TECHNOLOGY AREA(S): Materials OBJECTIVE: Develop and demonstrate a high temperature polymer suitable for use as tooling for high-pressure injection molding operations. Polymer should be capable of being 3D printed via fused filament fabrication (FFF) processes utilizing a commercial-off-the-shelf (COTS) or minimally modified COTS 3D printer. DESCRIPTION: As the Army's primary depot for the repair and re-build of electronics and communications equipment, the Tobyhanna Army Depot (TYAD) regularly executes batch production of cables and cable harnesses which require the application of high-pressure injection molding to encapsulate the ends of these cables and harnesses with a protective polymer cover. These batches are small and conventional tooling cost and lead times drive up the overall cost of the production. Additive manufacturing provides the opportunity to rapidly develop and deploy manufacturing tooling without incurring the typical expense and lead times found using conventionally machined tooling. In addition, by employing additive manufacturing processes, designers and manufacturing experts are able to realize part complexities not previously possible. Current thermoplastic polymers used during 3D printing operations, especially those utilizing the Fused Filament Fabrication (FFF) process, have fairly low melting temperatures. This presents a problem when using these materials for injection molding tooling, especially during high-pressure injection molding processes where the mold temperatures can reach as high as 200 degrees Fahrenheit. As the technology development organization for the Army's Command, Control, Communication, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR) community, the US Army Communication-Electronics Research Development & Engineering Center (CERDEC) provides research, development and engineering support to TYAD. In this role, CERDEC is seeking to partner with a small business to demonstrate 3D printing of a high-temperature polymer on a minimally modified FFF desktop 3D printer. This demonstration must yield robust, 3D printed, high-pressure injection molding tooling which will be used in TYAD's production facilities to produce over-molded cable ends made with a two-part, chemically curing polyurethane compound meeting MIL-M-24041. An example of a compound meeting this requirement is PPG Aerospace's PR-1592 Potting and Molding Compound. High-pressure injection molding processes require constant tooling temperatures ranging from 180-210 degrees F. The tool experiences clamping pressures of 2000 psi and injection pressures range from 950-1100 psi. The tool will have to withstand these conditions and be capable of producing 200 parts without degradation. In addition, the Army is interested in exploiting the flexibility of desk-top style 3D printers which can accept a variety of non-proprietary materials. The Army recognizes current desk-top style printers are not designed for high temperature material extrusion and is interested in collaborating on a COTS-based system that is modified to handle these materials. Such a system must be capable of producing items ranging from 4 x 8 x 1 to 12 x 10 x 6 , at a minimum. PHASE I: Identify the key parameters associated with high-pressure injection molding at TYAD. Investigate current materials that meeting the temperature and physical characteristics required to satisfy these parameters. Conduct initial studies related to producing a high-temperature polymer material in a filament form suitable for 3D printing via FFF. Produce and demonstrate the material by delivering product samples along with a material characterization report complete with mechanical testing data. Conduct initial studies related to COTS or modified COTS equipment required to 3D print the high-temperature thermoplastic material. Determine if COTS equipment is sufficient to produce parts with this material. If not, justify the decision and provide a report to the Government citing key parameters required to be met by a modified machine. PHASE II: Demonstrate lab-scale production of the high temperature polymer in filament form. Acquire, and modify as required, a COTS FFF 3D printer and demonstrate print-ability of the material. Demonstrate ability to print representative high-pressure injection mold tooling samples. Demonstrate stability of these representative molds through actual cycling of a high-pressure injection molding process at TYAD. Design and produce a final tool to be delivered to CERDEC for direct comparison to the traditionally manufactured tooling at TYAD. Finalize and document any modifications to the 3D printer and deliver a TRL6/MRL6 prototype printer and 50 kg of high temperature polymer material, in filament form, to CERDEC for further testing and application. Fully document process parameters associated with producing polymer tooling for TYAD high-temperature injection molding applications. PHASE III: Advance material and 3D printing equipment to TRL 7/8 and MRL 8. Establish and demonstrate pilot line for production of the materials and the 3D printer. Fully document processes associated with producing the material and modifying and/or producing the 3D printer. Update the previously delivered prototype printer to meet the final configuration. Investigate commercial uses of this material and printer related to tooling and 3D printed end-items. Examples may include additional injection molding applications, tooling for composite material lay-ups, or polymer end-items that require high temperature stability. REFERENCES: 1: AFRL Report AFRL-RX-WP-TR-2017-0258, Extrusion Of High Temperature Polymer Resins To Enable Additive Manufacturing Of Functional Composites.2: MIL-M-240413: Chuang, Kathy, et al. Reactive Extrusion of High Temperature Resins for Additive Manufacturing . 2012, pp. 1 17, Reactive Extrusion of High Temperature Resins for Additive, https://nari.arc.nasa.gov/chuang4: https://www.researchgate.net/profile/Ahmed_Arabi_Hassen/publication/324442073_ADDITIVE_MANUFACTURING_OF_COMPOSITE_TOOLING_USING_HIGH_TEMPERATURE_THERMOPLASTIC_MATERIALS/links/5acdfa790f7e9b18965745f7/ADDITIVE-MANUFACTURING-OF-COMPOSITE-TOOLING-USING-HIGH-TEMPERATURE-THERMOPLASTIC-MATERIALS.pdfKEYWORDS: Additive Manufacturing, 3D Printing, High Temperature, Polymer, Injection Molding, Tooling, Production, Manufacturing, Manufacturing Technology, Manufacturing Systems, Manufacturing Capacity, Manufacturing Productivity, Manufacturing Equipment, Manufacturing Materials CONTACT(S): Andrew Davis (443) 395-5388 andrew.m.davis1.civ@mail.mil
