3D printing / additive manufacturing / rapid prototyping — what’s the difference?

It’s not a new debate. For some, it’s not even a debate at all. What, though, differentiates the names by which we call the processes machines use to build objects by adding material?

This isn’t a definitive guide, but in reflecting on the ways in which we talk and write about 3D printing (no hyphens in that, please), I’ve turned to industry insiders, experts, observers, and analysts to open the discussion and compare notes. Much of this debate took place on my LinkedIn and Twitter feeds, as digital contact allows for a neutral meeting grounds for a meeting of the minds.

(TL;DR version at bottom, if you’d rather skip the historical discussion.)

Where did these terms come from?

These technologies trace their origins to the 1980s, when the first patents were filed; research can be traced back to the 1960s, but the technologies that eventually became stereolithography (SLA), fused deposition modeling (FDM), and selective laser sintering (SLS) emerged directly out of the work of the ‘80s. The earliest applications were focused squarely on prototyping.

Rapid prototyping (RP) refers to the speed with which prototyping could be done using these new technologies. As with any new technology, agreeing on what to call that took some time. This is especially so as, as Wikipedia notes, RP involves a suite of technologies, not just one thing.

The first nomenclature debates began here, as noted journalist and industry expert (and Fabbaloo contributor) Rachel Park observes:

“This debate is more than 2 decades old. In its first incarnation – it centred around RP versus RT (Rapid Tooling) versus RM (Rapid Manufacturing) and the various combinations of those acronyms – RP&T, RP&M RPT/M etc.”

Indeed, of the growth of this debate and the early terminology, Stamatis Polydoras, Laboratory Teaching Staff and Research Associate at the National Technical University of Athens, noted:

“Terminology has been a debate for almost two decades. Historically, technologies started officially described as Rapid Prototyping, since they mostly applied to the work of engineers involved in product development. Alternative terms back at that time, Layer Manufacturing, Free Form Fabrication, Generative Manufacturing and others. Specifically 3D Printing was patented by MIT as the particular RP technology making objects out of powder by jetting adhesive  (today Binder Jetting). Over the years 3D printing was more and more used by the general public instead of RP, as a more conceivable and generalized term, just like many people refer to a 4×4 car as a Jeep! Nowadays more or less everything is solved officially within standard ISO/ASTM 52900:2015 (formerly ASTM F2792). Generally though, Additive Manufacturing is the term, but people tend to consider 3D printers as the smaller / desktop / plastic -polymer-resin handling systems and AM equipment the more professional /industrial ones, especially the metal systems.”

“3D printing” (3DP) came about as a term circa 1993, as MIT developed an inkjet technology soon licensed to Z Corp.

The term was relatively quickly popularized; accessible and easy to understand, 3D printing referred to printing… in three dimensions.

That’s not all there is to it, of course, and while significant developments were based in inkjet printing, not all were. Especially as capabilities improved and the burgeoning industry began to pick up momentum with more industrial contributions and production focus grew, another term emerged to point to this new direction: additive manufacturing (AM).

As the technologies continued to develop, with more techniques being developed to build up objects, ASTM International defined seven unique categories that fall under the umbrella of additive manufacturing. In 2009, ASTM F42 on Additive Manufacturing Technologies was formed, creating an important authoritative source for standards. The committee’s overview refers to both 3D printing and additive manufacturing throughout its discussion:

“Additive manufacturing (AM), also known as 3D printing, uses computer-aided design to build objects layer by layer.”

This conversationally-interchangeable use of both ‘3D printing’ and ‘additive manufacturing’ is relatively pervasive today.

What does the industry have to say?

Industry participants offer a look at how and why they use each phrasing, through the public discussion still ongoing over at LinkedIn.

Stratasys’ Vice President of Corporate Social Responsibility, Arita Mattsoff, explains:

“We use 3D Printing interchangeably with Additive Manufacturing, in most cases. Both represent the same – producing additively rather than subtractive. We tend to use AM more than 3DP in the context of manufacturing and production of final parts and products, and also in the context of tooling by AM. Rapid Prototyping is an important term for us, describing the RP part of manufacturing, describing prototyping using 3D printing. While 3DP and AM represent the entire process of manufacturing – from RP to tooling to production.”

Evolve Additive Solutions Chief Business and Marketing Officer Bruce Bradshaw agrees, adding:

“At Evolve we use Additive Manufacturing when we refer to our technology as it tends to separate STEP from the low-end desktop 3D printers.  As Arita said and others have said, we look at AM as more manufacturing and 3D printing as prototyping.”

Of course, there is room for nuance when it comes to which technologies specifically are referenced as ‘printing’.

James Reeves, Managing Director of voxeljet UK, says:

“We use 3D Printing for our technology because we use inkjet print heads – we are printing. I would say 3D printing is a type of Additive Manufacturing. Many of our customer still refer to 3D printed parts as ‘rapids’.”

Xaar Technology Specialist Gareth Neal notes:

“I dropped the ‘Rapid’ from Rapid Prototyping as it’s just the speed things are done now.  I use Additive Manufacturing for parts that are end product, made to a specification. 3D Printing covers everything else. And also, all of the above for the uninitiated in casual conversation. It doesn’t always
help that there is a conflict sometimes between marketing to new users (in which case, 3D Printing makes sense – even if it’s not really ‘correct’) and using a more relevant nomenclature. In the end, the Additive will be dropped from AM and this will become ‘normal’. Another tool in the box. Of course, this is for generic cases. Internally at Xaar, we have printing, and 3D printing. As we literally print in 3D.”

When these printing-based technologies are turned to manufacturing — and for ease of conveying exactly what is offered — clarifying that through production-specific language comes into play.

Shapeways’ Chief Commercial Officer Pat Shores adds:

“This may sound funny, but lately at Shapeways I’ve been introducing ‘3D printing manufacturing’ very intentionally. As we are actively attracting people newer to the technology (especially through product design services and they just have an idea, not even a model), many think 3D printing is only for prototypes or fragile plastics. They do not realize it is end-use ready, multi-material, and viable for manufacturing. ‘3D printing’ as a term has a sexiness and an opportunity to modify it. My sense is that ‘additive’ doesn’t have that same understanding in culture. ‘Manufacturing’ in broader culture also has associations: finished product, durable, and repetitive, for example. Hence, ‘3D printing manufacturing’. Your article is so timely. I’ve given this a lot of thought lately and how to intentionally use language to make 3D printing meaningful to new audiences, while also making sense to industry veterans and those who helped create it.”

Rachel Park continues of her thoughts on nomenclature:

“3DP versus AM will not be resolved any time soon, and like many others here, I often use them interchangeably depending on application, audience and process being used. On that – I have noticed that process names (re the 7 categories identified by ASTM) are being used more frequently, to differentiate capabilities and applications for manufacturing / production.”

A consensus?

All that said, where are we now?

Well, what do you call it? I asked, Twitter answered: in a relatively short-duration poll, 71 respondents voted largely in favor of “additive manufacturing” as the prevailing phrasing:

Terminology time: which descriptor do you favor?

What differentiates usage of #3DPrinting / #AdditiveManufacturing / #RapidPrototyping in your view?

Following up for nomenclature discussion for @fabbaloo

— Sarah Goehrke (@SarahGoehrke) October 3, 2018

This was by no means a clean sweep, nor, obviously, an especially large sample size.

A throughline in each point of discussion came down to the most important part of the entire debate: clarity.

Whatever you’re discussing, make sure it’s understood. The journalists, in particular, who came together in this conversation tended to agree with 3DPBM Co-Founder and SmarTech analyst Davide Sher, who noted:

“Re: 3D printing vs additive manufacturing I do use them almost interchangeably. There are however subtle differences. I use AM mainly when referring to industrial production while i use 3D printing for things like prototyping, desktop 3d printing and for innovative applications (mostly extrusion based) such as construction, consumer, low cost and desktop applications.”

Additive manufacturing consultant and well-regarded industry expert Todd Grimm noted:

“Rapid prototyping is a use/application under the 3DP or AM umbrella, in my opinion. Regarding 3DP vs AM, I go with the flow…all depends on the audience/message.”

Audience and messaging are critical throughout this debate (and, indeed, any presentation of technology/business).

LINK3D Account Manager Christian Rice ran into a recent reminder to keep terms understandable, as he relates:

“I use 3D printing and AM interchangeably depending on the audience. For instance, at the TCT show in the UK last week I said additive manufacturing to a hobbyist and he didn’t know what I was talking about.”

His story reminded me of last spring when, leaving the in-depth, expert-driven Materialise World Summit, ahead of me in the boarding queue was a cardiac physician. As we held passports in hand to leave Brussels, both bound for our native US, we chatted about the conferences we had each attended. While discussing the presentation of another cardiac physician I had just heard, I mentioned the phrase “additive manufacturing” — too casually, it turned out, as the good doctor held his hand up and told me that if I was going to use industry jargon, he would start throwing out medical terminology.

Even as we see a strong rise in production-driven developments for additive manufacturing, and as major global corporations embrace the technology, the fact is that this fast-growing industry is still rising from a small base. While I would argue that we’re moving beyond the designation of ‘niche’, if not already beyond that, these technologies still aren’t mainstream enough for regular casual conversation about AM.

So where does this all leave us?

TL;DR

In short, clarity rules the day: use what is most understood.

Rapid prototyping is relevant when discussing the processes involved in turning 3D files into physical objects during the product development cycle, often referenced in terms of speeding new product time-to-market.

3D printing is the most popular term (and the “sexiest”, though I’ve long been fighting a losing battle on the need for manufacturing technologies to be “sexy”). Best applied to inkjet-based technologies for accuracy, but acting as a wide umbrella term, 3D printing refers to the layer-by-layer process by which physical objects are built.

Additive manufacturing is best applied to production-focused technologies. This term, like RP, can also be an umbrella term under which several processes are gathered; 3D printing can be seen to be one part of the additive manufacturing process, in addition to file preparation (including design for additive manufacturing, or DfAM) and post-processing (including support removal, any necessary heat treatments, polishing, sanding, painting, etc.).

Because rapid prototyping can involve several processes in addition to 3D printing, and additive manufacturing can be seen to refer to the end-to-end process of production in an additive, as opposed to traditional subtractive or injection, manner, and also encompasses pre- and post-processing, these two terms are broader in scope than is 3D printing, which refers to what happens on a 3D printer.

However, as any 4×4 may be called a “Jeep”, as in the above example, and any facial tissue is frequently referred to as a “Kleenex” and any medical adhesive as a “Band-Aid”, sometimes the most widely recognized terms are not the most technically correct. Several of the experts who so thoughtfully contributed to this conversation made sure to underscore the important point of gearing conversation toward audience.

Just as the hobbyist Christian spoke with and the physician I met didn’t have the background to immediately recognize “additive manufacturing” and as a manufacturing floor supervisor may not take you seriously if you suggest she bring “3D printing” into the production line workflow, using situationally-appropriate language remains key.

One discussion, one article won’t change language; for my part, and for Fabbaloo’s part, we’ll continue to use both “3D printing” and “additive manufacturing” effectively interchangeably, with distinctions based on understanding and application.

After all, what’s in a name? An additive technology by any other term may build as sweet.