Researchers at the National Taiwan University of Science and Technology (Taiwan Tech) have developed a method for inkjet 3D printing in color. The method creates a 4 color mix capable of achieving the same 300 pixel per inch resolution found in photographs.

Color palette 3D printed in resin using Taiwan Tech's method. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang,

Color palette 3D printed in resin using Taiwan Tech’s method. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang

From 2D paper to 3D objects

Taiwan Tech method operates on the same principle as traditional 2D printing, i.e. droplets of colored ink are jetted out on to a surface. The process becomes 3D by using resin inks that can be cured using UV light. These inks are then printed layer by layer until a 3D object is created.

The process uses the same piezoelectric control of 2D inkjet printing in 4 different print heads.

4 piezoelectric heads of the Taiwan Tech 3D inkjet printer. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang

4 piezoelectric heads of the Taiwan Tech 3D inkjet printer. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang

The benefit to using piezoelectricity to deposit the ink is that it gives greater control over the droplet size, which in turn affects the resolution of the printed image. However as the study explains,

A proper piezoelectric driving waveform must be designed to match the property of each color resin which is developed in this study. It is necessary to enable the piezo head to jet out the required ink in right amount

After slicing the desired 3D model for printing, a color profile for each slice is then identified using four primary colors: cyan, magenta, yellow and white (or CMYW). The programming stage also takes into account the layering of these colors on top of one another to create the right finished effect.

3D images 3D printed in layers at Taiwan Tech. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang

3D images 3D printed in layers at Taiwan Tech. Figure via M. J. Tsai, Y. S. Hsu, Y. L. Cheng, F. Chen and C. H. Chang

The conclusions of the study desire more control over the droplet size to create finer quality prints. The authors also state,

It is expected that a colorful three-dimensional object with CMYWK and supporting material can be fabricated by involving more piezoelectric heads and Photo-curable processing design in the near future.

3D printing with color and piezoelectricity 

As traditional inks are the product of many years of development, it makes sense that a method of inkjet printing would be the way forward for 3D printing in color. This sentiment is adopted by Irish 3D printer company Mcor who use the selective deposition lamination (SDL) method of 3D printing with layers of paper.

Piezoelectric nozzles are also used in 3D printing pharmaceutical products. Piezoelectric control can also be used to 3D print in metal, as in Japan’s Super Inkjet Technology (SIJT) Inc.

Development of a color photo-curable 3D printing mechatronics system by using multiple piezoelectric heads was presented at the International Conference on Machine Learning and Cybernetics (ICMLC) 2016 in South Korea. The supporting paper is published online here. It is co-authored by Ming-Jong Tsai and Yu-Sung Hsu of the university’s Graduate Institute of Automation and Control, and Yih-Lin Cheng, Freeman Chen and Chih-Hsuan Chang from the Department of Mechanical Engineering.

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Featured images shows a CMYK color palette in the order: Magenta/Yellow/Cyan/Key (grey & black) Palette by Flain4399 on color-hex.com

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