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Customization of Inkjet Head Technology

(April 2012) posted on Tue Apr 03, 2012

The future for inkjet printhead development in terms of technology and business-management trends

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By Rick Mandel

Ink advancements
My quest to find advancements in inkjet head technologies kept swaying the focus to the ink. As Work reiterated, screen printers tend not to print with one ink system for all applications and substrates, and we are asking inkjet to perform this minor miracle either, while going through a very small nozzle. Of all these trends, arguably the most important for adoption of inkjet technology, is increasing the range of jettable fluids.
As an example, in textile printing applications the use of sublimation dyes that volatilize at high temperature to migrate and bond strongly to the textile fabric to produce a water-washable image are less than desirable due to the ancillary heating and washing processes required. Using pigmented textile inks can remove some of these process requirements. Other examples are printing of ceramic inks, direct printing of conductive patterns by using metallic nano-particles, and printing of 3D plastic structures.
As technology advances, reality steps in. Using smaller and more accurately placed drops, clever image processing/ manipulation, and greyscale techniques, inkjet has reached the limit of what the human eye can differentiate.
If vanity is the resolution (drop size) of the print, producing a quality product on time and on budget is the true beauty of large-format printing. This product must have the durability required with the visual attributes for the viewing distance intended. Sound familiar? Screen printing battled the same issues with dot size for halftone printing. How do we produce a truck graphic that appears in continuous tone like litho printing? The race for fine-line printing was the vanity of screen printers. To produce such results, prepress costs rose, and the actual durability of the printed ink was in question with such small dots. Sounding more familiar? The new inkjet printheads have incorporated the variable drop size in their architecture.
Large-format inkjet printing seems to be at that same crossroads, though learning from its senior sister. Jettable inks for large format possess the similar attributes of the screen process, namely durability and the need for intense colors. White (and now metallics) compound the issue with their large particle sizes that must go through these minute nozzles. As with many processes, smaller requires advance engineering. As heads can produce smaller drops, the cost to manufacture such inks increase, as does the cost to manufacture the print heads. The smaller drop size opens markets for the equipment manufacturers, though it has little affected to the wide-format printer, other than that insatiable vanity.

Cost control
Over the past number of years, the resolution of inkjet printers across all classes of productivity has been very good. The newer head technology for variable dot size within the print enhances the resolution. So, we can say that we are just fine with resolution, and now the push is the ability to reduce the cost of operation. Fast is great, though up-time, maintenance time and cost, ink cost, etc., are the next steps that the production houses have on the radar. As the drop sizes drop, the expense increases, and keeping those nozzles open is even tougher.
Cost of operation is being addressed. Heads that can handle the different ink technologies without added problems is important. Speed and smaller drop sizes are targeted to encroach on other analog methods—flexo, offset, and other industrial applications. Our large-format world lives and dies with up time, consistency, product durability, and ease of manufacturing. The more new head advances address cost of production, the more large-format digital printing will continue to thrive.



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