"Perspectives", a monthly column authored by
Todd Grimm and Terry Wohlers
for "Time-Compression Technologies."

This column was published in the
May 2001 issue. For more great articles,
visit the "Time-Compression Technologies'"
Web site at www.timecompress.com.

What's in a Name?

Todd Grimm and Terry Wohlers

There has been a great debate in the rapid prototyping industry for nearly a decade. The topic is not the best systems, materials or processes. The discussion is not about the best ways to apply the technology. The debate is over something as rudimentary as a name and its definition.

"Rapid prototyping." The originator of this term should be congratulated for devising a name that is so attractive, exciting and well accepted. The attractiveness and generic nature of the term makes rapid prototyping an irresistible name for a wide variety of businesses, industries and technologies.

With so many disparate processes using the term, rapid prototyping has become diluted and is losing a sense of clarity and meaning, especially to those new to the rapid prototyping industry. To fix this problem, new names and definitions have emerged, and will continue to develop, at least as it is seen from our perspective.

Rapid Prototyping Defined

So, what is rapid prototyping? If a poll were conducted, there would be a wide variety of definitions and some controversial claims.

Some state that rapid prototyping is defined as a process that creates parts in an additive, layer-by-layer manner. In the Wohlers Report 2000, the definition is listed as "A special class of machine technology that quickly produce models and prototype parts from 3D data using an additive approach to form the physical models." This is the "classic" definition, one that describes the systems and technologies that created a new industry in the late 1980s.

The broader definition applies to nearly any prototyping process that is executed faster than historically expected. In this loose definition of rapid prototyping, any process or technique that generates prototypes quickly is deserving of the rapid prototyping moniker.

Neither definition is wrong or inaccurate. Both views are acceptable, and that is what creates the problem and confusion.

Loss of Meaning

Scan any design or manufacturing publication and the phrase rapid prototyping will be seen in many advertisements and articles. Some of the messages apply to the "classic" rapid prototyping systems. Others loosely use the term for every conceivable application: vacuum cast urethane parts from silicon rubber molding, investment casting, tool making, machining and even scanning systems for reverse engineering.

The attractiveness of the name has led companies of all disciplines to adopt rapid prototyping in their message. Some chose the term simply because it is the latest buzzword. Others have elected to use rapid prototyping to convey that the company has kept pace with technology or to assure prospects of fast delivery.

Rapid prototyping loses even more of its meaning when reviewing applications outside of mechanical engineering and product design. In a recent marketing newsletter, an article was titled "Rapid Prototyping." Within the article, the author discussed the advantage of rapid prototyping website designs and structure -- not exactly what those familiar with SLA, SLS, and FDM would have expected.

With such a diversity of definition, the name cannot stand on its own. People are most comfortable with labels that clearly and concisely provide meaning. And rapid prototyping is no longer clear or concise.

Change is Challenging

Even though the definition is varied and the application of the term diverse, rapid prototyping continues to be the commonly used term to describe processes like stereolithography, selective laser sintering and fused deposition modeling. And it will continue to be used to describe these technologies for years to come.

Rapid prototyping will not be easily displaced. It is a well established name that is both attractive and commonly used. Consider the many conferences, publications and organizations that use it. There is the Rapid Prototyping Report newsletter, the Rapid Prototyping Journal academic publication, SME's Rapid Prototyping & Manufacturing conference conducted by the Rapid Prototyping Association of SME. Several associations and service providers use rapid prototyping as a part of their name, including the Global Alliance of Rapid Prototyping Associations (GARPA). This list goes on and on.

The difficulty in moving away from this name has been demonstrated by past attempts to rename the industry and its technologies. Alternative names have included:

  • Free Form Fabrication
  • Solid Freeform fabrication
  • Automated Fabrication
  • Solid imaging
  • Additive Manufacturing
  • Layered Manufacturing

These alternatives have been proposed but have been greeted with little enthusiasm and support. Although each has some merit, only small pockets of individuals have elected to use these names, and they are far from achieving general acceptance and wide spread use.

Yet, within the realm of rapid prototyping, there has been some success with new names. These labels apply not to rapid prototyping as a whole but to classes of technology within the rapid prototyping industry. Examples include:

  • 3D printers
  • Concept modelers
  • Direct metal deposition

With the commercial release of new technologies and the creation of new applications, new names have emerged. These widely accepted names demonstrate that individuals desire clearly defined labels.

To further demonstrate the need, and the difficulty, to generate a widely accepted name, consider the "high-end" rapid prototyping systems. If 3D printing applies to quick, low-cost systems, and direct metal deposition applies to systems that directly produce metal parts and tools, what label exists for the SLA® 7000, Sinterstation® 2500plus and FDM® Quantum? The only term applied to systems in this class is rapid prototyping. When rapid prototyping is used to describe both a general class of technology and a specific subset of that class, discussions can become confused and complicated.

Alternatives for the Future

Since people adopt terms that provide clarity, new names and definitions may follow protocols that have been long established. Within the manufacturing, computer and software markets, there appears to be an unwritten guideline as to the naming of new processes.

Take a moment to consider the names and descriptive terms applied to the wealth of manufacturing processes. Upon inspection, it is clear that the majority describe a unique element of the process that differentiates it from all others. For example:

  • Molding
    • Injection molding
    • Blow molding
    • Reaction injection molding
  • Casting
    • Die casting
    • Investment casting
    • Sand casting
  • Forming
    • Hydro forming
    • Vacuum forming
    • Thermoforming
  • Machining
    • Computer Numerical Control (CNC) machining
    • Electric Discharge Machining (EDM)
    • Laser cutting and machining

In each of these examples, a significant factor of the method is highlighted in the name. This element clearly differentiates the process from all others. The other significant element is that each process is grouped with others that are similar, creating categories and subcategories. The major category offers a general classification of the technology, and the subcategory specifies the exact nature of the process.

Examples abound in related and unrelated areas of interest.

  • Computers
    • Mainframes
    • Minicomputers
    • Workstations
    • Servers
    • PCs
    • Macs
    • Laptops
    • Notebooks
    • Palmtops
  • Engineering software
    • CAD
    • CAM
    • CAE
    • Solid modeling
    • Wireframe
    • Surfaces
  • Printers
    • Dot matrix
    • Ink jet
    • Laser

The structure of categories and subcategories, combined with names that clearly illustrate what is being represented, is part of everyday life. The structure is used to describe vehicles, homes, movies and corporate organization. Why then would rapid prototyping be any different?

That difference could result from a powerful force known as marketing. Marketing has the potential to contradict or complement the category and subcategory structure. At a future time, a company -- possibly an established company in the document printer business—will commercialize an inexpensive machine. Armed with loads of consumer data, this organization may create a name like "PlasticJet" that is immediately adopted. Because of its utility and low cost, it could become the "Kleenex®" of the rapid prototyping industry.

As technology improves, a company may have a process that is significantly faster than today's rapid prototyping systems. The marketers may decide that their technology deserves a name that distinguishes it from all others. Perhaps they decide to offer "hyper-prototyping" systems. They could also chose to adopt "replicator," a term that the industry has ignored.

The name, whether it's PlasticJet, hyper-prototyping, replicator or something else altogether, could become widely used to describe the category of machine technology that we today refer to as rapid prototyping.


No one can say with certainty how the exact names and definitions will develop. Nor can a single person or company anticipate success when creating a name with the explicit intent to have it generally accepted. The industry, led by the press and the media, will influence the names and definitions based on clarity, conciseness and ease of delivery.

In the future, rapid prototyping may follow the naming conventions seen in manufacturing and other industries. Or an attractive name, such as PlasticJet, may achieve instant success and could replace the term rapid prototyping. Or, there may be surprises ahead and we find that hyper-prototyping or replicator replaces rapid prototyping.

A critical benefit of rapid prototyping is that it communicates complex designs quickly, clearly and concisely. Yet, these technologies have not developed names that do the same. What we have today is both success and failure to communicate. The bottom line is that human nature will not allow this to exist over the long term; so new names and definitions must, and will, surface as the future unfolds. But, until that time, rapid prototyping is the name that most people understand and accept.


Contact information:
printer friendly version Todd Grimm
T. A. Grimm & Associates, Inc.
3028 Beth Court, Edgewood, Kentucky 41017
Phone: (859) 331-5340      Fax: (859) 514-9721
tgrimm@tagrimm.com      www.tagrimm.com


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