H. Watts and W. Huberty
Mississippi State University Advanced Composites Institute,
United States
Keywords: thermoset, reactive additive manufacturing, RAM, cure
Summary:
Mississippi State University's Advanced Composites Institute (ACI) is an expert in composite design, engineering, fabrication, and testing, continually surpassing perceived boundaries. The ACI resides in a 50,000 sq. ft. facility, with large-scale capabilities: 50 ft oven, 40 ft. stitching robot, etc. Recently, in partnership with Magnum Venus Products, the ACI has procured a unique and innovative large-scale (8’x4’x4’) thermoset (TS) Reactive Additive Manufacturing (RAM) 3D printer. The MVP system can also be extended in 4x4’ sections for larger scale prints. Rather than fusing layers of molten thermoplastic with a heated nozzle as in conventional fused deposition model 3D printing, RAM utilizes a two-part reactive material system that is mixed online and deposited on a print bed at ambient temperature. The reactive mixture, typically epoxy or vinyl ester resin, can either self-cure at room temperature or, for higher performance, can be post-cured in an oven. There are significant electrical savings for RAM due to the elimination of heating: >99.8% and >80% savings in electricity for large-scale FDM and pellet-extrusion FDM, respectively. With materials available that support the production of final use tooling for applications requiring dimensional stability at elevated temperatures and pressures, such as found in an autoclave or closed molding processes, this technology addresses one of the main obstacles preventing the use of thermoplastic additive manufacturing for high-rate production of tooling for the composites industry. The novelty of this technology also opens the door for research and development of new material systems to enable the production of molds with specific material characteristics. Our raw material supplier has several different material choices, with several that approach or beat the dimensional stability of aluminum. The open-layer time can be up to 10 days (distinct to RAM), allowing for various inserts, such as foams, sensors, internal support, or multi-materials, to be inserted directly during printing. MVP was also nominated for a 2021 CAMX award for producing a 90° overhang without any external support. With this in mind, the ACI has partnered with raw material suppliers to test, develop and optimize RAM materials and associated lightweight composite products. RAM will enable the ACI research team to produce low-cost, high-rate, environmentally friendly composite tooling in support of our goal of developing comprehensive design, production, scaling, validation, and technology transfer of innovative, low-cost, high-rate prototype tooling for advanced composites manufacturing in Mississippi.