Color 3D printing is a bit of a rarity in today’s world, but it does exist and can be done in several ways.
When I say “full color 3D printing” it’s quite different from “multicolor” 3D printing. There are on the market today many different multicolor (or indeed, multimaterial) 3D printers that simply have a choice between a few colors (or materials). These are most often a filament-powered 3D printer that accepts two or more input filaments, which can be different colors.
In such equipment the hot end can act either extrude one of the input materials alone, or a mix of two or more input filaments by spreading out the feed speed between extruders.
In such equipment it’s theoretically possible to have the machine produce any given color through this mixing process. But in practice it’s entirely impractical as any color switch means the hot end must spend time purging itself of the previous color mix. Purging also wastes material, sometimes a considerable amount.
The color switch process means these machines cannot produce varying colors, like a gradient, in arbitrary ways. Thus they are limited to what might be called “spot color”, where whole sections of a 3D print are a uniform color.
But what if you needed to 3D print a “full color” that included rich textures and gradients in a way that mimicked reality? It turns out there are some 3D print options, but not many. Let’s take a look at them.
Stratasys offers their J750 PolyJet technology. This was the ultimate result of their PolyJet evolution, which is a process combining inkjet deposition of photopolymer resin and UV light exposure.
Their latest system involves seven different resins that can be dynamically mixed to create virtually any color, including a pure clear material. Their color 3D prints are wonderful, and in some cases will fool you into believing they are real objects – until you pick them up.
The drawback to the J750 system is that the cost to acquire and operate the system is considerable and may be out of range for many businesses.
Mimaki’s process is similar to Stratasys’, as they also use a resin-based system. However, Mimaki is a long-time producer of large-scale 2D print systems for industry. Their experience with color in general has translated very well into their 3D printing system, where they boast of the ability to reproduce colors quite accurately.
It does work; the Mimaki samples I’ve seen are incredibly realistic. They may have the best quality color prints available at this time.
Mimaki’s pricing is actually somewhat less than Stratasys’, although still at levels that may prevent a usable business case from being developed by some businesses.
3D Systems has a very old and well-regarded full color 3D printing process. They acquired it some years ago from ZCorp during a takeover. The process is quite different from that used by Stratasys and Mimaki, and employs a powder / binder jet process.
A flat bed of powder is traversed by an inkjet system that selectively drops liquid binder – and the binder just happens to be colored in the same way as 2D inkjets. Thus they are able to gradually build up a full color object. However, the colors are not as vibrant or have the resolution of the Stratasys or Mimaki solutions. Clear material is not possible on their system.
Rize’s XRIZE approach is different from the others in that they do use a filament-powered system. The difference is that they employ a six-color inkjet system that can selectively splash color on each layer of a print as it takes place.
The resulting objects have very good full color, but not quite as good as Stratasys or Mimaki. Because of the filament approach, Rize is unable to produce clear material, unlike Stratasys or Mimaki.
An interesting feature of the XRIZE system is that one of the inkjet colors slots is used to deposit a special “release” liquid that prevents support material from fusing with the model itself. This makes post-processing a breeze as support material almost falls off itself.
One of the newest entrants to the color 3D printing space is HP, who have adapted their powerful Multi Jet Fusion (MJF) technology to produce full color 3D prints.
The key to their color capability is the voxel-level control allowed by MJF. In MJF an inkjet mechanism can deposit – per voxel – up to eight agents. These are liquid droplets that can take on many different characteristics. You might have agents that bind the material together, for example, or create support structures, or create electrical conductivity – and finally – create colors by mixing CYMK inking agents.
Agents, combined with the voxel-level control, allow HP’s MJF systems to print full color textures: the color gradients can be adjusted voxel by voxel, just as is done with pixels on 2D color systems.
Mcor Technologies has what might be the most unique process of the bunch, as they use plain paper for their material. A sharp CNC-controlled blade slices the edge of the object at each paper layer. The machine glues each paper sheet together and forms an object that is released by removing the cut portions after printing.
How do they produce color? They incorporate an inkjet system that pre-prints each paper sheet before it’s sent in for gluing and cutting. The inkjet prints a few millimeters of appropriate color where the cut is to take place. When the sheets are stacked together, you have a fully colored object. Clear material is not possible.
However, the color quality isn’t quite as good as the other processes above, but to compensate the price of the Mcor system is significantly less, and especially for their material: paper.
One more option is available from XYZprinting, whose da Vinci Color device uses a combination of filament extrusion and inking to produce full color prints. The device seems to tint the filament just as it enters the hot end, where it is then extruded to produce the desired color.
The print results are indeed colorful, but the color is not particularly accurate and most shades have a kind of transparent look to them. However, the XYZprinting full color 3D printing solution might be the least expensive option on our list.
Why use full color 3D printing at all? Many 3D print operators scoff at full color printing as it is rarely requested and the parts produced are often fragile.
That’s not what it’s about at all. While most 3D printing is used to prototype mechanical parts used in stressful situations, full color 3D printing is not testing mechanical prowess.
Instead, it’s testing how something looks. Prototyping the visual, not the mechanical. It doesn’t have to be strong.
An example scenario might be found at a shoe manufacturer, where 100 different shoe designs for next fashion season are produced in CAD. These are all 3D printed in full color, where those in charge can inspect them to select the winning models for production.
Whichever full color 3D printing solution you choose, be sure to match your budget and requirements.