US Egypt Cooperative Research: Freeform Fabrication of Porous Metallic Structures

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This collaborative research project is being undertaken by Dr. David L. Bourell, University of Texas at Austin, and Dr. Khalid M. Elghany, Central Metallurgical R&D Institute, Egypt, to evaluate and optimize freeform fabrication processes for porous metallic structures.Porous metallic structures have several important applications such as rapidly fabricated human-body-tailored implants and specially shaped filters direct from electronic design (CAD) data. For this research, the freeform fabrication technology of choice is Selective Laser Sintering/Melting (SLS). Optimization of fabrication processes (direct and indirect) will be based on the resulting relative density of the final parts and the dimensional accuracy compared to the CAD solid model that is used to create the parts. Indirect processing involves the use of a transient binder and post-processing, whereas direct processing involves building of the final part in the freeform fabricator. Test specimens will be characterized for mechanical behavior in anticipation of service applications. A detailed cost analysis will be performed to compare the utility of indirect and direct SLS for part production. Finally, sustainability issues will be addressed for each process by assessing the total life cycle environmental impact.Intellectual Merit: There exists in the rapid manufacturing field an ongoing debate on the overall utility of direct versus indirect freeform fabrication. This project is the first "head-to-head" competition of these approaches for a ferrous alloy by Selective Laser Sintering (SLS). The international collaboration is desirable given that the concentration of direct SLS processing is in Europe and the Middle East, whereas indirect SLS processing is centered in the US. Broader Impacts: Technically, commercialization of SLS has been limited to indirect processing for metals since commercial machines do not have the capability to directly melt the powder. There are several foreign entities developing commercial machines with capabilities for melting metal powder directly. The efforts are centered in Germany, Belgium and the United Kingdom, but this focus is evident in Egypt as well. In the United States, commercial polymer machines are adapted to metal processing by indirect SLS. The work described here will have direct commercial impact as it provides an explicit cost and environmental-impact comparison of the direct and indirect approach for commercially important metals under consideration for rapid manufacturing. A graduate student will be involved in the USA research with recruitment from underrepresented groups. The International Solid Freeform Fabrication Symposium organized annually by the PI will be an international venue for presentation and publication.