Preliminary Component Integration Utilizing Rapid Prototyping Techniques Ken Cooper, NASA Marshall Space Flight Center Pat Salvail, IITRI

Abstract employs an ultraviolet laser to selectively cure the epoxy into One of the most costly errors the shape desired. committed during the development of an 2. Selective Laser Sintering, a element to be used in the space industry powder-based process which is the lack of communication between uses a laser to melt cross design and manufacturing engineers. A sections of polymer or semi- very important tool that should be metallic powders into the utilized in the development stages by shape desired. both design and manufacturing 3. Laminated Object disciplines is rapid prototyping. Manufacturing, a solid-based Communication levels are intensified process which adheres layers with the injection of functional models of paper, plastic or composite that are generated from a drawing. and cuts each cross section with a laser. At the Marshall Space Flight 4. Fused Deposition Modeling, Center, this discipline is utilized on a another solid-based process more frequent basis as a manner by which extrudes a semi-molten which hardware may be tested for design thermoplastic through a and material compatibility. moving XY orifice to form the necessary shape. Background 5. Multi Jet Modeling builds solid wax patterns by printing layers Rapid prototyping in this text of hot wax directly through refers to a collective set of solid standard print jets. freeform fabrication technologies, which 6. Three Dimensional Printing build physical models directly from prints layers of binder into a computer aided design (CAD) data. The polymer powder matrix. fixtureless processes operate in an 7. Laser Engineered Net Shaping additive fashion, whereas each model is deposits a thin bead of metal built from the bottom upwards by adding powder into the focal point of a thin horizontal layers of material. high-powered laser, while the part is moved in the XY plane The MSFC maintains a unique underneath to form the cross rapid prototyping laboratory, equipped sections properly. extensively with each domestically available rapid prototyping technology; a These processes are employed at the total of seven processes in all. These MSFC for a variety of concurrent include the following: engineering tasks, including concept modeling, assembly verification, fit- 1. Stereolithography, a liquid- check analysis, flow functionality testing resin based technology which and investment casting pattern making. Applications at the MSFC the impeller blades the exact reverse of what the final part needed to be, and Shooting Star Experiment hence production was altered to make During the initial stages of the the final correct designs. Approximately Shooting Star Experiment, rapidly $300,000 again was saved by a simple produced absorbers were cast of a plastic model which cost about $1,000 to superalloy to be used in thermal prototype. experiments, prior to the procurement of the rhenium hardware. Additional savings in time and cost were then added throughout the life Early designs of the solar thermal of the Simplex program by the engine housing and absorber inserts application of rapid prototyping and were rapid prototyped in an investment investment casting to provide castability casting wax in a matter of days, and the verification of candidate materials, parts were investment shelled and cast fabrication planning and continuous on-site within four weeks. auditing with functional models and hardware. (Figure 3) These hardware castings have been, and continue to be, tested Space Shuttle Main Engine Fuel Ducts extensively by thermal elevation and During a redesign of the Space cycling in the MSFC Test Stand Area. Shuttle Main Engine, it was determined Data from these inexpensive models that replacement of existing supply and allowed for early analysis of the drain fuel lines would reduce weight and functionality of the engine design, as increase safety and reliability. well as saving the project just under $300,000 and six to twelve months of The previously used lines were lead time. (See Figures 1 and 2) fabricated by welding various shaped sections of steel line together in order to Simplex TurboPump access all of the required inlet/outlet Another application involved the ports of the engine. Simplex TurboPump, a high pressure experimental turbomachinery design. The new design called for The application of rapid prototyping continous feedlines to be custom-formed prevented a costly mistake in the from tubing to reduce the weight of the manufacturing of the pump’s complex welds, optimize flow and decrease the impeller. probability of fuel leakage. Five of the components were set to be machined, at an individual cost of Unfortunately, the first hot gas $60,000 each. The drawings had already duct to be fabricated didn’t integrate been delivered to the machine shop and properly after additional hardware was tooling-up had begun when a rapid attached to the engine during assembly. prototyped model was fabricated using The process to correct the problem was MSFC’s stereolithography apparatus. costly and time consuming, and it was determined that rapid prototyping The resulting plastic model patterns be fabricated for the remaining verified that the blueprints designated five ducts for fit verification. Each duct was approximately compatible and provide adequate seven feet in length and six inches in strength and density to prevent diameter, with a complex three- permeation or breakage. The funnels are dimensional curvature and precisely even chemically cleaned and reused placed junctions. The prototypes were several times prior to disposal.(Figure 5) fabricated in twelve-inch sections using the laminated object manufacturing Space Shuttle Main Engine Fuel Seals process at MSFC, and it took two to Another shuttle engine three weeks to fabricate the entire set. application of rapid prototyping occurred The engine contractor designed each recently when, after a design change, it section having dissimilar boss-and- was found that a particular fuel line socket alignments for proper assembly. didn’t match up properly with a pump.

These prototyped lines were The result was a need for a shipped to the engine contractor facility, flexible seal, which consisted of a 270- where they were assembled and mounted degree rotation of an eccentric nature. to an actual main engine to verify the The overall part required was about nine designs prior to manufacturing the inches in diameter. remainder of the required lines. A potential cost saving of approximately The contractor for the pump $35,000 per line was recognized by the received several solid prototypes of the application of the rapid prototyping flange from the MSFC rapid prototyping models, resulting in an overall potential lab. These parts were used to make savings of about $175,000 and several molds, which in turn produced the final months of lead-time. (Figures 4) products required to satisfy the needs of the engine. Meteorite Patch Kits One continuous application of Summary rapid prototyping at MSFC involves a project that applies meteorite patch kits. The application of rapid The process requires precise mixing of a prototyping technologies at the MSFC two-part solution to obtain the adhesive continues to yield significant cost and properties required for composite timesavings to NASA projects. material bonding. Increased use of these technologies is anticipated in order to cater to a A special funnel was designed concurrent engineering environment that which allows for accurate delivery of has been realized due to decreased each component of the adhesive mixture. funding allocations and project time Due to the low number of these funnels constraints mandated throughout the that are required, approximately two to agency. four every year, it is not cost effective to Similar applications and have them mass-produced. successes are seen throughout the private manufacturing industry, as well, where The solution is to directly profit margins and a highly competitive fabricate the funnels using rapid market drive companies to deliver prototyping. The materials used are products quickly and efficiently. Figure 1

Figure 2 Figure 3

Figure 4 Figure 5