L. Waganer 3-4 March 2008 ARIES Project Meeting at UCSD

1. Advanced Fabrication - Future Vision for Fusion? L. Waganer 3-4 March 2008 ARIES Project Meeting at UCSD

2. Advanced Prototyping Has Reached the Consumer Marketplace From Popular Science, December 2007 Issue Link to article http://www.popsci.com/popsci/flat/bown/2007/hometech/item_79.html THE DESKTOP FACTORY 125CI 3D PRINTERPRINT YOUR OWN PARTS The Jetsons-esque technology of fabricating three-dimensional objects is finally available for the home workshop, and at a fraction of the cost of industrial machines. Create your design on a PC, press “print,” and voilà: You’ve got a new coffee cup—or just about any hard plastic object that will fit inside the 5x5x5-inch chamber. The 90-pound, microwave-size machine swaps the typical expensive printing materials for affordable nylon-based powder, which is hardened by a halogen lamp instead of a pricey laser and deposited in 0.01-inch layers onto a platform to build the final object. The printed parts can be painted, but future versions could print in color. $5,000; desktopfactory.com

3. Time for Reflection I have been showing you over the past several years the progress of rapid prototyping, or additive machining, going from a laboratory novelty to a consumer novelty. Now we have to consider the potential that this technology has for application to fabricate fusion components more easily and cheaply. If we can dream it, we can build it?

4. What Are Others Doing? “ADDITIVE/SUBTRACTIVE MANUFACTURING RESEARCH AND DEVELOPMENT IN EUROPE”, Dec 2004 Report by World Technology Evaluation Center, Inc., 2809 Boston Street, Suite 441, Baltimore, Maryland 21224 http://www.wtec.org/additive/report/additive-report.pdf Sponsors: NSF, DARPA, ONR, NIST ABSTRACT This report is a review of additive/subtractive manufacturing techniques in Europe. Otherwise known as Solid Freeform Fabrication (SFF), this approach has resided largely in the prototyping realm, where the methods of producing complex freeform solid objects directly from a computer model without part-specific tooling or knowledge started. But these technologies are evolving steadily and are beginning now to encompass related systems of material addition, subtraction, assembly, and insertion of components made by other processes. Furthermore, these various additive/subtractive processes are starting to evolve intorapid manufacturing techniques for mass-customized products, away from narrowly defined rapid prototyping. Taking this idea far enough down the line, and several years hence, a radical restructuring of manufacturing as we know it could take place. Not only would the time to market be slashed, manufacturing itself would move from a resource base to a knowledge base and from mass production of single use products to mass customized, high value, life cycle products. At the time of the panel’s visit, the majority of SFF research and development in Europe was focused on advanced development of existing SFF technologies by improving processing performance, materials, modeling and simulation tools, and design tools to enable the transition from prototyping to manufacturing of end use parts. Specific examples include: laser sintering of powders, direct metal deposition and laser fusion of powders, and ink jet printing techniques. Truly integrated layer-by-layer additive/subtractive processes under development are limited; European emphasis was on creating an entire process chain to create new business models.

5. What Are Others Doing? WTEC Evaluation, Cont. In Germany, the Fraunhofer Institute for Laser Technology (ILT) has developed a selective laser melting technique for direct production of metallic parts. Commercialized by TRUMPF (www.trumpf.com) and announced at Euromold 2003, the process, shown in Figure 2.12, is essentially direct selective laser sintering of metallic powder without the use of intermediate binders. Metal systems researched include Ti-6Al-4V, H11 tool steel, 316L stainless steel, and cobalt-chromium alloys for dental restorations. Part resolution is about 100 microns with reported surface finish on the order of 30-50 microns. Applications include functional prototypes, short run parts and molds, medical implants, and tooling inserts EOS Finland has developed tool steel H20 for use in commercial EOSSINT M machines. Called direct metal laser sintering (DMLS), H20 parts such as those shown in Figure 2.13 are made with a layer thickness of 20 μm, dimensional accuracy of ±50 μm, and surface roughness after shot peening of 3-6 μm.

6. What Are Others Doing? WTEC Evaluation, Cont. Loughborough University researchers are working with additive manufacturing to create textiles. Textile Representation Actual Fabric Finished Product

7. What Are Others Doing? WTEC Evaluation, Cont. Figure 3.7. High speed sintering process: commercial reality of rapid manufacturing. (Loughborough University 2000)

8. What Are Others Doing? WTEC Evaluation, Cont. MATERIALS DEVELOPMENT – Powder Metals Figure 4.2. Gas-atomized (left) and water-atomized (right) 316L stainless steel powder. (Pinkerton and Li 2003). Note water-atomized is ¼ cost of gas-atomized. Figure 4.3. Laser-clad layers of 316L using gas-atomized particles (left) and water-atomized particles (right). The higher density structure (right) is attributed to reversal of Marangoni convection in the melt pool due to slightly different chemistry of the powder associated with the atomization method. The surface tension-driven convection is shown qualitatively in the inserts. (Courtesy Professor L. Li)

9. What Are Others Doing? WTEC Evaluation, Cont. MATERIALS DEVELOPMENT – Ceramics Notable advances in ceramics processing have been made in the past decade or so. An excellent and timely review of additive manufacturing of small scale devices using ceramic powders is Heule et al. (2003). “Top down” approaches such as direct writing methods, ink-jet printing, micro-extrusion, and lithography-based methods are discussed, along with more fundamental “bottom up” methods such as self-assembly for synthesis of micro- and nano-scale ceramic materials. Figure 4.6 shows a two-dimensional structure fabricated of ZrO2 by ink-jet printing with a 170 μm ± 10 μm resolution (Zhao et al. 2002). The inks, with a solid loading of 14 volume percent, possess unusual rheological properties, leading to new challenges in process design. This particular ink was dispensed using a Xaar XJ500 print head. Figure 4.6. Ink-jet printed, two-dimensional ZrO2 structure with 170 μm resolution. The distance between the outer vertical surfaces of adjacent walls is approximately 1 mm. (Zhao et al. 2002) Close to actual size

10. What Are Others Doing? WTEC Evaluation, Cont. Several long-term challenges exist in additive/subtractive manufacturing: • First is the need to improve part surface finish. Current practice involves hand finishing. The trend is towards non-tactile post-processing techniques, but perhaps new processes will be developed that address this critical technological aspect. • A second challenge is mesoscale and perhaps nanoscale object manufacturing. Examples are print heads and fiber-optic coupling devices, although success in this area would be expected to spill over into microelectromechanical systems and nanostructures. • A third area of challenge particularly suited to the powder technologies is creation of novel microstructures for advanced engineering applications. Examples include directionally solidified components, parts with compositional gradients, and non-equilibrium microstructure. • A final challenge is successful commercialization of a multiple materials machine. While some isolated success has been achieved in the research community, significant challenges remain in the area of material delivery and computational representation of compositionally graded structures.

11. What About Bigger Stuff? Sciaky, Inc, primarily know for welding systems, has been working with EBFFF (Electron Beam Free Form Fabrication) technology for many years and has performed programs using a wide range of materials, including titanium, nickel, stainless steel and refractory alloys. See example below. Fabricate OEM Structures and Equipment beyond prototype stage Machining Preforms   Save 80-90% of metal purchase of hogout.   Save 80% of overall delivery time.   Eliminate rough machining steps and one step over hogouts.   Go directly to final machining step. Less costly than forgings   Eliminates blocker die series and repeated heat treatments.   Eliminates shaper dies and heat treatments.   Cuts 90% of delivery time delays from making dies.   Eliminates 80-90% of rough machining over forging.   Go directly to final machining step. Less costly than castings   Saves making molds and skips molten metals issues.   Cuts 90% off delivery times. http://www.sciaky.com/62.html

12. What About Bigger Stuff? More info from Sciaky for EB Free Form Fabrication • Fabricate Hybrid Structures • Meets future requirements of "Tailored" structures not achievable by legacy forging, casting, or machining of monolithic materials. • Only additive method able to provide hybrid structures with lugs and bosses without high fault zones associated with castings. • Ability to vary alloy and chemistry throughout the landscape of a component to vary strength, fatigue performance, toughness etc. throughout a part's geometry. • Potential weight savings over monolithic structures. • Create unique part properties. The EBFFF fabrication sequence for a 24-inch wide gimbal. http://www.sciaky.com/62.html

13. Moving From Today’s Environment To Tomorrow’s Vision Fusion seriously needs low cost and reliable components and subsystems. Existing fusion facilities have been operating with experimental or existing components with low power and duty cycles. In the future, we need to develop more capable and more reliable subsystems with significantly lower costs.

14. Possible Advanced Fabrication of Subsystems and Components • Additive Fabrication • Integrated, low cost FWB, divertor, RF modules • Ferritic steel or SiC with integral tungsten surface and SiC insulation layers • Low cost shields, vacuum vessels, primary structure, coil structure, HX • Moderate cost S/C coil cables, high or low temperature • Tailored materials with new combinations or atom structures for low activation, high strength, low sputtering, enhanced heat transfer, directional conductivity • Nano structures for improved strength, heat transfer or insulation, etc. • Integral instrumentation and health monitoring capability • Morphing Structures • Divertors, RF launchers, maintenance equipment • Directly Formed Integrated Assemblies • Ability to form assemblies without physical part integation – subelements formed in-place

15. Recommendations There seems to be a need for an initiative to significantly lower the capital cost of the fusion power core while improving the performance and reliability parameters. Advanced Fabrication technology may be a possible means to achieve that elusive goal. With your support, I would suggest consideration of these ideas for inclusion in the Development and Fabrication of Low Cost, High Efficiency, and Long-Lived Power Core Components Issues within the Power Management section.