Vacuum Infusion is a unique process which utilizes atmospheric pressure to push resin through a closed mold (typically with a bagging film). It works through the principles of D’Arcy’s Law. Composite laminates such as carbon fiber are laid down onto the mold dry. A bagging film is applied over the mold with careful attention to air leaks as the process will not work properly without a perfect seal. A vacuum pump applies atmospheric pressure to the bag pushing the laminates against the mold. Resin is then infused into the mold cavity.
The benefits of vacuum infusion for carbon fiber parts are:
· Vacuum Infusion helps carbon fabric, which tend to be less pliable than fiberglass fabric, conform and press tightly against molds with complex tight and sharp curvatures and hard-to-reach areas resulting in a high-end “pressed-to-the-surface” look very similar to parts made using a pre-preg carbon process. This helps give the carbon a very nice uniform and flat surface effect, which is what is ultimately desired for a visually appealing carbon part. There are very minimal to no voids on a properly vacuum infused part.
· Vacuum Infusion produces stronger and lighter parts by minimizing resin-to-glass ratio compared to the same parts built using a conventional wet lay-up process. Mechanical property is within 70-80% of pre-preg carbon, which is outstanding considering the significantly lower cost of production.
Vacuum infusion is not easy to execute on non-flat parts. Molds require large flanges and need to be air leak free. The bagging technique is also complicated and tedious and needs to be air leak free as well. A part cannot properly infuse without achieving a perfect air tight seal, meaning zero air leaks. Being able to do this once does not guarantee success the next time around. It is a challenge every time the process is attempted.
BEWARE of companies claiming to offer vacuum infused parts only to supply you with parts made using a conventional wet lay-up technique. Some have gone as far to stage vacuum bag setups trying to “show” they vacuum infused a particular part. If there is no footage or pictures of resin successfully flowing through the laminate and covering the entire area, one should be skeptical. Vacuum infused carbon products command a higher premium than wet lay-up carbon parts, so it important to recognize key features and differences.
· If the carbon weave does not show signs of being pressed against the mold surface, it was most likely not infused.
· If the carbon fabric does not conform along sharp, tight, and complex curvature, it was either bagged improperly or was not infused. It is difficult to achieve this level of uniformity using a hand wet lay-up technique.
· If the part has an unusual amount of voids, it was most likely not vacuum infused as a properly vacuum infused carbon product has minimal to no voids.
· The carbon part should feel noticeably light and strong for its weight.
· The carbon part should have a tight and uniform high-end look comparable to parts made using a pre-preg carbon process.
We will provide a list (here) of products we offer currently made using a Vacuum Infusion process:
Mazda FD3S RX-7:
Spec-M (Mazdaspeed Style) 99 Spec Front Lip
Toyota JZA80 MKIV Supra:
Tom’s Style Spec-TMS Rear Diffuser
Lotus Exige Type 1 Sideskirts/Sidesteps