SAMPE Journal - July/August 2011 - 42

Figure 10. Digitally coordinated tool family. Background Advanced Composite Structures needed a method to fabricate a capsule component for a remotely piloted vehicle. The capsule needed to provide mounting interfaces for internally mounted electronic components and a hardened exterior structure that was capable of withstanding the anticipated crash loads. The project needed design flexibility and fast turnaround times to integrate the rapidly evolving project requirements. FDM was selected to fabricate a consumable core and the necessary tooling to complete the capsule. Tool Design Consumable Core: The core provided mounting interfaces for the electronic components located inside the capsule. In addition, the core also provided an offset surface of the capsule’s aerodynamic surface that would be carbon-fiber laminated for crash strength. The core was built with FDM material ABSM30 based on the desired mechanical properties of the internal interfaces. Because ABSM30 has a relatively low heat deflection temperature, a laminating resin with a cure temperature of 70°C (160°F) was selected. Figure 10 shows the CAD design of the coordinated tool family and the resulting FDM parts after fabrication. Core Co-bond Tool: The co-bond tool was designed to provide a tooled surface that would stabilize the core and maintain the proper outside shape during the carbon lamination process. The tool was fabricated from polycarbonate for strength, stiffness, and good margin for the heat deflection temperature, see Figure 11. Cover Lay-up Tool: The capsule’s carbon-laminate cover was fabricated on a male lay-up tool that was designed to close out the top surface of the open capsule. The tool was fabricated from polycarbonate similar to the co-bond tool, see Figure 12. To optimize fabrication cycle time the lay-up tool was designed to build three covers in a single cure cycle. Witness pins built into the surface of the lay-up tool were used to coordinate the proper positioning of the coordinated trim and drill tools. Once laminated sheets were removed from the lay-up tool, witness marks could be drilled to enable pinning the trim and drill tools in the proper locations. Cover Trim Tool: This tool was used to pin into locators and scribe the edge of part on the carbon laminated sheet. Cover Drill Tool: This tool was used to pin into locators and accurately drill the proper mating hole pattern into the capsule covers. Tools were fitted with drill bushings to provide reusable drill tool. Processing Conditions The laminating resin for this project was selected based on the ABSM30 consumable core having a heat deflection temperature of 80°C (180°F) at 264 psi per ASTM D648 test methods. Hysol 9309-3NA resin was used with a 70°C (160°F) over cure under a full vacuum. Laminated parts resulted in very good bonding and high peel strength. Design Value Speed of implementation and proper fit up of parts provided velocity for this project. The FDM system was flexible enough to accommodate the range of parts and tooling required to complete the assembly. Enabled by a good selection of FDM materials, designers were able to optimize

Figure 11. Core co-bond tool 20cm x 13cm x 5cm (8in x 5in x 2in).
42 SAMPE Journal, Volume 47, No. 4, July/August 2011

SAMPE Journal - July/August 2011

Table of Contents for the Digital Edition of SAMPE Journal - July/August 2011