Issue: Volume: 24 Issue: 11 (November 2001)

Rapid Manufacturing

Over the past three years, there have been many positive developments in rapid prototyping, but few major breakthroughs. From this narrow slice of history, one conclusion would be that the technology is condemned to small, incremental changes for the foreseeable future. However, there are major trends driving the market, the most important of which is the evolution of the technology from rapid prototyping to rapid manufacturing.
Terry Wohlers

Some firms are already beginning to use rapid prototyping processes to do rapid manufacturing (RM), that is, to produce finished manufactured parts. Most of the applications involve relatively small quantities of parts. In fact, it's unlikely that RM will ever reach the production capacity of processes such as injection molding, die casting, or sheet metal stamping, but for some companies, this may not matter. Not all manufacturers produce and sell in volumes of millions, or even tens of thousands of parts.

Consider, for example, companies that produce small quantities of parts such as prosthetic devices, special medical diagnostic equipment, Formula 1 race cars, aircraft and marine products for the military, executive jets and helicopters, and products for NASA. Consider, too, the movement toward the mass customization of consumer products, where a production run will ultimately consist of a single part. For some products, like disposable razors and ballpoint pens, this is unlikely to happen. But for expensive products with longer life cycles, it is almost inevitable.

There are several barriers to the application of RM that must be overcome before the application becomes common practice. These include surface finishes that are inferior to that of production molded parts, inadequate dimensional accuracy and repeatability, part sizes that are limited to relatively small build envelopes, and the time and expense associated with removing excess resin and performing post curing operations.

Despite these barriers, examples of RM can already be found in a range of applications. For example, the International Space Station is equipped with hundreds of glass-filled nylon retainers, which were produced by Boeing Rocketdyne on a Sinter station rapid prototyping ma chine from DTM Corp., now a part of 3D Systems. The space shuttle has also benefited from the DTM process, which was used to produce sintered ducts for the craft's engines. Other applications include the use of custom-fit, clear plas tic teeth aligners (see "Digital Dentistry," October, 2000, pg. 50), which are produced by stereolithography ma chines from 3D Systems, and hearing aids built on rapid prototyping ma chines with special software from Raindrop Geo magic that uses point-cloud data to create shells that fit in the ear canal.
The rapid prototyping market grew dramatically from revenues of $99 million in 1993 to $601 million in 2000. Growth will slow to single digits in 2001, but pick up again in 2002.

These applications are proving that rapid prototyping can be suitable for production in terms of speed, material properties, accuracy, and surface finish. Moreover, rapid prototyping of mechanical CAD designs is well established and will continue to grow. And soon many other applications will follow suit. Indeed, organizations will rely on the technology for sculpture, architecture, mold flow analysis, molecular modeling, forensic analysis for solving crimes, and a variety of uses yet to be conceived.

RM will push rapid prototyping forward to greater mainstream acceptance. While revenue growth has slowed to single-digits in 2001, it will rise again to double-digits in 2002. New users will provide revenue to fund new product development. And with the advances, more users will be drawn to the technology. This cycle will create tremendous growth. In fact, with a vast majority of the market still untapped, rapid prototyping may yet become the multi-billion dollar industry that many envision.

Terry Wohlers is president of Wohlers Associates, Inc., a consulting firm specializing in engineering and manufacturing automation ( He is the author of the Wohlers Report on rapid prototyping, from which this article is adapted.