By Melissa Donovan
As technology users, we often take for granted what goes on under the hood of the printer. Truthfully, it’s a carefully orchestrated mix of internal components that ensure an optimal functioning product. Printhead and ink manufacturers work in tandem to eliminate challenges like clogging, ink jetting properly, and incorrect drop sizes.
Above: Once Xaar confirms that the ink is compatible with its printheads, it sets out to ensure it is also compatible with the ink systems.
Ink and physical parts manufacturers collaborate to create an efficient printing system.
With ink development, ink manufacturers must work with material suppliers. “For new ink development, we often incorporate materials from a specialist to provide improved performance. Before we incorporate a new material, we evaluate it for safety, cost, and assurance of supply. We work with the supplier to determine its purity and variation over time. Then test the product performance with storage stability, robustness to nozzle clogging, and resistance to resistor fouling,” says Noëlle Peutat, worldwide large format strategic environmental lead, HP Inc.
On the hardware side, James Pattison, product owner – ink systems, Xaar plc, believes that by collaborating with ink manufacturers, “we help them to tailor physical properties like viscosity, surface tension, and density to match the operating window of the printhead. This ensures optimal drop formation, drop velocity, drop placement, and jetting reliability, which ultimately dictates overall printing performance.”
Of course, it’s beneficial when said manufacturer is involved in both ink and the physical parts, like Epson, for example. “The development of the ink and the printhead simultaneously as a system provides the best optimal functioning product by assuring reliability, that all chemistry is compatible, and that the system will function as expected by customers,” explains Reed Hecht, group product manager, Epson America Inc.
Collaborating with third parties is also important, even if you manufacture everything in house. “Epson works with third parties to enable them to drive the printer through a software development kit that will help their software with the more complex aspects of driving the printhead—drop size selection, screening—to further optimize the print quality and assure reliability,” says Hecht.
“We partner with both printhead manufacturers as well as printer manufacturers, often from the earliest stages of design or fabrication to ensure that we are optimizing the capabilities of the fluids to run on these platforms. All while taking full advantage of the printhead or printer to offer the best possible output in terms of speed and quality. This includes matching the ink to printer parameters through waveform optimization or other means. The key is to provide optimal functioning without over engineering the ink so that we can provide output that matches the technical capabilities of the printhead and printer,” explains Nitin Goswamy, president, A.T. Inks.
As an ink developer and manufacturer, DuPont collaborates with OEMs to formulate ink sets that deliver the printed image and process behavior that their customer needs to have for successful print results. “The process is iterative, with initial assumptions and ink specifications that will be tested, both on laboratory equipment such as jetting rigs and on the targeted printer,” shares Eric Beyeler, marketing manager, Artistri Digital Inks, DuPont Electronics & Industrial.
Sun Chemical is a major supplier of pigment and inkjet dispersions. This allows the company to create and modify building blocks of ink and optimize the pigment and disperant interactions to ensure consistent particle sizes and stable viscosities. “Working with the best dispersion equipment manufacturers and custom designing disperation processes, combined with formulation expertise, creates the best performing inks and most stable products for digital printing,” says Phil Jackman, global product manager, digital, Sun Chemical.
Multiple considerations go into developing ink for ink systems and vice versa.
Ink impacts many areas of a printing system, admits Peutat, such as material compatibility, reliability, and print quality. “For this reason, new ink development is complex, so we need to be sure of significant improvements to performance to justify the investment. In developing a new ink we target key attributes to improve and key attributes that cannot be degraded. It is easy to improve any one factor but difficult to do so without degrading another.”
Inks are primarily developed for particular applications or for optimizing output based on the technical limitations of the ink delivery system, notes Goswamy. “Generally an ink is designed for a printhead or a few printheads with similar functioning range. The foremost factors in deciding the design of the ink is the nature of application and the printing reliability.”
He provides an example of the design between an ink used for scanning and single-pass printing applications. “Printheads from different manufacturers have different tolerances and the ink needs to be designed with these factors in mind. As the printers become more complex, the ink design becomes that much more challenging and the design tolerances become narrower. Once the design is over, ensuring manufacturing consistency of such inks is also a challenge and not all manufacturers have such capability,” continues Goswamy.
“Consideration must be taken of the application—substrate, printed image lifecycle, color gamut, and durability; the equipment used—continuous printer versus sheetfed, printhead type, drying equipment, and post-printing handling requirements; and the targeted productivity—line speed, run duration, and frequency of equipment usage. These considerations often lead to conflicting choices as for example increasing pigment content to deliver high color intensity can lead to poor jetting, clogging nozzles, and even printhead failure,” says Beyeler.
Epson goes through a long and all-encompassing development process to assure that every aspect of the internally developed ink technology like viscosity, chemistry, and environmental characteristics are matched optimally with the printhead technology including structure, chemistry, channels, and piezo deflection, shares Hecht.
Once Xaar confirms that the ink is compatible with its printheads, it sets out to ensure it is also compatible with the ink systems. “This involves two elements—firstly, proving that the materials involved are compatible with one another. This means the ink does not change the integrity of the materials in the ink system, and the ink system doesn’t change the integrity of the ink. Secondly, proving that the ink system can deliver ink to the printheads reliably, which may also include recirculation,” explains Pattison.
When it comes to material compatibility, Xaar designs its ink systems to work with all ink/fluid types that can be printed with its printheads. “The choice of materials must be carefully considered. All the materials we select go through a minimum 12-week materials compatibility test with a range of ink/fluid types,” continues Pattison.
Performance is also important. “We want to make sure that the homogeneity of the ink is maintained during use, so that what is put into the ink system is the same as what comes out of the printheads, and that the pressure, flow rate, and temperature of the ink can be maintained at the desired levels while printing,” shares Pattison.
All components of the ink and the physical system should be assessed, advises Jackman. This includes tubing, tanks, filters, connectors, and o-ring seals. “Any changes can be detrimental to print performance or may even cause expensive and catastrophic component failure.”
In the last five to ten years there have been several changes in the physical makeup of ink systems driven by trends like increased productivity, regulatory requirements, and cost.
The major trend in both aqueous and UV printing is the increase in speed and productivity, notes Goswamy. “More manufacturers are moving towards single-pass printing machines. The capability of scanning machines is also increasing with a larger number of printheads included in the scanning array. As the market tries to convert more analog into digital, increase in speed is important to bring down cost and improve productivity.”
He explains that with printers becoming faster, the increase in productivity means an adjustment in quality in order to optimize performance is critical. “Some ink manufacturers had to sacrifice color density and reliability to optimize speed. This caused the customer base to stratify between those who are looking at speed and high production and those that are more focused on quality. There is a happy medium between speed and quality that covers the bulk of the printers, but you do find examples on both extremes of the spectrum.”
Environmental regulatory requirements is another trend. Peutat believes it is the number one trend in the industry at the moment. “With print businesses seeking ways to take on ambitious jobs without compromising on environmental impact, ink type is a key component when putting together a sustainable offering.”
“Changes in the physical makeup of the inks are driven by regulatory pressures. Various regulatory agencies worldwide take leadership in this approach and the ink manufacturing world continuously adjusts to comply without compromising performance,” admits Goswamy.
Jackson agrees, citing sustainability as a trend in many areas of print, “where the aim is to use more renewable materials in more efficient ways. In wide format printing on paper or other porous substrates there is a move to aqueous systems. The poster markets have experience a rapid adoption of aqueous ink technology.”
Cost is always a primary driver, states Pattison, especially where recirculating ink systems are concerned, and this pressure has increased over the last ten years. “However, most users recognize that the additional reliability delivered by recirculating ink at a high flow rate far outweighs the cost of the ink system you need for the recirculation,” he continues.
“In textile, commercial, and packaging, brand owners are looking to improve sustainability and reduce the length of the supply chain. In addition, the demand for short runs is increasing as is demand for variable data or images to be included in the garment, document, or package printed. The transition to digital printing provides cost-effective answers to these trends,” notes Beyeler.
It’s an intricate combination of many complicated pieces that create a functioning wide format digital printer. Ink as well as hardware manufacturers work together to achieve perfect harmony.
Oct2022, Digital Output