As 3D printing technology evolves, chances are you will soon be considering whether you need a color or monochrome unit. Several color 3D printers are available but each uses different technology to deliver color. Here’s a closer look at the differences.

By Joe Titlow, Senior Director of Product Management, 3D Systems

Several 3D printers are available that give you the option of seeing your part in one or more colors. Each printer, though, handles color differently. Understanding these differences in color delivery will help you decide which one is right for you.

There are 3 basic categories of color 3D printers:

1) Color-choice printers that print one color at a time, but are capable of different base colors;

2) Basic-color printers that print a few colors together in one part, but in limited color choices;

3) Full-spectrum color printers that can print thousands of colors and can differentiate at the pixel level.

Color-Choice Printers

3D printers in this group have the ability to print parts in a variety of colors, one color at a time: the color of the build material. Switching between colors requires an operator to switch the printer’s material from one type to another before any given build. An example of this is the ProJet 1500, by 3D Systems, which combines color capabilities, fast build speed, and high-resolution printing. This printer lets you select from a library of six vibrant colors for the parts it creates. You can choose the one that best matches the intended color of the final part, or a mix of colors in an assembly composed of several distinct parts. The ability to distinguish the different pieces of an assembly improves the communication value of the parts and expands your creative options.

Basic-Color Printers

3D Printers in this group let you print several colors within the same part, automatically. The Bits from Bytes Touch Color from 3D Systems and Connex printers from Objet fall into this group even though they accomplish this multicolor performance through different means. Both printers produce a handful of different colors within the same part, which allows for a couple of interesting uses of color. In addition to being able to identify different parts of an assembly inside of a single print (like buttons on a remote) they also begin to allow for some basic part labeling (like including text in a different color).

Full-spectrum color printers

The only 3D printing technology available today to print the full spectrum of colors, all within the same part and addressable at the pixel level, is the ZPrinter, by 3D Systems. ZPrinters achieve the same type of color on 3D printed models that color document printers display on paper. They produce color by automatically mixing the inks in hues of cyan, magenta, yellow, and black on the fly, during printing. This process results in up to 390,000 unique colors and a virtually infinite number of color combinations, enabling 3D printing in almost any color a customer desires.

ZPrinters bring color down to the pixel level – at high resolution – resulting in incredibly lifelike models. This approach is full-spectrum color 3D printing. In addition to putting lifelike colors in all the right places, the 3D printer can apply photos, graphics, logos, textures, text labels, finite element analysis (FEA) results and more, and can produce very lifelike models where it’s difficult to distinguish the prototype from the real product.

 

How full-spectrum color 3D printing works

To print in color, ZPrint software accepts a digital 3D design file that contains color information (in addition to geometry information) just as a Microsoft Word or PowerPoint file contains the color information for a document printer. Since rapid prototyping’s traditional .STL file format includes no color information, ZPrinters accept several other file formats that do, including .3DS, .WRL (VRML), .PLY and .ZPR. 3D Systems’ ZEdit™ Pro software gives you another chance to add color, colored textures, and labels to the 3D model files before printing.

Like a document printer, the 3D printer converts any color from the RGB (red, green, and blue) space used on a personal computer to a CMYK (cyan, magenta, yellow, and black) color value for printing. It then orders up the right combination of CMYK drops to be placed in the same area, using either patterns to blend these drops of color into any composite color. To minimize operating costs, the 3D printer colors only the exterior of an object, not the hidden interior volumes, using ink only where it’s visible.

ZPrinters benefit from a heavy R&D investment in color science to maximize the gamut of colors they can produce. These capabilities have progressed steadily since multicolor 3D printing was introduced in 2000. Today, ZPrinters can produce 90% of the colors on the Adobe® Photoshop palette – which is nearly as powerful as a high-definition color photo printer.

The power of color

Full-spectrum color 3D printing can make a difference in a prototype when it comes to realistically conveying the finished look, distinguishing between parts of an assembly, or displaying FEA results. Color is absolutely necessary for some applications in geographic information systems (such as 3D maps), retail, entertainment, healthcare and more.

We sometimes forget that color goes beyond creating a lifelike look and can deliver important supplemental information that monochrome just can’t, including strength information, designer details, manufacturing steps, brand identity and more. In this way, full-spectrum color 3D printing expands the usefulness and value of a model across the organization.

While a monochrome document printer seems to print black and white, it only prints black. The paper gives the white. A color-choice 3D printer, however, has no background for contrast – its “print color” is the same as the material color. You need at least a basic-color 3D printer for something like text or engineering labels, even if you want them to be “black and white.” However, basic-color systems may not achieve high-resolution text since the color does not vary from pixel to pixel.

Full-spectrum color 3D printing also makes it quick and easy to color-code parts or add symbols. Arrows and other highlighting techniques are helpful for design reviews. Green, for instance, can spotlight what has changed in the latest iteration of the part. Designers can add shadows to enhance understanding. When a complete design is ready to be transferred to manufacturing (or a supplier), different colors or patterns can convey information such as assembly instructions (for example, assemble blue parts first, red second and yellow last). Colors can also highlight part surfaces that need to be machined (such as holes that need to be drilled).

Data analysis is another area where multiple colors can offer tremendous value. Although FEA produces bold colors on a flat computer screen, it tells a much richer story on a model that can be passed around a design review. Thermal analysis, stress/strain analysis, geological analysis and more can now be applied to a physical 3D model in multiple colors, vividly representing the data for better understanding.

Improved printing resolution means more precise application of colors. For example, a soft drink company can now design and print various versions of can labels directly onto a can model with enough detail to read the ingredient list and make the bar code scannable, which requires colors available on the pixel level.

Texture maps are another option possible only with full-spectrum 3D printers. It’s easy to apply graphics to a model that simulates wood, bricks, metal, fabric, shadows, bumps or any other texture. You can do it directly in your CAD package or apply it with ZEdit Pro.

Other cool applications

Full-spectrum color has helped 3D printing move beyond manufacturing and architecture. Topography and other geographic information systems (GIS) data are useless unless you can apply lines, labels and colors to a 3D-printed terrain. With full-spectrum color 3D printing, you can print highly detailed mountain and cityscapes, clearly indicating water, buildings, pastures, forests, roads, utilities, and more. LandPrint.com, for example, uses ZPrinting technology to generate 3D maps on demand, transforming satellite imagery into physical 3D landscapes.

Hospitals like The Walter Reed Army Medical Center use ZPrinting to save lives. Doctors are improving the success of delicate surgeries by using 3D printed models as a roadmap for treatment. In orthopedics, for example, a model can be created for removal of bony growths on a patient’s knee. Specialists can 3D print a white model of the joint with blood vessels highlighted in red and a nerve in yellow, enabling the surgeon to determine safe routes of attack on the tumors.

Scholars like those at Cornell University use ZPrinting to preserve ancient artifacts. Researchers study Sumerian and Babylonian cuneiform tablets as 3D printed models, learning more than they would from photographs, preserving the originals from damage, and enabling more students to examine them.

Colleges and universities are using the multicolor capability of ZPrinters to extend 3D printing value beyond the engineering department into fine art, architecture, civil engineering and other areas of study – stretching technology dollars.

Gamers who play World of Warcraft are bringing their imagination into the real world through multicolor ZPrints of their personalized avatars.

These are just a few of the new ways that true full-spectrum color 3D printing is changing the way designers design, architects build, doctors heal and students learn. MPF

3D Systems
www.3dsystems.com