How Additive Manufacturing Makes Addition Better (and Cheaper) Than Subtraction

by Jeff Yoders
- Oct 31 2013 - 3 min read
Bespoke Innovations

For decades, small machining/manufacturing shops have been limited to subtractive processes, taking raw metal materials and cutting or drilling sections away to create a part or product. It’s a process that creates leftover material that may not be reusable, can require design changes just for the manufacturing process, and involves costly hours of machining time.

Additive manufacturing is the direct opposite—the process of making a 3D solid object of virtually any shape from a digital model, usually a CAD file. By now everyone has heard of 3D printing, an additive process that is achieved by using successive layers of material laid down in different shapes until the final design is composed. Additive manufacturing and 3D printing are basically the same thing, which often causes confusion in the marketplace.

3D printing is often used to describe consumer technology, and additive manufacturing is usually used for commercial manufacturing. Together, 3D printing/additive manufacturing are described by the American Society for Testing and Materials (ASTM) as “a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing technologies, such as traditional manufacturing,” and they are expected to grow to a $3.1 billion industry by 2016.

additive manufacturing
A prosthetic Sport Fairing (covering) from Bespoke Innovations

The many different additive manufacturing technologies available today offer much better economies of scale and design possibilities than traditional subtractive manufacturing. Reverse engineering via 3D imaging can re-create existing parts or make them whole, medical/dental devices and implants are already being created additively, laser sintering (3D printing in metal) can create high-tolerance internal machine parts, material extrusion and material jetting are both used for visual verification models, and 3D printing with electronics embedded can create whole electronic devices much more efficiently than in the past.

GE’s aviation division, the world’s largest supplier of jet engines, now produces a fuel nozzle for a new aircraft engine by printing the part additively with lasers rather than casting and welding the metal. This has been a boon for small machining/manufacturing shops, and many new shops have been able to start up with much lower overhead thanks to additive manufacturing processes. For those of you out there in CNC and traditional manufacturing shops, there’s no reason to be concerned as existing shops have also adapted quickly to rapid prototyping using additive manufacturing. Many of the design-for-manufacturing techniques you’re already using can be made even better and more efficient using additive processes.

additive manufacturing
Formula 1 racing team Lotus F1’s Wind Tunnel model SLA Air-Box prototype. Courtesy of 3D Systems.

“There is enormous cost pressure everywhere in the industry right now,” says Paul Van Metre, president of Pro CNC Inc., Bellingham, Wash. “Right now, Boeing is trying to cut 15 percent out of every supplier part. Most manufacturers and job shops don’t even have a 15 percent margin built-in to begin with. There’s not 15 percent to cut out and still have any margins left. The only way to achieve price reduction is to make the part cost less to make, and designing it for manufacturing is how you make the part cost less.”

In addition to not throwing away subtracted materials, additive manufacturing allows designers to create their products from a full 3D model communicated directly to the 3D printer or other manufacturing tool. The maker movement has created low-cost, do-it-yourself 3D-printing tools that, while they might not have the documentation and support of a major manufacturer, can give designers and manufacturers who know how to use them a much less costly production machine than previously available. Costly hours of machining a part subtractively can be eliminated and made faster by adding rather than cutting away a material. Machining processes such as rolling and lathing can be eliminated entirely.

additive manufacturing
WE DO design studio’s prototype of Stockholmsarenan (Stockholm Arena). Courtesy of 3D Systems.

To learn more about this new philosophy of manufacturing, check out this presentation by ARC’s Scott Evans at this year’s ARC World Forum. And read about 5 Manufacturing Trends Shaping the Future of Small Businesses.

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