Additive manufacturing (AM) has skyrocketed in visibility commercially and in the public sector. This article describes the development of this field from early layered manufacturing approaches of photosculpture, topography, and material deposition. Certain precursors to modern AM processes are also briefly described. The growth of the field over the last 30 years is presented. Included is the standard delineation of AM technologies into seven broad categories. The economics of AM part generation is considered, and the impacts of the economics on application sectors are described. On the basis of current trends, the future outlook will include a convergence of AM fabricators, mass-produced AM fabricators, enabling of topology optimization designs, and specialization in the AM legal arena. Long-term developments with huge impact are organ printing and volume-based printing.

Metallic materials for 3D printing - Volume 41 Issue 10 - Suman Das, David L. Bourell, S.S. Babu

Silicon infiltrated silicon carbide parts have been manufactured using selective laser sintering (SLS). The processing route has been defined, including post-processing steps: formation of a green part from silicon carbide powder using a phenolic binder, infiltration with a transient epoxy binder, dissociation of the binders thermally to create a brown part, heating the brown part to the infiltration temperature and infiltrating with molten silicon. Following a review of infiltration in freeform fabrication with emphasis on SLS, a dimensional analysis study was performed. Cubes 25.4 mm on each side were selective laser sintered and measured after each processing step. The largest dilatation (volume strain), 7.3%, was associated with creation of the green part relative to the computer solid model. The smallest dilatation, −6%, was associated with binder dissociation shrinkage. These volume strains nominally offset, resulting in creation of non-metallic parts with small dimensional errors relative to the computer solid model.

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 into rapid 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.