Removable Smart Tooling for High Temperature Composite Fabrication

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Advanced Materials;Sustainment OBJECTIVE: Develop removable tooling to produce complex contours by Automated Tape Placement (ATP) and Automated Fiber Placement (AFP) for thermoplastic composite parts. DESCRIPTION: Recent developments in ATP and AFP have revolutionized the composites industry. They have enabled affordable automated production with high dimensional tolerances. ATP/AFP operations often use a tool over which the material is laid. A removable tool allows for manufacture of complex parts in one operation rather having to make multiple parts and joining them secondarily. Such tooling remains a challenge as it needs to maintain its dimension and strength throughout the layup and consolidation process. Two promising technologies that can be leveraged in this STTR topic are washout tools and the melt tools. In the first washout material is manually poured into tooling and allowed to harden. Once the part is laid up on the tool and consolidated, usually water is used to washout the tool. There are now washout material available that can operate at up to 370 C which is sufficient for thermoplastics. However, additional work is needed to improve dimensional tolerances and develop it to a point that it can be used as an ATP/AFP tool. The second candidate technology is the meltout tooling. In this process the tool is molded using Resin Transfer Molding (RTM). Once the part is consolidated it is removed by heating. The challenge for this technology is that it currently uses materials that cannot be used at temperatures needed for thermoplastic manufacturing. Thus material discovery and/or development is needed to meet the topic objective. The program should produce the tooling such that it is highly repeatable (tolerances of +0.005 on thickness and +0.010 on everything else), is low cost considering both materials and forming process ($40-$50/part of size 1.5 x 12 x 0.5 ), does not require an oven post cure, has thermal shock and impact resistance equal to ceramics, and requires minimal processing time. The material should be capable of being used in autoclave processing with typical processing conditions of 350 F temperature and 100 psi pressure. In addition, the material used for the tooling should be environmentally friendly and should not create a hazardous waste stream. The washout tooling must also provide the appropriate characteristics required for the production of high performance composite structures. In addition to the above mentioned tolerances, it is important that the tooling produces the finished part with the appropriate dimensions. This requires that the washout tooling have the appropriate Coefficient of Thermal Expansion (CTE) such that a finished part meet the tolerances required for the processed component. It should be noted that carbon/Polyetherketoneketone (PEKK) tape will be one of the materials that the washout tooling will be required to be compatible with. PHASE I: Develop and demonstrate material and handling properties to produce proof of concept specimens with properties suitable for use in removable smart tooling applications, as detailed above. Demonstrate that the tooling material can be easily removed after a component has been processed at 700 F. Finally, demonstrate that the tooling material can be stored under ambient conditions. PHASE II: Develop and demonstrate a repeatable process whereby the awardee can produce a soluble rectangular mandrel with dimensions of approximately 1.5 x 12 x 0.5 with tolerances of +0.005 on thickness and +0.010 on everything else. These parts must also demonstrate that they are capable of handling the processing conditions typical of tape placement. In addition, they need to demonstrate that the process is scalable to 2 x 20 x 0.5 . Demonstrate the ability to develop and demonstrate the process for manufacturing the removable tooling with more complex shapes, as determined by the topic sponsor. The shape can include rectangular sections that are out of plane, or circular sections with jogs and protrusions, or foil shapes with complex curvature. Scale up the processing to be able to produce mandrels with planar dimensions of a minimum 12 x 24 . Demonstrate that the manufactured component meets the dimensional tolerances established by the Technical Point of Contact (TPOC). PHASE III DUAL USE APPLICATIONS: Perform a functional demonstration to DoD stakeholders arranged by the Navy team. Help transition the technology to a DoD original equipment manufacturer. While focused on thermoplastic the tooling will also be useful for thermoset AFP and ATP. The commercial aircraft industry would benefit significantly from low cost tooling material that allows for the fabrication of reproducible low cost composite parts by reducing the part count for complex shaped components. The tooling can also be used in naval platforms (ships, subs) which could benefit from reduced part count and complex composite components. REFERENCES: 1. Black, Sara. New options for trapped tooling. CompositesWorld, July 1, 2011. http://www.compositesworld.com/articles/new-options-for-trapped-tooling 2. Oromiehie, Ebrahim; Gain, Asit Gain and Prusty, B. Gangadhara. "Processing parameter optimisation for automated fibre placement (AFP) manufactured thermoplastic composites. Composite Structures, Volume 272, 15 September 2021, 114223. ISSN 0263-8223. https://doi.org/10.1016/j.compstruct.2021.114223 KEYWORDS: Removable tooling; Washable tooling; melt tooling; composites manufacturing; thermoplastic composite; low cost manufacturing; complex shapes