air bubbles along with excess resin.

    • To minimize air bubbles you can:

      • de-gas your resin using a vacuum chamber

      • let the epoxy mixture sit for longer after mixing (but you will need a longer epoxy pot life). After you mix epoxy resin and hardener, the bubbles that you see are air particles leaving the mixture.