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DIGITAL PRINTING: DIGITAL PRESS UPDATE

Feb 1, 1999 12:00 AM


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In 1998, the digital printing world refined its processes and made significant production operating cost reductions, as well as introduced new equipment and technology. This trend is expected to accelerate as the industry moves toward the year 2000.

Digital printing progress is being made in both the fixed-imaging on-press platemaking approach, as well as the direct-to-paper technology (plateless variable imaging).

"I can do it better, faster and cheaper than you can," was the battle cry of Indigo, Xeikon, IBM, Xerox and Agfa, as the variable imaging digital color printing press pioneers intensified their maneuvering for market share. An indicator of variable digital color printing's expanding reach into the traditional print market is the press dealerships established by Pitman (which sells the Xeikon-engine-based Xerox products) and PrimeSource (selling the Xeikon-branded equipment).

Indigo, Xeikon and its cohorts all introduced new models or noticeable modifications of existing machines, each finding a way to claim better and less expensive production performance. They all are moving in the right direction in that the cost of digital variable printing has declined significantly. And a decline in cost is enlarging the market.

Both Indigo and Xeikon have set their sights on the packaging and label markets with equipment model variations specifically designed to meet these markets. Xeikon recently announced the availability of a fifth color unit and a white toner for its DCP/32S and DCP/50S models. Indigo targets flexible packaging with its Omnius roll-to-roll digital web press.

Xeikon also is pursuing the label market in partnership with Nilpeter, a high-end label press supplier. And a consortium led by Didde Graphic Systems also has a digital label press under development, but has not announced any details or projected a date of introduction.

With a growing realization that customization, individualization and versioning are the killer "apps" markets for digital printing, a bevy of personalization software tools came to market during 1998, with more and more sophisticated software drivers expected this year. (For more on personalization software, see the article on page 40).

Xeikon's recently announced strategic partnership with Varis is expected to result in sophisticated full-color digital printing software becoming available early this year. Indigo has announced two new press configurations, one at each end of the cost and performance spectrum. Now available is the economy E-Print Pro, priced at $249,000. The high-end seven-color UltraStream, which Indigo rates at 2,000 single-sided, four-color 11.7 x 17.2-inch sheets per hour, is expected to be commercially available in the second half of 1999. Pricing has not been announced, but pundits estimate it will be in the $500,000+ range. The $400,000 six-color TurboStream is expected to remain in the Indigo product line.

Of additional interest is Indigo's recent announcement of a strategic technical alliance with Hewlett Packard. This relationship was established to explore future products and markets, giving rise to speculation regarding HP's digital output product directions.

As the two direct-to-paper competitors move forward, two new candidates emerged in September at Ipex in England.

Xaar, a small UK inkjet development group, and Elsorsy, based on Quebec, both appeared on the scene. Both technologies are in the development stage, but both technologies showed imperfect but highly promising samples. Either company could upset the current variable imaging full-color printing press market.

In the first public demonstration of a press based on its electrocoagulation technology, Elcorsy printed four-color samples on a single-sided five-unit press configured for four over one production. (The second side printing was not demonstrated.) Printing at 200 dpi with a variable size dot at 200 fpm, the new technology proved that it could print commercially acceptable pictures. Type, which was not printed during demonstrations, appears to be marginally acceptable, but noticeably below normal printing industry standards.

Elcorsy expects that by Drupa 2000, when the press will be commercially available, resolution will be up to 400 dpi at a speed of 400 fpm. At that resolution, particularly with the capability to use variable dot sizes, image quality should improve and type be more than acceptable.

While the Elcorsy Ipex demonstration was impressive, of particularly interest is the electrocoagulation technology, which is just at the beginning of a development cycle. Toray Ink is a major investor in Elcorsy and should help to nurture the technology to its full potential. (For more on electrocoagulation, see accompanying sidebar on page 50.)

Less flashy was the Xaar inkjet demonstrations of label and folding carton printing. Completely variable four-color labels were printed on a 2.5-inch-wide concept device running at 20 inches per second. The folding carton demonstration was done with four printheads (one each for CMYK) moving on an XY plotter. Print quality from both demos was generally thought to be commercially acceptable.

Xaar is a developer of high-performance piezoelectric inkjet printing heads, which are licensed to other companies. Xaar also has developed an oil-based pigmented ink currently manufactured in the UK by Zeneca.

Although Xaar's plans have not been revealed, the firm has indicated that it could produce a full four-color digital printing press by Drupa 2000, perhaps running at 100+ pages per minute.

Still in the development woodwork is the Scitex Digital Printing four-color inkjet press shown in a technology demonstration at Drupa 95 and slated for commercial introduction at Drupa 2000.

Also looming on the horizon is the introduction of the Heidelberg-Kodak NexPress, which is expected to be a full-color, completely variable, high-speed digital press. Little information is available, but rumbles indicate that a workforce numbered in the hundreds is working on the press. The technology is described as thermal-electrostatic--whatever that may be.

At the same time as these high-end developments, laser and inkjet printers have dropped in cost, allowing low volume customized and personalized printing on these desktop devices.

High-speed color copiers are beginning to look more like low-end variable imaging digital printing presses. Xerox has split its DocuColor 40 copier/printer line into two basic versions--the 40 CP and the 40PRO. The 40CP is a network connected copier/ printer equipped with a digital controlled from EFI. It's suitable for walk-up copying as well as low-volume network printing. The 40PRO is intended for sophisticated color document production, which emphasizes speed and color quality.

In another approach, T/R Systems continues to expand its MicroPress cluster system options. T/R now can assemble a variety of systems that can produce impressive work, mixing black-and-white and color pages as required. The installed base is beginning to approach 1,000 systems.

As variable imaging presses proliferate, Heidelberg is expanding on its on-press, direct-to-plate, fixed imaging directions. At Ipex in September, the press manufacturer introduced a four-page Speedmaster 74-DI and an improved version of the Quickmaster DI.

The Speedmaster 74-DI drew standing room only crowds at Ipex and considerable interest at Graph Expo. Observers acknowledged that the highly automated machine was an improvement over previous DI press models and that it is capable of producing high-quality work.

The question remains, however, is it a good investment? At a capital investment cost in the range of 18 percent to 20 percent more than a standard Seedmaster 74, the new direct imaging press is viewed as "pricey" by some.

Noting that the on-press direct imaging concept provides printers with many advantages, Ron Kendig, Heidelberg's marketing director/direct imaging, observes that in the growing world of on-demand printing, the DI clearly has an economic advantage when running time is the same or shorter than off-press platemaking time. As a new press now in beta, the exact ROI is uncertain. A simulation cost analysis model is being developed that will help to pinpoint the economic window for the 74-DI press, Kendig says.

Characterized as a fast makeready, short-run press, the 74-DI's job changeover time is between eight and 11 minutes. Of this total changeover time, three to four minutes is used for plate imaging, which is done simultaneously on each printing unit. The balance of the time is used for plate removal, wash-up, ink setting, side guide alignment and press startup--all functions required on both digital and conventional presses.

Kendig points out that the only significant makeready time differential between a conventional press and the 74-DI is the actual on-press plate imaging time, which is accomplished unattended. Ink fountain keys on direct-to-plate digital presses are set automatically from an analysis of the pixelized prepress data used to image plates. Automatic ink key setting is an important time-reducing factor built in DI presses.

Like its conventional counterpart, the Speedmaster 74-DI is a 20 x 29-inch four-page format press with a maximum speed of 15,000 sheets per hour. Although processless Presstek Pearl Gold thermal plates were used in the demonstrations, the Presstek imaging heads used in the earlier DI presses have been replaced with Creo thermal imaging heads.

Unlike previous DI models, which use waterless technology, the SM 74-DI prints with fountain solution. It can print with off-press-made plates, as well as in the on-press direct-imaging mode. The press is available as a four-, five- or six-color machine with inline coating and perfecting as options.

The first SM 74-DI will make its U.S. debut in May. After its initial shakedown, the first machine should to go to Watt-Peterson in Minneapolis for final U.S. preproduction testing.

With more than 800 systems in operation worldwide, the Heidelberg Quickmaster-DI 46-4 has been improved, reducing plate imaging time to four minutes. An increase in the ink zones from eight to 12 and an improvement in ink blade fountain technology contributes to higher quality production. The QM DI 46-4 Plus has a fully automatic lubrication system and direct access to the individual ink zones from the operating panel. The Quickmaster Plus is expected to be available in the U.S. during the second quarter of 1999.

Screen, the Japanese-based prepress supplier, debuted its entry into the fixed image digital press business with an operating demonstration of its four-color TruePress at Ipex. Loaded with software features, the press uses conventional CYMK process and spot-color inks as well as a continuous feed dampening system. Plates are flexible polyester, such as the Mitsubishi Silver Digiplate.

Screen's entry into the digital press race is completing beta site testing in Japan and is expected to be available in the U.S. during the second quarter of 1999. The TruePress is priced at $375,000.

Karat Digital Press, the joint venture of Scitex and KBA, is poised for commercial U.S. market entry before the end of the year. The 74 Karat, a four-up, sheet-fed offset 20.5 x 29-inch press, is currently beta testing in Belgium. U.S. preproduction testing for the press, which is priced at just under $1 million, is expected to be under way by this summer.

Although the Karat press has been undergoing continuous refinement since its public introduction two years ago, its self-calibrating, keyless gravure-like inking system and unusual split plate/central impression cylinder arrangement, remains the same. Major advances have been made in reducing the makeready time for the 74 Karat, as well as significant print quality improvements, reports Doug Clott, North American sales and marketing director. One key to improvement is changing cleaning methodology used to ready the waterless-processless Presstek Pearl Dry plates for printing.

Tim Hackney, national sales manager for Omni-Adast, notes that it has been slow going to convince printers that a DI press is viable in the half-size format and for more than short runs. The Omni-Adast DI series uses Presstek laser diode imaging technology and Pearl Dry thermal plates. Since the original 19 x 26-inch introduction, an automatic plate cleaner has been added to the press to assist in removing particle debris caused by the laser ablation platemaking process. More recently, Omni-Adast has added an aqueous coating tower to its four- and five-color configurations--two of the firm's seven DI installations use this configuration.

An Omni-Adast five-color, including the server, RIP, press computer and temperature control system, sells for just under $1 million.

A different on-press imaging approach is being taken by MAN Roland and Goss, both of which have erasable cylinder press concepts on the drawing board. Although the concepts are radically different, both create an image on the press cylinder without using a disposable plate. After a press run, the cylinder is erased, and the same cylinder is re-imaged for the next run. If the erasing and re-imaging can be done quickly enough, this concept appears to be an economically viable alternative for producing versioned publications now created in the bindery.

The Goss digitally imaged reusable cylinder approach is one component of the firm's Advanced Digital Offset Printing Technologies Concept Press (ADOPT/CP). The concept also incorporates single fluid lithography, gapless image and blanket cylinders, and shaftless/gearless individual cylinder drives.

MAN Roland's DICO Web--Direct Image Change Over Web Press--is being developed in both gravure and offset versions. First demonstrated at Drupa '95, Martin Lange, marketing member of MAN's board of directors, indicates that the development is still on the drawing boards and headed for Drupa 2000.

Digital press development is proceeding at an accelerating pace for both fixed image and fully variable imaging presses. Fixed image developments are being led by direct-to-platemaking on-press technologies. Full-color, 100 percent variable capability presses are entering the production mainstream as their operating costs decline, while output quality improves and the presses become wider and faster.

As printers look at re-equipping their plants for the 21st century, difficult choices between conventional and an emerging digital press must be made. A mistake can put a firm's survival at risk, but failure to re-equip to meet client expectations will almost certainly be fatal. Knowing when to harness available pressroom technology has become printing management's most difficult task.

The Screen TruePress is a fixed-image digital press that debuted at Ipex in 1998. As shown in the diagram, the first plate cylinder is positioned under the imaging head. The flexible polyester plate material is fed from a cassette onto the plate cylinder. In a split cylinder arrangement, the plate is imaged for two colors, in this case, magenta and black.

After exposure, the plate is processed in a developing apparatus that is located directly underneath the plate cylinder position. After processing, the first plate cylinder is moved down into the printing position where it will make contact with the first blanket cylinder.

This process is repeated by moving the second plate cylinder up into the imaging position where, after plating, an exposure is made (cyan and yellow). After processing, this cylinder is returned to the printing position where it comes into contact with the second blanket cylinder.

Ink key settings are calculated directly from the prepress digital data. After ink keys are set and the plate is inked, the images are transferred to the two blanket cylinders. A central impression cylinder is used in the transfer of 4/0 images to paper. An optional perfector unit is available for 2/2 work. The press is rated at 4,000 iph for four-color or two-sided and at 8,000 iph for one-sided or two-color work.

Plate loading and unloading, imaging, developing, fixing, ink key setting, blanket cleaning and printing pressure adjustment are done automatically without operator intervention. A controller enables job scheduling, print spooling, two-page step-and-repeat, soft proofing of post-RIP data, parallel processing for data transfer, RIPing and remote console operation.

Elcography is a new continuous-tone, variable imaging technology based on the electrocoagulation of a conductive polymeric water-based ink. The ink uses standard offset pigments as colorants. The process is patented by Quebec-based Elcorsy Technology, Inc.

The differentiating technology is the electrocoagulation of the special inks by computer-controlled ultra-short electrical pulses that are transmitted through the ink to create three-dimensional, variable-size dots. These dots diffuse to form a continuous-tone imaging area. Each dot is generated independently by hair-sized wire electrodes (cathodes) that trigger micro-chemical reactions on a positive electrode or anode.

The positive electrode is a metallic rotating imaging cylinder that carries the ink. The ink is imaged on the cylinder and then transferred to paper or other substrates. The print head consists of thousands of tiny wires that function as negative electrodes and are arranged in rows perpendicular to the printing cylinder. Discreet low-voltage electric pulses are fed through the ink in time intervals that vary from 50 nanoseconds to four microseconds. This pulse time difference makes it possible to generate images with dots that have an extremely precise variation in size and thickness to represent a continuous-tone image.

The electric pulses pass through the ink to the imaging cylinder where a micro-chemical reaction takes place at the cylinder surface by electrolysis. This micro-chemical reaction results in the release of ferric ions that, in effect, grab and coagulate the ink on the cylinder in an image pattern controlled by the computer and in accordance with the signal time amplitude. As soon as the electric signal is in an "off" position, the micro-chemical reaction stops instantly without any tail-off.

At this point in the process, the image exists in the form of coagulated ink, which is somewhat gelatin-like, drier than the uncoagulated ink, and grafted or attached to the imaging cylinder. The non-image area exists as fluid uncoagulated ink. The uncoagulated ink is removed from the cylinder by a rubber squeegee in a doctoring-type action. The remaining image is then transferred by high pressure, without heat, to a substrate and dries by evaporation.

The fact that elcography is a continuous-tone, fully variable imaging process makes it totally different from other printing processes. In some respects the process is similar to variable cell size gravure, which lays down varying ink film thicknesses and uses a doctor blade to remove excess ink from the imaging cylinder.

As a continuous-tone process there is no conventional "rosette" pattern. Moire and screen angle issues disappear. Dot gain is not an issue. Special halftone screening algorithms are not needed. Elcography images can be created by any front-end system that can produce bit-mapped output.

The high-pressure cold transfer of ink from the image cylinder to a substrate allows the system to handle a broad range of printable papers, at least theoretically.

When embodied in a web press, the elcography technology requires a seven step process in each non-perfecting unit. Like conventional offset presses, each color to be printed requires a separate unit. Also, like any conventional press, it appears that normal web handling and unit-to-unit issues and requirements prevail.

The process steps used in the Elcorsy Model 200 technology demonstration press are as follows:

* Conditioning. Starting with a clean imaging cylinder, the first step is the application of an ultra thin layer of oil whose primary function is to help the ink transfer to the substrate.

* Ink injection. The cylinder is inked by injection from parallel nozzles. The ink is carried by the cylinder rotation to fill the gap between the printhead and the imaging cylinder.

*Writing or imaging. Based on computer-controlled buffer-stored data, electronic pulses are sent from the cathodes through the ink to the imaging cylinder.

*Coagulation. Because the ink is conductive, it transmits the electric signals sent by the printhead to the imaging cylinder. At the imaging cylinder, an electrolysis action generates chlorine ions. The chlorine breaks down the passive surface of the stainless steel cylinder into very active trivalent ferric ions. When the ferric ions are released at the surface of the cylinder, they cause cross-linking and coagulation of the polymers in the ink. The electrocoagulation activity can be likened to a fast inking micro-valve that is constantly opened and closed in different time intervals to obtain dots of variable thickness. Ink now resides on the cylinder in coagulated form for the image area and in fluid non-coagulated form for the non-image area.

* Revealing. In a doctor blade-like action, the uncoagulated ink in the non-image area is squeegeed off the imaging cylinder revealing the coagulated image, which represents dots on the cylinder. The ink surplus is removed by side gutters and returned to the ink injection container.

*Transfer. The coagulated ink is transferred from the image cylinder to the substrate by high pressure exerted by the transfer cylinder. The image dries by evaporation.

*Cleaning. The printing cycle is completed by the removal of any non-transferred ink and the conditioning oil applied in the first step. The imaging cylinder is cleaned with brushes, soap and high-pressure water jets. The water is returned to filtering tanks and constantly re-circulated.

The cylinder and seven-step process arrangement permits multiple steps to take place simultaneously. While the first image is being transferred, a new image is being written on the printhead. Each image written onto the cylinder can be totally different from the previous image. Elcorsy claims that color, density and contrast correction can be made on the fly.