3D Printing: Speaking the Language
Todd Grimm posted on February 02, 2012 |

What’s the difference between 3D printing, additive manufacturing and rapid prototyping?

by Todd Grimm, Editor

  • 3D printing is the popular term when describing process that make objects additively.
  • 3D printing and additive manufacturing are interchangeable terms.

Over the 25 years that the technology has been available, nothing has been more hotly contested than what moniker to use. There have been many attempts to coin the perfect name, but few have endured.

The debate is now over. Through popular opinion and heavy media support, 3D printing is the clear winner. Yet, it will take some time for all to abandon the other names.

Now to the question posed, is there a difference between 3D printing and other common names? For additive manufacturing, there is no difference. Aside from some subtle nuances, these are synonyms. 3D printing and additive manufacturing are interchangeable terms for all additive processes, independent of application.

There is a big difference, however, between 3D printing and rapid prototyping. And the difference is cause for celebration. 3D printing is a process, in the same vein as machining, molding and casting. Rapid prototyping is just one of many applications that fall below the 3D printing umbrella.

Stereolithography SLA1

SLA1 (circa 1989) was the original rapid prototyping machine.

History Lesson

So, why the hotly contested debate, and why so long to agree on one name?

Recall that at its inception the technology operated under the rapid prototyping banner. This worked well in the early days; it distinguished both its key advantage and primary application. But as time passed, it proved too limiting and too attractive to other prototyping approaches.

In the mid-1990s, industry coined rapid tooling and rapid manufacturing to indicate that the technology had progressed beyond prototype applications. This proved too alluring to companies with established processes that also did prototyping, tooling and manufacturing quickly. So, if a company could machine parts and tools in short order, it borrowed the names.

  • 3D printing or additive manufacturing: Process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies.
  • Non-geek speak: 3D printing — "growing” physical models direct from 3D digital descriptions.

This muddied the waters. It became impossible to distinguish additive processes from all others. To counter this, industry players began coining alternatives. In the 1990s, terms like fabber, freeform fabrication (FFF), solid freeform fabrication (SFF), desktop manufacturing and solid imaging arose. None of these ever took hold.

In the late 1990s and early 2000s, manufacturing production parts was the big area of interest. The commonly heard rallying call was “for every prototype, there are millions of production parts.” Who wouldn’t want a piece of that action?

EOS DMLS - EOSint M 280

EOSINT M 280 is a production metal sintering machineEOS GmbH

To distinguish additive from other manufacturing processes and promote the application, many new terms emerged. Among them: layer manufacturing (LM), additive layer manufacturing (ALM), direct manufacturing (DM), direct digital manufacturing (DDM) and additive digital manufacturing (ADM). Many of these are still used today, but overall, the popularity is waning.

One alternative caught on and almost stood the test of time — additive fabrication (AF). Trade publications enthusiastically adopted it, and vendors followed their lead. But, additive fabrication wasn’t catchy and was a bit misleading — fabrication is one discipline in the manufacturing world.

ZPrinter 150

ZPrinter 150 has a lineage that includes the first systems to print with inkjet technology. 3D Systems Corp./Z Corp.


That brings us to the present.

Two years ago, a standards body within ASTM International (www.astm.org) officially adopted (and defined) additive manufacturing (AM) as the preferred term. Note that in this context, manufacturing isn’t an application. It is a process (think “manufacturing with additive technologies”).

At the same time, ASTM defined 3D printing as a specific class of additive manufacturing systems — either those that used a printing-like process (e.g., an inkjet head) or the low-cost, desktop systems. But it left the door open by allowing a third definition; the one we are using today.

Backed by this standards organization and adopted by professionals in the industry, additive manufacturing continues to be a supported and oft-used term.

Power of the People

Like the terms that came before it, popular opinion has countered ASTM’s efforts to standardize on additive manufacturing. 3D printing has become, by far, the most common name.

Why? 3D printing distinguishes the process from all others; the Average Joe gets it; it plays into the current atmosphere of 3D movies, TVs and apps; and it retains a futuristic flavor.

So, 3D printing is the overarching term for all additive processes, technologies, system classes and applications.

3D Printing hieracrchy

The 3D printing hierarchy spans all industries, technologies, applications and demographics.

Unlike rapid prototyping, it succeeds in distinguishing the process from all others because it fundamentally implies an additive, layer-by-layer approach to create physical objects. And it works because, like all other manufacturing approaches, it is a generic process. The name doesn’t specify an application or sub-type.

Like the established manufacturing terms, simply add a few words to clarify what you are talking about. For example:
  • Prototype machining » Prototype 3D printing
  • Machining: milling, turning, boring » 3D printing: extruding, jetting, sintering
  • Desktop machining » desktop 3D printing

Oh, the subtle nuance between 3D printing and additive manufacturing? 3D printing leans toward the processes for less demanding applications and favors the casual user. Additive manufacturing implies processes for more demanding applications and favors the professional, expert user.From this day forward, that is the context in which Engineering.com will use 3D printing and additive manufacturing.

Speaking of LanguageEngineering.com has opted to follow popular opinion and standardize on 3D printing as the term of choice. On occasion, you will see reference to “additive manufacturing” when distinguishing between demanding and less demanding applications and “rapid prototyping” when discussing prototyping applications.

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