Mimaki Takes on Material Jetting with 10-Million-Color 3D Printer
Michael Molitch-Hou posted on November 13, 2017 | 2565 views

The world of full-color 3D printing is an interesting place, with technologies often trading off functionality for aesthetics in order to bring more photorealism to the objects produced. Among those technologies, material jetting—in particular, PolyJet from Stratasys—has stood out for its ability to create a wider range of colors and other material properties, such as translucency and flexibility or stiffness, compared with other forms of 3D printing.

Mimaki’s first 3D printer is the Mimaki 3DUJ-553 UV LED, which cures layers of photopolymers into solid, full-color objects. (Image courtesy of Mimaki.)
Mimaki’s first 3D printer is the Mimaki 3DUJ-553 UV LED, which cures layers of photopolymers into solid, full-color objects. (Image courtesy of Mimaki.)

Now, a new challenger may have stepped into the ring to take Stratasys on with its own version of material jetting. The Mimaki 3DUJ-553 UV LED relies on Mimaki’s history as a 2D inkjet printer manufacturer to 3D print objects with a greater range of colors than any other technology in the space.

ENGINEERING.com spoke with Josh Hope, Mimaki’s senior manager of 3D Printing & Engineering Projects, who was able to tell us more about the technology.

Full-Color 3D Printing from a New Angle

Mimaki was established in Japan in the mid-1970s, where it began manufacturing large- and wide-format inkjet printers and cutters. More recently, the company has been producing machines capable of performing UV-cured inkjet printing for industrial applications.

“It was really just a natural progression to go from 2D printing to 3D printing, where we’re able to take what we know about the accuracy of dot placement, color management, color gamut, fitting corporate colors and things like that and bring it to the full-color 3D world,” Hope explained.

Mimaki is targeting the visual prototyping and modeling space with its full-color 3D printing technology. (Image courtesy of Mimaki.)
Mimaki is targeting the visual prototyping and modeling space with its full-color 3D printing technology. (Image courtesy of Mimaki.)

Other manufacturers in the space have grown out of the industrial manufacturing sector, beginning life making machines for rapidly prototyping end parts. Mimaki, however, has been established in the world of 2D printing, seeing its products presented at events like drupa (the largest 2D printing equipment exhibition in the world).

As the company approached the 3D printing market, Mimaki decided to focus more on the aesthetic applications of 3D printing, the look and feel of printed parts. These would be customers that would need to produce parts with as accurate and detailed color as possible, such as a firm that might manufacture models or figurines.

The Japanese firm isn’t the first to target aesthetic over engineering applications. Israel’s Massivit 3D, for instance, developed its large-scale 3D printer for the creation of immense marketing items and often displays the technology at drupa as well.

The 3DUJ-553

Mimaki developed the 3DUJ-553 using the UV curing technology it had developed for 2D printing. A pigmented UV-curable resin is jetted through industrial inkjet heads, which is then cured into a solid state. This allows for 3D printing full-color objects up to 508 x 508 x 305 mm (20 x 20 x 12 in) in size and a minimum layer height of 22 microns.

The printing process for the 3DUJ-553. (Image courtesy of Mimaki.)
The printing process for the 3DUJ-553. (Image courtesy of Mimaki.)

In this way, Mimaki’s technology is not radically different from PolyJet; however, one of the biggest advantages that the company brings to the space is color and color management. Unlike Stratasys’ J750, which boasts 360,000 colors and six different textures, the 3DUJ-553 can produce over 10 million colors.

The 3DUJ-553 is capable of producing over 10 million different colors, more than any other 3D printer on the market. The next runner-up would be the Mcor Iris HD, which produces 1 million colors. (Image courtesy of Mimaki.)
The 3DUJ-553 is capable of producing over 10 million different colors, more than any other 3D printer on the market. The next runner-up would be the Mcor Iris HD, which produces 1 million colors. (Image courtesy of Mimaki.)

Such a broad range of colors means that any transition between two colors can be smoother, but also that a brand will be able to produce objects with its signature pantone colors in mind. Additionally, it’s possible to make even more photorealistic parts, including skin tones, with the technology.

A diagram contrasting plaster-based binder jetting, such as ColorJet Printing from 3D Systems, with the Mimaki method. (Image courtesy of Mimaki.)
A diagram contrasting plaster-based binder jetting, such as ColorJet Printing from 3D Systems, with the Mimaki method. (Image courtesy of Mimaki.)

Hope also pointed out that, rather than simply having a single, generic color profile that is used on all of its 3D printers, the company can leverage its Mimaki Profile Master software to manage color characteristics with specific profiles. These profiles can be leveraged across a fleet of machines so that all of the systems are producing parts with the exact same colors.

“We’re really focusing on this being a color-managed device,” Hope said, “so that you can get the same accurate color produced on the first machine replicated on the next five machines. You can move from the prototyping stage into production in a much more predictable way.”

A graphic from Mimaki’s website illustrates the ease with which supports can be removed without any harsh chemicals. (Image courtesy of Mimaki.)
A graphic from Mimaki’s website illustrates the ease with which supports can be removed without any harsh chemicals. (Image courtesy of Mimaki.)

The 3DUJ-553 also uses a unique ink for printing support structures. Jetted from the same nozzles as the primary resin is printed, the support material is automatically calculated by the system’s software, which knows where support should be placed and how much to apply.

Once the print is complete, the support, which has a waxy consistency, can be crumbled away by hand before being placed into an ultrasonic bath of plain tap water. Some heat and vibration from the cleaner causes the material to wash away. This differs from competing systems, which may require a water jet and a harsh sodium hydroxide bath.

Mimaki’s technology doesn’t have the same texture production capabilities as PolyJet, however. It is able to 3D print translucent parts, but stiffness and flexibility are limited. According to Hope, there is some flexibility possible, depending on the ink used.

“We’ve done some testing with eyeglass frames where the core material that we print with is either clear resin or pigmented with white. If we use the white, it’s a little bit more rigid. If we use the clear, there’s a bit more flexibility with it,” Hope said.

Through Mimaki’s expertise with industrial 2D printing, the company is able to bring two other benefits to the machines that are associated with maintenance and management: an ink circulation print head and nozzle check unit (NCU).

Ink is circulated throughout the head to prevent sedimentation from occurring. (Image courtesy of Mimaki.)
Ink is circulated throughout the head to prevent sedimentation from occurring. (Image courtesy of Mimaki.)

“When you have pigment inside of the ink, the pigments tend to settle down. White ink is a really good example of this because white uses a titanium pigment that is very heavy. If it’s left in a static state, it will settle to the bottom of an ink head,” Hope explained. “With the Mimaki machine, the ink circulation system circulates the ink through the supply tanks, the ink line and the secondary tanks and all the way through the ink head itself. That circulation helps to keep the pigments in the ink suspended, so you can have a much truer color and a more consistent color and you don’t have issues with inkheads clogging.”

A sensor on the print carriage can detect when a nozzle is not depositing, so that the printer can compensate for the issue during printing and go through a cleaning. (Image courtesy of Mimaki.)
A sensor on the print carriage can detect when a nozzle is not depositing, so that the printer can compensate for the issue during printing and go through a cleaning. (Image courtesy of Mimaki.)

The NCU is a unit attached to the print carriage that is able to sense which print nozzles are firing and which are not. If a nozzle isn’t firing, the machine can go through a cleaning process or the software can compensate for the missing nozzle. For instance, if one nozzle is out, the nozzle next to it can take over and both fire where it’s normally supposed to fire and fill in for the missing nozzle. That way, the print will have consistent colors without any lines of missing ink or other print issues.

The Future for Mimaki in 3D Printing

Though visual prototyping is a clear target for Mimaki entering the 3D printing space, the company envisions customers finding new and unique applications for the 3DUJ-553.

“In the past, we have developed products with a very specific end use in mind only to find that, once that product was in the market space for months or a year, customers are using them in very different ways than we had envisioned,” Hope said. “We’re really excited to see what the market does with the technology from when customers begin using it.”

Given Mimaki’s diverse portfolio of 2D printers, there may be a number of possibilities for future products. For instance, the company manufactures both smaller- and larger-format machines that could influence future 3D printers.

“Our flatbed UV products basically have the same technology as the 3D printer in a 11.5-x 16.5-in bed all the way up to an 8-x 10-ft bed, so that scalability up and down is definitely something that we have the ability to do,” Hope relayed.“In initial conversations with customers, we’ve discussed this being a much larger or a much smaller machine, such as one that would more easily go through a standard office door.”

Mimaki obviously isn’t the first 2D printer manufacturer to enter the space, with HP currently dominating headlines. Neither is it the last, as Epson has recently announced that it will be developing an industrial 3D printer.

In fact, companies with ties to 2D printing are peppered throughout the space, though it may not be immediately obvious. XYZprinting is the Taiwanese subsidiary of New Kinpo Group, a contract manufacturer that makes a wide range of 2D printers for brand-name clients. The company has leveraged this expertise to release its own binder jetting and material jetting systems. The former deposits colored ink onto a bed of gypsum powder, similar to 3D Systems’ ColorJet Printing, and the latter cures monochromatic, photosensitive resin akin to Mimaki and Stratasys’ technologies.

Stratasys itself has its PolyJet roots in the 2D world from Objet, the Israeli company that merged with Stratasys in 2012 and brought PolyJet with it. Before Objet was established, many of the staff came from industrial 2D technology. Since the merger, co-founder Hanan Gothait went on to create XJet, which uses inkjet for metal 3D printing. In fact, the whole region where Objet was founded is populated by inkjet experts, including Nano Dimension, which uses inkjet technology for electronics 3D printing and bioprinting.

The reason I list these examples is that they attest to the flexibility of inkjetting technology, meaning that, this year, Mimaki may have a machine dedicated to full-color models, but the future may be open to anything from Multi Jet Fusion–style printing to metal or electronics. But, before I get ahead of myself, let’s see how the 3DUJ-553 works out.

For more information about the new technology from Mimaki, visit the product website.


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