US Egypt Cooperative Research: Freeform Fabrication of Porous Metallic Structures

该奖项由 2009 年美国复苏和再投资法案（公法 111-5）资助。该合作研究项目由德克萨斯大学奥斯汀分校的 David L. Bourell 博士和埃及中央冶金研发研究所的 Khalid M. Elghany 博士承担，旨在评估和优化多孔金属结构的自由成型制造工艺。多孔金属结构具有多种重要应用，例如快速制造的人体定制植入物和特殊形状的植入物直接从电子设计 (CAD) 数据中过滤。本研究选择的自由曲面制造技术是选择性激光烧结/熔化 (SLS)。制造工艺（直接和间接）的优化将基于最终零件的相对密度以及与用于创建零件的 CAD 实体模型相比的尺寸精度。间接加工涉及使用瞬态粘合剂和后处理，而直接加工涉及在自由成型制造机中构建最终零件。将根据预期的服务应用来表征测试样本的机械行为。将进行详细的成本分析，以比较间接和直接 SLS 在零件生产中的效用。最后，将通过评估整个生命周期环境影响来解决每个流程的可持续性问题。 智力优点：在快速制造领域，关于直接与间接自由成型制造的整体效用存在持续的争论。该项目是这些选择性激光烧结 (SLS) 铁合金方法的首次“正面交锋”竞赛。鉴于直接 SLS 加工集中在欧洲和中东，而间接 SLS 加工则集中在美国，因此国际合作是可取的。更广泛的影响：从技术上讲，SLS 的商业化仅限于金属的间接加工，因为商用机器不具备直接熔化粉末的能力。有几家外国实体正在开发具有直接熔化金属粉末能力的商用机器。这些努力集中在德国、比利时和英国，但这种重点在埃及也很明显。在美国，商用聚合物机器适用于通过间接 SLS 进行金属加工。这里描述的工作将产生直接的商业影响，因为它为考虑快速制造的商业重要金属的直接和间接方法提供了明确的成本和环境影响比较。一名研究生将从代表性不足的群体中招募，参与美国的研究。 PI 每年组织的国际固体自由形状制造研讨会将成为展示和出版的国际场所。

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.