Inkjet Presses

With the rapid growth of industrial-strength digital color printing systems, there has been speculation as to the future of conventional sheetfed and web press technology. Toner-based digital color has made great inroads into commercial print, but limitations on speed and width (along with unit cost) are keeping toner machines from consideration by futurists as candidates for supplanting offset presses.

But some of these same print technical gurus are betting that inkjet systems could be the chief follow-up technology to succeed both sheetfed and web offset presses—a big claim, no doubt. But steady advances in inkjet quality and speed are convincing skeptics that such speculation may be rooted in practical technological development.

Inkjet in print has been around for decades. Mead Digital, the predecessor of today's Kodak Versamark Div., retained this author to work on development projects with it as far back as 1981.

Inkjet revenues worldwide, including hardware, media, and ink—will grow to over $57 billion by 2009, forecasts I.T. Strategies, Boston—a 35% leap from 2004. While those figures cover the gamut of inkjet, used for everything from desktop photo printers to point-of-purchase displays to proofing systems and, yes, presses, they also reveal a vibrant market. And it is these markets that fund additional research and development to put inkjet on a fast track. That being said, expect some surprises to arrive in the next few years.

Growth will come in all areas of application: wide format, where it is supplanting electrostatic printers; packaging, where it opens the door to targeted runs linked to short-term promotions; traditional printing, where inkjet presses can print books or reasonable quality 4-color in high- and low-speed platforms; variable-data print and direct mail; and even in other arenas we don't even know about yet.

For the Discovery Channel set, inkjet is already used for creating three-dimensional solid models of product and component prototypes. And print-head developer Xaar reports the use of inkjet in creating wound bandages for skin surfaces, where skin grafts are jetted onto carriers, then used to help burn victims.

Inkjet technology has evolved somewhat gradually bringing higher speed, better inks and finer resolution. Beyond the now familiar inkjet proofing applications—which have attained remarkable color fidelity and resolution—two classes of inkjet appear in a pressroom:

1. Add-On and Value-Added variable-data systems, in which multiple inkjet print heads are fitted to narrow-web, sheetfed or conventional web presses;
2. Inkjet presses that have been designed to use inkjet as the sole imaging technology.

The first practical use of inkjet for volume runs arrived with Mead Digital System's monochrome model 2700, a 12´´-wide high-speed print head which was able, at 1,000 fpm, to pace the speed of slower commercial webs when it arrived in the late 1970s. This 120-dpi print head found initial use adding variable-data personalization to offset printed rolls of direct mail solicitation forms. Companies such as Webcraft (now Vertis), Standard Register and Communicolor (now part of RR Donnelley) pioneered putting this technology to work. In the 1980s and '90s, inkjet printers became commonplace in the bindery, mainly for the addressing and coding of catalogs and catalog order forms on saddlestitchers (and, later, perfect binders). The limitation of inkjet was that it was mainly a “one-color pony” (black, black or black). The resolution, both for text and images, was fairly low. So inkjet was relegated mainly to adding individual address or data lines to pre-printed color material.

As toner-based digital 4-color engines arrived in the 1990s, inkjet technology also diversified into color. Scitex Digital Printing (now part of Kodak's Graphic Communications Group) introduced Versamark, a true 4-color (CMYK) high-speed inkjet press designed to compete with color toner machines. A small group of print gurus, whose business it is to peer into the future, maintain that it is this inkjet technology that could be the successor to offset. Indeed, 2006 promises to be a banner year for inkjet with many introductions of several new systems.

If we look at where inkjet fits into today's commercial, variable-data and packaging markets, we find that the applications are diverse indeed. Perhaps the single greatest advance in ink and print-head technology in recent years has been the introduction of improved drop-on-demand print heads and UV-curable inks.

The prime component of any inkjet printer is the ink. Ink type dictates the ability of the printer to deal with different substrates, the printer's reliability, and its speed capabilities. Most important for the inkjet printer manufacturers, the ink is the razor-blade to the printer's razor. Ink is the profit key, with terrific margins, and holds an ongoing supplier relationship with the customer.

Inks break down into water-based, solvent-based and UV-curable (which may be water-based). Printer design also dictates which inks can be used. Continuous array printers can use water-based and solvent inks (see sidebar at left). Dyes used to make the ink are incredibly concentrated. Evaporation is an issue, and air bubbles generated by the vibrating piezo crystal(s) are an enemy of good printing. The ink chemist's job is not an easy one.

Kodak Versamark creates its arrayed print head orifice plates with electrolithography. For years, this type of orifice plate worked best with water-based ink. Solvent-based inks tended to erode the extremely tiny orifice holes. That problem was eventually solved with a new design. Solvent-based inks actually run better in some print head designs because solvents keep the orifice clean. A major problem in inkjet technology is keeping the orifices unplugged. Dried ink, a mote of dust, or any other microscopic bit can potentially shut down the print head. A potential problem with UV-curable inks is keeping the intense UV light source from actually curing the ink as it is coming from the print head, thereby killing the whole mechanism.

Suffice to say that the application usually controls the ink type. In the bindery, where UV-coated covers are common, and where the print head my be up to 3/8´´ from the target substrate, aggressive solvents are commonly used with continuous array print heads. Water-based inks also can be used, but not without some form of high-temperature drying to eliminate the water (usually infra-red). In drop-on-demand UV print heads, ink chemistry can vary widely due to a potentially wider variety of substrate applications.

Inkjet printing always has been substrate-challenged due to its water- or solvent-based inks. Water-based inks aren't colorfast, and can run if mailers encounter moisture. Solvent-based inks permitted usage on coated stocks, but imposed some environmental penalties.

Now UV-curable inks can be applied to a wide variety of media, including coated stocks and plastics. The images applied with these inks are also more durable and colorfast, and the print heads are more reliable and trouble-free than ever. This, coupled with its quick turn-around ability, has greatly expanded the universe of potential applications, making inkjet a mandatory application for printers servicing the point-of-purchase graphics market and printing rigid substrates.

New print-head technologies using drop-on-demand technology (see sidebar) have also changed the game substantially. A few key providers—among them HP, Xaar, Spectra and Scitex—supply one core technology, the inkjet print heads themselves. Though there are many integrators of inkjet printing systems, they actually rely on this small corps of suppliers for their systems. Print heads are the heart of any inkjet printing system.

The drop-on-demand print heads use crystals driven to a high-frequency by an electric charge to generate thousands of ink drops per second. Drop-on-demand print heads can be constructed from many types of materials and can work with diverse ink formulations.

Inkjet is also fundamentally a binary technology, so it's typical to find print heads with either 128 jets or 256 jets (1´´ or 2´´ wide). Firms such as Xaar (in the UK) and Spectra, Inc. (NH) design and manufacture the print heads themselves, with various models designed for different applications and operating conditions. Print heads are sold to a diverse lot of OEMs, with project teams from the print head folks working with the OEMs to bring the technology to practical applications.

Greater expertise in mounting large numbers of these print heads and integrating them electronically to print in unison have resulted in inkjet printer/presses up to 16´ across! Better technology for generating more drops allows higher operating speeds with improved print quality. The OEM partners of Xaar and Spectra are many indeed, including Mutoh, SunJet, Imaging Technology International, VUTEk (EFI), Heidelberg, Xennia, Buskro, Kodak Versamark and others. The print head and ink developments also have enabled high-resolution, wide-format printing on metals and optical material.

In commercial and specialty printing, narrow-web flexo presses for labels, tickets, tags, coupons and the like are also using more and more inkjet.

One specific use is for barcoding. Sequenced or unique barcodes are an integral part of labels, coupons and other media, and inkjet easily prints various barcode schemes, varying numbering and embedded data quickly and efficiently. No plates are required and needed data can be pulled from a network server. New UV-curable inks and color capacity are improving the variable-data options. Narrow-web flexo press manufacturers such as Mark Andy are offering digital versions of their web presses, incorporating up to six colors. Players in this market include Jetrion (a company formed by Flint Ink), Domino Amjet and SunJet, formed by Sun Chemical.

Muller Martini has improved upon early commercial web approaches with the introduction of its Concepta web press, shown at Drupa and again at Print 05. While yet to be installed in the U.S., the Concepta marries two powerful concepts: variable offset repeat lengths (through changeable cassettes) and variable imaging. Targeted for the direct mail market, the 20½´´ wide Concepta web tightly integrates Kodak Versamark's wide inkjet imaging head technology.

Concepta can accommodate repeat lengths of 14´´ to 28 1/3´´, and the Versamark print heads can add 300 dpi of black or color variable imaging. Werner Naegli, president of Muller Martini USA, says the press is targeted for production of variable-data direct mail pieces in a one-pass fashion. Concepta adds roll-in, roll-out finishing modules, which allow the press to sheet, slit or fold as required for the final product. Concepta is fast for a hybrid press: up to 1,000 fpm with variable imaging. The conventional offset end has been improved also, with a new ink-train design delivering better color over the press's speed range, and capabilities of coating.

Kodak Versamark is also continuing to penetrate more markets with its series of full 4-color inkjet digital presses. Versamark uses an array of 9´´-wide inkjet heads to produce full process color. It employs separate magenta, cyan, yellow and black print heads that sit in series, printing transparent process color inks.

Earlier versions of this press have been used for some time in the high-volume transactional printing market (credit card statements, utility and telephone bills, etc.) The high speed of Versamark (up to 1,000 fpm) is meant to leapfrog the conventional output of the laser printers used for this work (250 to 400 fpm.) Kodak also believes that adding color (at a competitive price) to statements will prove tempting for credit card billing firms and direct marketers who want to apply it to up-sell recipients of statements.

Kodak Versamark is also pursuing applications which it believes are virgin territory for this technology: low-volume remote printing of daily newspapers in sites frequented by travelers: hotels and airports. Or even longer runs could be done to overcome time and cost constraints for trucking from central print plants.

Kodak's vision is to produce highly targeted newspaper runs of 10,000 to 25,000 closer to the ultimate distribution points. Think of a Versamark VX5000 cranking out various newspapers on demand at a location like O'Hare Airport in Chicago; or for delivery along remote commuter lines connected to central cities. In-line finishing would be a part of such a system.

Even now, a Versamark VX5000 could run about 1,000 40-page newspapers/hour, fully sectioned and ready for distribution. Since Versamark technology employs water-based inks, there are still some technical issues to resolve regarding the practicality of printing on newsprint. But initial tests have found conventional newsprint is proving to work quite well with Kodak's inks, and color quality is reported to be very good.

Planning to stretch the limits of high-speed color inkjet printing is Unigraphica. Based in Ruggell, in the Principality of Liechtenstein, the firm integrates and builds specialized press lines, primarily around narrow webs with variable cut-off capability. The company is at work on a multi-web inkjet-only web line based on the Versamark 5000 4-color print engine.

The concept is to use multiple Versamark 9´´ heads to image multiple webs, merged and delivered in a single collect. A main unit will print CMYK, while the rest of the units would deliver black only. In such a system, a 16-page signature could be produced at 1,000 fpm. Inline saddlestitching could also be an option.

Such a plateless press would have the ability to produce every page with full variability and deliver full-finished publications ready for shipping.

One of the newer inkjet entrants is Agfa, well known as a prepress supplier. Agfa acquired :Dotrix, developer of the SPICE (for Single Pass Inkjet Color Engine), with fixed-array piezo-electric drop-on-demand color print heads up to 24.8´´ wide. The ink is instantly UV-cured, and Agfa's stochastic-screening software driver provides an interpolated resolution of 900 dpi with nine gray-scale levels. The ink is light-fast and provides excellent rub and scratch-resistance.

The SPICE engines run on a servo-motor-driven web transport which can run web cores of from 3´´ to 12´´. :Dotrix can print on an amazing spectrum of substrates, including thin plastics, foils and thick folding carton stock (up to 400 gsm board). :Dotrix made quite a splash at Print 05 and Agfa promises even more innovation at IPEX in England this April. :Dotrix speed tops out at about 100 fpm, but its instant makeready time makes it perfect for short-run label, tag, point-of-purchase and other packaging applications. Agfa is also bundling :Dotrix with its ApogeeX front-end workflow software. The goal is to make :Dotrix another easy-to-use delivery node in the company's comprehensive digital workflow. Future iterations of this press could be capable of printing up to 36´´ across at speeds equivalent to 1,000 A4 (8½×11´´) pages per minute.

Mark Andy has also partnered with Agfa in a DT (Digital Technology) series of 13´´-wide flexo presses. Sun Chemical Digital has entered this field with its FastJet digital press for packaging, shown at Print '05. It uses 20 separate print modules of 24 print heads each, approaching 40´´ in combined width for high-speed delivery of wide materials and rigid substrates.

FastJet is targeted at customized package printing so that retailer-specific content can be included in the package. It can also aid in rapidly developing different package designs envisioned by the marketing folks. Corrugated printing systems of this type can produce work fairly quickly, with outputs that range from 500 sq.ft. up to 3,000 sq.ft. per hour.

Store-specific packaging can also be quickly turned out as actually needed, potentially eliminating overages or shortages of materials. FastJet went from prototype to a production unit last year with an installation at UK printer Jardin Corrugated Cases. Agfa has also installed several :Dotrix presses in the UK. Both companies are making the case that inkjet technology for corrugated and other packaging applications is cost-competitive with conventional offset for short runs.

Other established suppliers of inkjet printing systems have also been busy introducing new products. Domino Amjet and Videojet, long-time sources for the bindery and mailing markets, both showed a number of new advances at Print 05. Domino recently introduced its K-series drop-on-demand UV-curable-ink print heads for the narrow web, mailing and plastic card industries. The K100 and K200 can print 1´´- and 2´´-wide image areas at a resolution up to 520 dpi, with speed depending on substrate's ability to accept the ink.

Videojet has teamed with HP to offer a wide format (2´´ up to 16´´) printing and addressing system for mailers. Videojet's PrintMail WideArray uses HP print heads in 2´´ and 4´´ wide increments to image mail pieces with address and personalization data at up to 600 dpi resolution. While HP inkjet heads are familiar in desktop settings, these industrial-strength HP print heads bypass cartridges, receiving ink in continuous supply from a central ink system in PrintMail (no need to replace cartridges!). PrintMail will gives mailers (and printers who mail) more possibilities with regard to customized logos, graphics, and additional data.

Buskro, Ltd., Toronto, also entered the color market with the Atlas system for mailers and plastic card processors. An iteration of Atlas can print 4-color (including match colors) on mailers and envelopes, giving more options to direct-mail marketers.

At Ipex 2006 (Birmingham, England, April 4-11) expect to see several new developments that will increase the speed and range of inkjet systems. Agfa, Kodak, Domino and Videojet, among others, are expected to unveil wider and faster systems. Domino has already announced it will show a new 4-color, high-resolution DOD inkjet system aimed at commercial applications. Also debuting will be a new secure-printing system for the mailing market.

Xaar will highlight practical real-life applications of its print heads. Xaar's OmniDot platform uses a technique called “Multi-Pulse,” which can run a wide range of gray scales by varying the size of the actual drop.

Xaar will also introduce its HSS hybrid side-shooter advanced piezo DOD technology which will be demonstrated printing on a wide range of substrates. Practical applications include printing CDs, PCB legends, labels (on iTi's new Digital Press), coding, even egg printer from Germany's Honaz.

Spectra partners will be using the company's Apollo and Nova print heads for standard and specialty graphics. Further down the line, developers expect even greater achievements by the next Drupa show, scheduled for May 2008 in Dusseldorf, Germany.

Inkjet will start to take market share away from toner-based printers in transactional printing (credit card, telephone and utility billing). The reason? Speed and lower cost per image. Kodak Versamark can already print text only at close to 1,000 fpm, far faster than laser printing. Transactional marketing departments are also starting to become sold on the use of highlight color in billing statements—a challenge for some dry toner sytems. Tests show highlighting amounts owed speeds payments. Inkjet in package printing will be a sure-fire growth market. Personalization of retail and point-of-purchase graphics will permit printers to quickly produce segmented quantities of high-quality in-store graphics and displays.