CAMX 2021 exhibit preview: Hawthorn Composites

Hawthorn Composites (Xenia, OH, U.S.), a division of Spintech Holdings Inc., is exhibiting a co-cured wing structure that was made using dry carbon fiber application, overbraiding, liquid infusion and Smart Tools. The company says this combination significantly lowers labor and material costs while maintaining structural integrity and weight neutrality, compared to conventional prepreg and autoclave-cured components.

The part was fabricated by pulling braided biaxial dry carbon fiber sleevings over each of the three Smart Tools to create the sheer webs and part of the structure of the control surface. Next, two layers of quasi-isotropic carbon fiber fabric are laid into the mold to form the lower skin of the control surface. The laid up Smart Tools are placed into the mold on top of the lower skin and one layer of the upper skin fabric is pulled over top of the tools. Multiple custom-formed noodles are then placed into the trailing edge of the control surface and sealed by the lower skin. Finally, the second layer of the upper skin is pulled over the first layer and secured in place.

The upper half of the clamshell mold is placed onto the lower half and secured with bolts. Vacuum bags are pulled through each Smart Tool and sealed to the intermediate seal plates. After the vacuum bags are secured, the pressure plates are attached to the mold, which allows the internal cavity of the mold to be pressurized to 75 psi of pressure and creates a reverse autoclave-like effect inside the mold.

The mold is then placed into an oven and plumbed for infusion using light resin transfer molding (LTRM). Next, the mold and resin are preheated and resin is infused to fully wet out the carbon fiber preform. Once complete, the exit and inlet tubes are closed, allowing the pressurized Smart Tools to create a hydrostatic force to consolidate the preform and voids during cure.

After the cure is complete, the mold is removed from the oven and the endplate is disassembled. The vacuum bags are removed from each cavity and the now elastic Smart Tool is extracted with low force from the cured composite part.