Richard E. Crandall, PhD, CFPIM, CIRM, CSCP | January/February 2013 | 23 | 1
Exploring a highly significant new technology
Do the terms “additive manufacturing” or “three-dimensional (3D) printing” mean anything to you? If not, make a note of them now, because this new trend may represent a significant threat or opportunity in the near future. Many industry professionals see this innovation as a wave of manufacturing that will revolutionize the way many products are made.
Additive manufacturing gets its name because parts are produced by using a printer to add layer after layer of materials onto a surface to form a three-dimensional object. It’s like making a layer cake in the kitchen, except the additive manufacturing layers are much thinner (upwards of 2,000 layers per inch) and much more stable when finished.
In a comprehensive article on the subject, Berman (2012) explains that 3D printers seamlessly integrate with computer-aided design (CAD) software, which directs the printer operation to deposit layers of materials to form the desired object. While still in its early stages of development, 3D printing has many researchers and practitioners actively seeking ways to improve and extend the applications of this process.
“The definition [of additive manufacturing] includes all applications of the technology, including the making of models, patterns, and prototypes for form, fit, and function; mold, die, fixture, and assembly tooling; and custom and limited-edition products, replacement parts, and short-run and series production. Rapid prototyping is the most popular application of [additive manufacturing] technology, but it is only one of many (Wohlers 2010).
Gibson, Rosen, and Stucker (2009) report that most additive manufacturing processes involve the following eight steps:
- Build the CAD software model to describe the external geometry.
- Convert the CAD file to the stereo lithography (STL) file format (the de facto standard).
- Transfer the STL file to the 3D printing machine.
- Set up the machine’s material constraints, energy source, layer thickness, and timing.
- Build the part (usually an automated process requiring only superficial monitoring).
- Remove the part, assuring there are no moving parts or high temperatures.
- Perform post-processing (cleaning, support, and removal).
- Actual application is the final step, and it may require additional treatment such as painting or assembly with other parts.
There are several processes that deposit layer upon layer of material to form a finished part, not just additive manufacturing. “The main technologies that can, today, be classified as rapid manufacturing technologies (as opposed to rapid prototyping) are selective laser sintering (SLS), selective laser melting (SLM), and electron beam melting (EBM)” (Diegel 2010). Diegel goes on to explain that a layer of material is deposited and then fused to the specified surface with either a laser beam (SLS and SLM) or an electron beam (EBM). The unfused material acts as support for all the layers above and is removed once the part is complete.
The first use of additive manufacturing was to make prototypes, and it was known at that time as rapid model prototyping (RMP). Prototypes could be made with a CAD design that was loaded into a printer. This approach made it possible to produce complex shapes that would have taken much longer to design and produce through conventional methods, such as molding and machining.
Once 3D printing became more commonplace, pioneers began to use it to make small lots of production parts. Although it was slow relative to numeric-controlled machines, it required much less time in the design and setup stages. Consequently, additive manufacturing was viewed as more effective when making small quantities. In addition, it was capable of making complex designs that had been difficult, if not impossible, to produce with conventional methods. It was during this period of expanded application that the designation changed from rapid model prototyping to additive manufacturing, a contrast to subtractive manufacturing, where material is machined away in order to reach the desired part. Some applications of model building include bicycle chains, gear boxes, and even miniature sculptures.
Some of the benefits of additive manufacturing include the following:
- It can eliminate the need to make custom tooling, which reduces the time to develop new product models for evaluation (Hessman 2012).
- 3D printing has the capability to make complex parts that would be difficult, if not impossible, with conventional casting and machining techniques. “Almost, without exception, if a part can be modeled on a computer in 3D, it can be sliced and printed, layer by layer, on an [additive manufacturing] system” (Wohlers 2012).
- Finished products have lower weights. Additive manufacturing has found application in building unmanned aerial vehicles and aircraft parts where the build time is faster and the lighter weight reduces fuel consumption (Wohlers 2012).
- It is possible to reduce the number of processes necessary to prepare the materials for use because the materials are powders. This results in a leaner and greener supply chain (Hargreaves 2011).
- The process can use almost all of the powdered materials it starts with. This compares favorably with the subtractive processes that may machine away over half of the material they start with (Velocci 2012).
- Topology optimization, a technique that helps pinpoint where to locate the material in a part, can optimize the strength-to-weight ratio (Wohlers 2012).
- It enables greater predictability and product reliability. Whether the additive manufacturing process uses a laser or an electron beam, it is possible to model the time and temperature profile at any location of a component (Velocci 2012).
- It reduces component count because additive manufacturing does not have the geometric limitations imposed on molds and dies. Thus, what would require multiple parts in conventional processing can be built in one part design (Wohlers 2011).
Additive manufacturing is used to produce replacement parts for washing machines and food processors, as well as small gears (Berman 2012). It is also being applied more and more by the aircraft industry, where lighter weight is treasured. Boeing has 200 different additive manufactured part numbers on 10 production platforms, including both military and commercial jets (Wohlers 2012). Another use involves a joint project between Stratasys and Optomec to produce a “smart wing” for an unmanned aerial vehicle model with functional electronics (Close-Up Media 2012).
In the automotive industry, General Motors (GM) has been using additive manufacturing for the past 20 years. In a lab with 15 specialists and 18 machines, GM cranks out some 20,000 unique parts a year, including bumpers, grilles, spoilers, and mirrors. It also can build prototypes of engines, transmissions, brake lines, and drive shafts (Fish 2011).
Do-it-yourself enthusiasts also are looking at the possibility of using 3D printers to make craft items, jewelry, and other small parts. However, Whitman (2012) cautions that 3D printing won’t be for the average person. Still, manufacturers continue to drive down the cost of low-end printers, with some now available in the $1,000-to-$2,000 range (Seitz 2012).
The medical field uses additive manufacturing to make hearing aid molds, dental crowns, and prosthetic limbs (Berman 2012). Wohler (2012) reports that the process is particularly effective for creating hearing aids and dental copings because additive manufacturing enables the creation of items that are unique in size and shape. Although the industry is heavily regulated, implant manufacturers in the United States were approved by the US Food and Drug Administration to manufacture certain products using electron beam melting in 2010 (Wohlers 2011).
Additive manufacturing also is used for training students in STEM (science, technology, engineering, and math) practices. The National Science Foundation has funded two Advanced Technological Education centers to develop additive manufacturing competencies and curricula: MatEd, the National Resource Center for Materials Technician Education; and RapidTEch, the National Center for Rapid Technologies. The project is designed to accelerate skills development by “decreasing the time lag between global [additive manufacturing] standards development, their translation into core competencies, active integration into curriculum, and their delivery in the classroom” (Fridan 2011). If the United States is to meet its future challenges, it must train more students to pursue engineering and other STEM careers. Students who like the hands-on experience of making things will become excited about additive manufacturing education opportunities (Lacey 2010).
Behrokh Khoshnevis, a professor of industrial and systems engineering at the University of Southern California in Los Angeles, has spent 15 years working on the idea of using additive manufacturing techniques to construct buildings. He believes they could be built at lower cost and that the method could be used to assemble emergency housing in case of disasters (Thilmany 2010).
Models at the Stockholm Fashion Show wore shoes manufactured in polyamide by laser sintering (LS) methods (Wohlers 2011). And New Balance Shoes uses additive manufacturing to design new products rapidly and keep up with market changes.
In one of the more exotic potential applications, NASA is planning to bring a 3D printer to the Space Station by 2014 to make replacement parts and tools. With the help of Autodesk, the organization already printed a wrench in zero gravity conditions (King 2012). NASA also used additive manufacturing to build 70 parts for the Mars Rover using a production-grade Stratasys 3D printer with its patented Fused Deposition Modeling technology (Plastics Technology 2012).
Vladimir Mironov, one of the most optimistic researchers, envisioned rapid prototyping, smart polymers, and cell adhesion eventually resulting in what might be called “organ manufacturing”—in other words, making body parts. He speculates, “Once we learn how to produce isolated body parts, we could eventually be able to build a whole body” (Mironov 2003).
Because of the newness of the technology, researchers and users are working their way through the learning curve to determine the best combination of materials and processes to produce an increasing variety of products. Some of the most often-cited shortcomings of additive manufacturing are
- slow manufacture time compared to numerical control machines
- weak bonding between layers that can lead to delamination and breakage under stress (Berman 2012)
- a need for some conventional finishing operations because of the ridges formed by the layer depositions.
This technology has great potential to help manufacturers produce locally and respond quickly to changes in demand. 3D printing increases flexibility and enhances proximity to both the design side of business and the demand side because manufacturing can be done effectively and efficiently in smaller units (Magnus 2012).
Terry Wohlers estimates the market for 3D printers will grow from approximately $2 billion in 2012 to $6.5 billion by 2019 (Gupta 2012). In a Wall Street Journal
article, Michael Malone (2012) lists 3D printing as one of his six sources of the “next American boom.” Meanwhile, the Department of Defense and the Department of Commerce have awarded $30 million to a consortium of regional businesses, universities, and nonprofit organizations to establish the National Additive Manufacturing Innovation Institute in Youngstown, Ohio (Hessman 2012).
There is no doubt that the application of this technology is going to swell exponentially. It will be fascinating to see where it takes us.
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If you would like a free annotated list of references on this subject, contact the author at firstname.lastname@example.org.
Richard E. Crandall, PhD, CFPIM, CIRM, CSCP, is a professor at Appalachian State University in Boone, North Carolina. He may be contacted at email@example.com