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Digital Presses



Inkjet technology intensifies, and finishing equipment takes a higher profile.



Published July 18, 2005
Related Searches: Embossing Narrow web printing UV flexo Digital printing
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Slowly but with strength and confidence, fully digital narrow web printing is moving forward. Every year we publish an update on this technology, which emerged in the mid-1990s, and every year we report that it is here, and getting better, and inching along. It’s not for everyone, but it’s not going away.

Fifteen months ago, at Labelexpo USA 2000 in Chicago, Mark Andy announced that it was at work on a multi-color digital printing unit, in partnership with Barco Graphics, that would someday be mounted inline in a conventional flexographic press. The Digital Label Alliance, through Chromas Technologies, showed its single-color Argio unit mounted on a narrow web press.

These new ideas utilize inkjet technology, which many view as the process that will lend greater speed to digital printing.

Now we come to Labelexpo Europe 2001, held recently in Brussels, and we find that Indigo and Xeikon, the two earliest entries in the field, have expanded their digital capabilities for narrow web. The European audience got its first look at the Argio, and Mark Andy announced that it was nearing completion of its digital printing machine. The St. Louis-based press manufacturer did not show its prototype at the exhibition hall, but rather invited select customers to nearby Ghent, where it was undergoing testing at a Barco facility.

Fully digital presses offer the advantage of elimination of several steps and materials in the print process. Images are digitally manipulated by the prepress department, as they are in the conventional process, but no film is output to an imagesetter, no plates are required, no plate mounting takes place, and no plate cylinders require adjustment on the press.

What happens instead is that the digital image is transferred from the prepress department directly to the computer in the press, which then instructs the machine what to print where. The three processes available today differ in how they achieve the printed result, but the quality is high.

Converters who utilize digital technologies today — there aren’t that many of them — praise the capability of producing short-run work quickly and with excellent results. Narrow web printers who concentrate on longer runs don’t have much use for current digital technology, mainly because the speeds are slower; beyond a certain number of labels the cost curve shows an adverse effect on the profit margin.


Inkjet moves forward
Last year, Mark Andy executives made the decision not to undertake a digital print technology alone, so they joined with Barco, which had developed the Dot Factory, a multi-head inkjet printer utilizing Xaar inkjet technology. The machine they have developed over the past year is a 13" Model 2200 press that includes the Dot Factory unit in the midst of the inline print stations.

The Xaar inkjet technology is basically a color bar with ink cartridges that are temperature controlled. The inks are contained in what is called a SPICE rack, which stands for Single Pass Inkjet Color Engine. The mid-press unit has space for six ink cartridges, meaning the press can work in four-color process with two spot colors, or can utilize Hexachrome six-color process, if desired.

According to Mark Andy President John Eulich, the digital press offers “ease of use, simplicity, little maintenance, and an industrial design. It is integrated with existing narrow web flexographic print stations and finishing equipment. The consumables, such as the inks, are inexpensive, it offers substrate independence, reasonable speed, and the ability to print process quality and spot colors.”

Inkjet is unlike the electrophotography or toner-based printing technologies of Indigo and Xeikon machines. Of the three types of inkjet — continuous, thermal and piezo-electric — the Mark Andy/Barco unit utilizes the latter, as does the DLA’s Argio. But the Xaar system makes use of grayscale technology, which prints at 300 dots per inch (dpi) with eight bits of grayscale. That translates to a print equivalent of approximately 900 dpi of resolution, with eight levels of dot.

The speed of the unit today is 75 to 80 feet per minute. “Technology will advance within a reasonable time to make it feasible to reach higher speeds,” Eulich says, “but we’re not selling that today.”

With a six-color print engine in the midst of a conventional narrow web flexo press, the operator can lay down a coat of white or other color on the substrate prior to the introduction of the digital colors. Post-digital stations can be used for a UV coating or other colors, if desired. Conventional foil stamping or embossing, along with rotary diecutting, follows in the customary progression to the rewind.

“We don’t want the operator to have to do a lot of manipulating,” Eulich says. “We’re against that.”

Inks for the system are UV curable. “We are working with one ink supplier now,” says Eulich, “but others are interested. We have quite a bit of ink development left to do. Mark Andy and Barco will probably not sell inks, but will certify them for use in the press. It is our intent to make ink the only consumable.” Eulich adds that the “number one priority is not to have to coat any materials.”

His references are to competitors. In the early days of the Indigo digital offset press, substrates required the addition of coatings so that the inks would adhere properly. Today coated stocks are readily available. Moreover, inks for the Indigo Omnius web press are available only from Indigo, and the press requires routine replacement of print blankets, which are an additional consumable.

The Chromas Argio 75 SC differs from the Mark Andy/Barco unit in that it is a single-color UV inkjet digital system. The unit prints on a web 7.5" wide, and differs from its competitor in that it can be installed on any existing flexographic press. Mark Andy plans to market its digital unit solely on its own machines.

Argio also utilizes piezo inkjet, ejecting very small drops of UV ink from 4,500 nozzles across the web at 12,000 times per second. Speed, according to the manufacturer, can reach 100 feet per minute. The resolution is 600 dpi across and in the web direction. Available colors are black, blue, green, cyan, magenta, and yellow. Colors are mixable. White is not available, because the pigment loading required is so high that the ink becomes thick and difficult to project through the jets.


Digital offset and toner
Xeikon introduced its dry toner-based digital printing machine in the mid-1990s, and Danish press manufacturer Nilpeter was quick to add the unit to its product line. The press prints at speeds up to 48 feet per minute.

Indigo made a splash in 1995 with the introduction of its Omnius web-fed digital offset printing machine, which utilizes electrically charged inks in an offset style. Since then the product has undergone several modifications, and at Labelexpo in Brussels Indigo introduced its Omnius WebStream 100 press, which prints up to 16 meters (about 53 feet) per minute in four colors. Indigo offers a Model 200 (two engines) and a Model 400 (four engines), which can double and quadruple output, respectively.

The Nilpeter finishing unit designed for the Indigo Omnius
digital press, on display at Labelexpo Europe.

The WebStream 100 is capable of seven-color printing, using the proprietary IndiChrome OnPress and OffPress special colors. Indigo also produces the WebStream 50, a six-color press which it markets for short run label production.

Prestige Label, of Burgaw, NC, recently acquired an Omnius press to handle its short run work. “We were finding short run work that caused us to curse every time we put it on a flexo press,” says President Elisha Tropper. This is really short run work, like 1000 labels from mom-and-pop companies. We found ourselves providing really short runs for customers and losing money, but doing it to keep the rest of the business.”

Prestige bought the digital press with “a customer base ready to cover it, not fully but to get us a lot of the way there. That made the transition smoother,” says Tropper. “We can look into new markets more easily now. We’re not looking for runs of 100,000 to five million labels, but rather for runs up to 5,000 labels.”


Finished
The basic print engines do not come with post-press finishing equipment. Converters who acquire Indigo and Xeikon/Nilpeter presses have had to make use of offline equipment. Recently, companies such as Omega Converting Systems and Rotoflex have designed post-press units for digital presses that can be installed inline.

Now, Indigo has announced an OEM agreement with Nilpeter for production of a finishing line. It includes an interface unit with web tension and web guidance controls, digitally or conventionally controlled diecutting and waste rewind, a laminating unit for cold and UV lamination and super varnishing, and a UV flexo varnishing unit with cold UV curing.

Xeikon has introduced LabelSprint, a compact finishing unit based on the Xeikon UCOAT system. It operates in-line at full press speeds, offering roll-to-roll finished output, or it can be used for near-line finishing. It has a modular design that can be configured for various options including UV coating, rotary die cutting, slitting and stripping.



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