Metal Additive Manufacturing: A Review

Journal of Materials Engineering and Performance, Jun 2014

This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential.

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Metal Additive Manufacturing: A Review

William E. Frazier 0 0 William E. Frazier, Naval Air Systems Command, Patuxent River, MD . Contact This paper reviews the state-of-the-art of an important, rapidly emerging, manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free form fabrication, or 3D printing, etc. A broad contextual overview of metallic AM is provided. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts-on-demand while offering the potential to reduce cost, energy consumption, and carbon footprint. This paper explores the material science, processes, and business consideration associated with achieving these performance gains. It is concluded that a paradigm shift is required in order to fully exploit AM potential. 1. Introduction ASTM has defined additive manufacturing (AM) as a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies. Synonyms: additive fabrication, additive processes, additive techniques, additive layer manufacturing, layer manufacturing, and freeform fabrication (Ref 1). This definition is broadly applicable to all classes of materials including metals, ceramics, polymers, composites, and biological systems. While AM has been around as a means of processing materials for, arguably, over two decades, it has only recently begun to emerge as an important commercial manufacturing technology. In 2009, Bourell et al. (Ref 2) published a roadmap for AM based on a workshop of 65 key people in AM. Their report explored important facets of the AM including: Design Process modeling and control Materials, processes, and machines Biomedical applications Energy and sustainability applications In 2010, Frazier (Ref 3) published the results of a Navy workshop entitled direct digital manufacturing (DDM) of metallic components: affordable, durable, and structurally efficient aircraft. A vision of parts on demand when and where they are needed was articulated. Achieving the vision state would enhance operational readiness, reduce energy consumption, and reduce the total ownership cost of naval aircraft through the use of AM. Specific technical challenges were identified to address the quantitative objectives in the areas of (i) innovative structural design, (ii) qualification and certification, (iii) maintenance and repair, and (iv) DDM science and technology. Top level findings include High priority should be given to developing integrated in-process, sensing, monitoring, and controls. Machineto-machine variability must be understood and controlled. Alternatives to conventional qualification methods must be found; these are likely based upon validated models, probabilistic methods, and part similarities. Part-by-part certification is costly, time consuming, and antithetical to achieving the Navy s vision of producing and using AM parts on demand. Priority should be given to the development of integrated structural and materials design tools. This is needed to accelerate the adoption of AM by the aircraft design community and to promote new innovative structural designs needed to save energy and weight. Underline science of DDM needs to be developed. Physics-based models are needed relating microstructure, properties, and performance. New alloys must be developed to optimize properties. An understanding of how to control fatigue properties and reduce surface roughness, must be developed. Hederick (Ref 4) published a review of AM of metals in 2011. Presented is a nice summary of the various AM technologies and the dominate AM equipment manufacturers. AM equipment was broadly divided into powder bed systems, laser powder injection systems, and free form fabrication (FFF) systems. Some of the major findings of the report include: Materials processed using AM experience complex thermal processing cycles. There is a need to better understand the link between microstructure, processing, and properties for AM fabricated parts, as well as developing an AM materials database. He reports that there has been a lot of work on Ti-6Al-4V, but not so much on other alloys. There is a need reduce the variance in properties and quality from machine-to-machine across materials and machine types. Therefore, closed-loop feedback control and sensing systems with intelligent feed forward capability needs to be developed. Further, the ruggedization of AM equipment is needed. AM can be applied to the manufacturing of parts that cannot be made with standard machining practices. This possibility enables novel design methodologies. NIST held a workshop in December of 2012 and recently published the results Measurement Science Roadmap for Metal-Based Additive Manufacturing (Ref 5). Important technology challenges were identified in the areas (i) AM materials, (ii) AM process and equipment, (iii) (...truncated)


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William E. Frazier. Metal Additive Manufacturing: A Review, Journal of Materials Engineering and Performance, 2014, pp. 1917-1928, Volume 23, Issue 6, DOI: 10.1007/s11665-014-0958-z