= ASTM International defines Additive Manufacturing as the “process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies. (ASTM F2792-10, June 2010)
"Traditional manufacturing has fueled the industrial revolution that has enabled our world today, yet it contains inherent limitations that point to the need for new approaches.
Manufacturing comes from the French word for “made by hand.” This etymological origin is no longer appropriate to describe the state of today’s modern manufacturing technologies, however. Casting, forming, molding, and machining are complex processes that involve tooling, machinery, computers, and robots. Similar to a child cutting a folded piece of paper to create a snowflake, these technologies are “subtractive” techniques, in which objects are created through the subtraction of material from a workpiece. Final products are limited by the capabilities of the tools used in the manufacturing processes.
By contrast, AM is a group of emerging technologies that create objects from the bottom-up by adding material one cross-sectional layer at a time.1 Revisiting the childhood analogy, this is conceptually similar to creating an object using building blocks or Legos.
The AM process begins with a 3D model of the object, usually created by computer-aided design (CAD) software or a scan of an existing artifact. Specialized software slices this model into cross-sectional layers, creating a computer file that is sent to the AM machine. The AM machine then creates the object by forming each layer via the selective placement (or forming) of material. Think of an inkjet printer that goes back over and over the page, adding layers of material on top of each other until the original works are 3D objects.
There are several AM processes that are differentiated by the manner in which they create each layer. One technique known as “Fused Filament Fabrication” involves extruding thermoplastic or wax material through heated nozzles to create a part’s cross sections.2 Filament feedstock is guided by a roller into a liquefier that is heated to a temperature above the filament’s melting point. The material is then able to flow freely through the nozzle. When the material reaches the substrate, it cools and hardens. Once the layer is complete, the build platform is lowered one layer-thickness by the Z-stage and deposition of the next layer begins. A secondary sacrificial material may also be deposited (and later removed) in order to support the construction of overhanging geometries.
Other AM technologies use different techniques for creating each layer. These range from jetting a binder into a polymeric powder (3D Printing), using a UV (ultraviolet) laser to harden a photosensitive polymer (Stereolithography), to using a laser to selectively melt metal or polymeric powder (Laser Sintering).Moreover, recent developments in the synthesis of end-use products allow for increasing numbers of materials to be used simultaneously. Think of an inkjet printer with six color cartridges printing simultaneously—but with different materials such as various metals, plastics, and ceramics in each cartridge." (http://www.acus.org/files/publication_pdfs/403/101711_ACUS_3DPrinting.PDF)
The Future of Additive Manufacturing
"Recent reports and developments suggest that AM development is gaining momentum and could be reaching a take-off point within the next decade. Hints of the future in a recent Economist, cover story, “Print me a Stradivarius,” captured imaginations throughout the policy world.5 A 2010 Ganter report6 identified 3D Printing as transformational technology in the Technology Trigger phase of the Hype Cycle7 (i.e., only 5-10 years from mass adoption).
While those involved in AM research might argue that it instead is emerging from a “Trough of Disillusionment” towards a “Slope of Enlightenment,” two recent significant advances have ignited broad interest in AM:
• Direct Metal AM: Significant improvements in the direct additive manufacture of metal components have been made in the past five years. Engineers are now able to fabricate fully-functional components from titanium and various steel alloys featuring material properties that are equivalent to their traditionally manufactured counterparts. As these technologies continue to improve, we will witness greater industrial adoption of AM for the creation of end use artifacts.
• Desktop-scale 3D Printers: As direct metal AM is breaking longstanding technology acceptance barrier related to materials, the recent emergence of desktop-scale 3D printers is eliminating cost barriers.8 Thanks to expiring intellectual property and the open-source (and crowd-source) nature of these projects, AM technology can now be purchased for around $1,000. Because of this low price point, interest in 3D Printing has skyrocketed as more and more hobbyists are able to interact with a technology that, in the past, was relegated to large design and manufacturing firms. This has democratized manufacturing, thus resembling the early stages of the Apple I’s impact on personal computing.
Thus, the 3D printing revolution is occurring at both the high end and the low end, and converging toward the middle.
One end of the technology spectrum involves expensive high-powered energy sources and complex scanning algorithms. The other end is focused on reducing the complexity and cost of a well-established AM process to bring the technology to the masses. Major advances will continue to be made in both directions in the next five years. “Direct metal” processes will continue to advance as process control and our understanding of fundamental metallurgy improves. These cutting-edge technologies will gain broader acceptance and use in industrial applications as the necessary design and manufacturing standards emerge. On the other hand, the quality and complexity of parts created by the desktop-machines will continue to improve while the cost declines. These systems will also see broader dissemination in the next 5 years—first through school classrooms and then into homes. While these two technical paths will continue to develop separately—with seemingly opposing end goals—we can expect to see a convergence, in the form of a small-scale direct metal 3D printer, in the next few decades." (http://www.acus.org/files/publication_pdfs/403/101711_ACUS_3DPrinting.PDF)
Report : Could 3D Printing Change the World? Technologies, Potential, and Implications of Additive Manufacturing. By Thomas Campbell, Christopher Williams, et al. Strategic foresight INITIATIVE. October 2011.