Introduction Why Additive - Manufactured Composite Molds? Composite manufacturing requires molds to produce multiple accurate parts. Traditional metal molds for parts can take months to years of planning, machining and costs. The ability to prototype and produce parts using low - cost, quickly - manufactured additive manufactured molds potentially reduce lead time and lower upfront costs for composite parts significantly. Project Scope: • Test viability of 3D print materials in autoclave conditions • Determine best printing and mold preparation practices • Study possible post - processing techniques • Perform FEA analysis to study material deformation under autoclave conditions Molds and Composites Testing Material Choices PPSF - Durable material that is primarily used for tooling and has a high resistance to chemical resistance. ABS - Chosen for small lot size fabrication, due to poor tensile strength and low heat resistance; ABS is best be used for small slot size fabrication. Ultem 9085 - Thermoplastic with high strength high thermal and high chemical resistance. Ultem 9085 has been used for aerospace flight parts and composite mold tooling. Ultem 1010 - Similar to Ultem 9085, Ultem 1010 has an HDT of 420F and has been extensively tested as additive manufactured composite tooling by Stratasys™ Mold Development Multiple molds were designed for testing; flat “waffle” molds were used for general testing and determining best practices. Geometrically complex surfaces molds were designed to create high stress points so defects or failures can be observed. Printing Molds in this project were printed using the Fortus 900mc™. Both GrabCAD and Stratasys’s Insight™ program gave multiple infill and layer thickness options for each mold variations; the infill option “Hexagram” was selected for use most often due to its overall strength when compared to other infills. Environment Material Testing We placed ABS and Ultem 9085 under the standard prepreg cure processes in an oven under vacuum bag pressure. ABS failed, 9085 passed, and so we continued ABS testing with hand - layup only. Surface Finish Testing We tested various different surface finishes, using epoxy, sanding, waxing, enamel, and primer, to prevent the epoxy in the composite layup from seeping into the molds. Layup Testing We tested carbon fiber prepreg layup on the Ultem and PPSF molds, and basic carbon fiber layup on complex ABS molds. While some of the surface finish stuck to the composite, the overall result was useable. Physical Testing Flowchart Experimental Conclusions Material selection: ABS was sufficient for unheated processes, While Ultem 1010 , Ultem 9085, and PPSF all worked similarly well for heated processes (350F). PPSF molds did not have as much post - heat treatment adhesion to the part compared to Ultem molds, leading us to suspect PPSF would have less surface finish loss/deformation over time, but further testing is necessary to provide evidence for such a claim. Print Practices: The high - heat materials needed to be specifically oriented on the print tray so that they were in front of the heater, otherwise there would be severe warpage and other failures. The main concern with using 3D printed pieces as composite layup molds is the epoxy seeping through the layers in the mold. While the ABS molds were useable without any surface finish processing, the pieces printed upside - down, with the surface at the bottom, or with thicker surface walls, appeared to have less epoxy seepage and the composite was far more easily removable. Surface Finish Processes: While not completely necessary, using surface finish processes did appear useful. Sanding was not difficult on any mold material, and both the epoxy and enamel/primer improved the surface finish of the layers. However, the enamel/primer surface coatings did tend to stick to the carbon fiber after it cured, and so post - processing would be necessary. More surface finish processes may also work better for layup, and so future research is needed. ANSYS Conclusions Modeling performed in Ansys was used to acquire detailed deformation results for each material under autoclave conditions Ansys results show functionally identical deformation in Ultem 1010 and Ultem 9085 within specifications . PPSF had similar deformation values but showed different deformation patterns based on PPSF's Poisson's ratio. As such we consider PPSF a minutely less useful material when considering deformation Overall the analysis proves that the materials are suitable for composite fabrication within tolerances of 0.007” to 0.02. Isaiah Fleming, Andrew Jenke, Michael Malec, Kurt Romberg, Annalin Valero Main Literature Cited Ahmed Arabi Hassen, J. L. (2016). The Durability of Large - Scale Additive Manufacturing Composite Molds. Conference: CAMX – The Composites and Advanced Materials Expo, 10. Bastien Carel, G. H. (2018). DEMONSTRATION OF ADDITIVE MANUFACTURING (FDM) FOR PRODUCTION COMPOSITE TOOLING AT DASSAULT FALCON JET. SAMPE 18 - Long Beach, 15. Brian Post, L. L. (2016). ADDITIVE MANUFACTURING OF COMPOSITE TOOLING. Oak Ridge National Laboratory. Acknowledgments Thank you to Lockheed Martin and Brian Jessen for their generous assistance, and to Dr's Musimbi and Kalla, Dave McCallum, Robert Audretsch, Harley Leho, and Clayton Bryant. Additive - Manufactured Composite Molds ANSYS Analysis ANSYS's FEA capabilities were utilized to obtain theoretical results to compare with our experimental results, in addition to simulating environmental conditions we were not able to do ourselves INVAR 36 A simplified method of modeling a 3D printed part was used to approximated material properties without consuming large amounts of processing resources. ULTEM 1010 Parts were modeled in two parts, an outside shell acting as the solid print wall of the part, with an inner filling of lower density to approximate the properties of the sparser infill. ULTEM 9085 Parts were analyzed to determine thermal loads during the curing process and then coupled with an environmental pressure to fully simulate autoclave conditions: (350 F, with 100 psi.) PPSF Print Samples : Using Additive Manufacturing; print samples of four(4) materials: ABS, PPSF, Ultem 9085 and Ultem 1010 Oven/Heat Testing: Tested samples of each material at 311 F/ 155 C for two(2) hours to test autoclave viability Chemical Testing: Conducted testing for each printed sample with chemicals and resins commonly used in composite fabrication to determine any unforeseen chemical reactions Surface Finishing Testing: Investigated various surface finish techniques to determine best practices for mold preparation and determine mold porosity Composite Layup: Conducted hand - layups for ABS molds to simulate “wet” composite fabrication Conducted in - Autoclave simulated testing on PPSF/Ultem molds to simulate normal prepreg composite fabrication Durability Testing: Repeat multiple tests three(3)+ on previously molds to determine the effects of multiple uses on each mold Complex Testing: Using best practices concluded from previous testing; run durability testing for complex molds