Will Multicolor Flourish or Founder?

By Terry Wohlers

I have had the privilege of following additive fabrication applications, such as rapid prototyping, for more than 17 years. Over this time, many people in this industry have provided me with inputs and perspectives. Surprisingly few have expressed strong interest in multicolor models or prototype parts produced from an additive process. Monochrome parts suit them just fine, most would suggest. This may be puzzling until you understand that a large percentage of models and prototypes have been, and continue to be, used for fit and assembly checking. Also, many serve as master patterns for silicone rubber molds. Color is not needed for these applications.

"Viewpoint" is a monthly column authored by Terry Wohlers for Time-Compression Technologies
This column was published in the May/June 2005 issue.

Models for presentation are usually given to professionals for hand finishing and painting. A significant percentage is used to evaluate form and aesthetics and serve as visual design aids—nearly 26 percent, according to our research—but most people in the business have accepted the fact that prototyping processes (additive or subtractive) do not produce multicolor parts. Technology from Z Corp. is the lone exception.

I vividly recall the commercial introduction of color document printers. At the time, few believed that there would be a sufficient demand for them. The printers and supplies were expensive, resolution was poor, and colors were dull. Some even predicted their demise before they began to ship to customers. I received one of the first, a CalComp wax hermal transfer printer that offered a handful of colors and required special paper. Few device drivers were available for it, which limited the software that I could use with the printer. The bulky machine was slow and the resolution was a crude 200 dots per inch.

Color monitors also had a rocky start, but you wouldn’t consider the purchase of a monochrome monitor today. I recall industry pundits saying that very few would be able to justify the cost of laptop computers with a color LCD. Today, you can’t buy one without a color display. I’m still using a monochrome handheld—my third Palm product—but my tolerance is running thin. The fourth will absolutely be color.

Today, Z Corp. is the only company that manufactures systems that produce multicolor parts directly using an additive process. The color brightness and resolution of its new Spectrum Z510 product are nothing short of stunning. Also impressive is the company’s ZEdit software. It permits the user to position a JPG image on a 3D model and then print it. The idea is novel and a host of applications are sure to develop. An example is labeling bottles and containers for cosmetics, shampoo, and food products. Another is adding a company logo to a part. The software is also capable of adding part numbers, dates, names, scales, and other descriptive text. This will be helpful to engineers as they evaluate, test, and track versions of a new design. Similar to Magics from Materialise, ZEdit can also recognize the edges of features in a model, thus permitting a user to selectively add color.

I am convinced that color 3D printers will become popular in the future. Engineers and designers prefer to design products using a spectrum of colors, so it makes sense that they would also want to use the same colors when printing the parts. Can you imagine industrial designers limited to one color when creating new design concepts? Consider the world around us: everything is in color and some of the most interesting objects consist of multiple colors.

The widespread use of multicolor parts for models and prototypes will occur, but not without obstacles. Standard STL files—the format commonly used to move CAD model data to machines for additive fabrication—are “color blind.” In other words, the STL file format does not carry color information. Tom Clay, president of Z Corp., said that many of its customers are successfully using VRML as an alternative to STL. The VRML format captures color data from a CAD model, permitting a user to transfer it to a color 3D printer. Over time, VRML could establish itself as the de facto standard for printing multicolor parts. For Z Corp., it is well on its way.

Clay admits that accepting 3D color data from a variety of sources is not without its challenges. The source of the problem is often the way in which the design has been modeled. For example, in architecture, designs are modeled to look good on the screen and for document printing. Care is not taken to ensure that the 3D model is a closed, “water-tight” volume. A model that is plagued with holes, gaps, and other openings is lacking important information and cannot be printed, whether you’re using STL or VRML to transport the data. The problem is not necessarily a limitation of the design software, but rather the way in which an individual is using the design software. Clay believes that the solution will come from a combination of education and third-party solutions to repair the incomplete data. Also, Z Corp. has made modifications to its software to be more tolerant of incomplete data. The company is also working with the design software OEMs to help them address 3D color printing concerns.

Another obstacle to the growth of color is this: 38 companies worldwide manufactured and sold machines for additive fabrication last year, but 37 offered machines that produce monochrome parts only. For color to catch on, some of these companies will need to add multicolor capabilities to their products. It is not technically feasible to offer color in all these products, but in some instances, it is possible.

Most models and prototype parts being produced today are monochrome and old habits die slowly. It will take years for the majority of those who could benefit from multicolor to make the move. Eventually, most will.

As with nearly all emerging technologies and applications, problems and obstacles must be overcome before market acceptance can occur. Part of the challenge is technical. The other part is changing the established practices within organizations. Both will be overcome as the process of using multiple colors becomes easier, more system manufacturers support it, and the benefits of using it become obvious.

In the future, manufacturers will be pressured into offering machines that produce parts in multiple colors. If they do not, they will be at a competitive disadvantage, just as monochrome printers, monitors, and televisions would be today. If you don’t believe it, just look around.

Industry consultant, analyst and speaker Terry Wohlers is principal consultant and president of Wohlers Associates, Inc. (Fort Collins, CO). For more information visit http://wohlersassociates.com.