Computer-to-plate: narrow web converters are moving swiftly to adopt this new technology.

Until the doors opened on Drupa 1995, the giant print exhibition in Dusseldorf, Germany, photopolymer flexo printing plates had been manufactured conventionally, using light rays as the source for exposing the image on the plate material. That all changed at Drupa when DuPont unveiled its digital flexo plate material. DuPont teamed up with Barco Graphics (now Esko Graphics), to construct a laser powered digital plate engraver.

Interest was high, but so was the price. The machines were big, solid, heavy; powerful and accurate, and produced plates with a consistency that the conventional process could not duplicate. The early machines cost in excess of $300,000.

Over the next few years, the wide web printers expressed interest in computer-to-plate technology (CTP), as did trade shops that produced plates for smaller printers. Narrow web converters, however, waited on the sidelines for two thins to happen: the production of smaller digital plate processors, and a drop in price.

That day, it appears, has arrived. Industry sources say that the penetration of digital plate processors into trade shops is well under way, and so are sales of the processors to narrow web tag and label manufacturers. The machines are smaller now, and prices for them have dropped to a range of $130,000 to $150,000.

No more film

Inside a digital plate engraver is a drum and a laser generator which burns the image onto the plate. The work begins in the prepress department, where it always does, with creation of the image on the computer. One significant benefit to the digital process is that the analog portion -- the production and use of film -- is eliminated. The image is sent electronically to the plate processor and produced thereon directly.

With one exception, the balance of the process is the same as with conventional plates. Solvent wash systems are employed, and the plates are dried.

Marketers of the systems, as well as those using the devices, report two significant benefits: a better quality product, and a process that leaves no room for human error. "With digital plate processing you get a better dot formation, as well as repeatability of the process," says Mark Vanover, marketing director of packaging at Creo, Bedford, MA. Creo produces a processor called ThermoFlex 2630 for the narrow web market.

TRISoft Graphics Inc., a prepress shop in Fullerton, CA, installed a ThermoFlex in July. President Tristan Zafra says that the elimination of film and chemicals in the plate making process has begun to save the company money, as well as reducing production challenges.

"A completely digital workflow makes everyone's life a lot easier," says Zafra. "We wanted to produce better quality plates, and at the same time eliminate the variable problems of platemaking -- chemicals, film, film calibration, air bubbles between film and plates during exposure, and oxygen depletion. With CTP we achieve quality that we can never get with traditional plate making, and our converters are printing better than ever."

Narrow web interest grows

"The first 30 installations in North America were trade shops, with the exception of a couple of big wide web internals," says Ray Bodwell, DuPont Cyrel digital marketing manager, Wilmington, DE. "Over the past six to nine months the activity has picked up, particularly in the narrow web segment. CTP installations are taking place in noticeably visible label companies. It's not the exclusive domain of wide web any more," he says.

Bodwell says that 110 CTP machines are in place in North America today, "and at least 25 to 30 of them are at narrow web converters.

"A tag and label converter doesn't have to be well-heeled any more to get into digital plate production. Esko Graphics and Creo have units in the $150,000 range and below," Bodwell adds. (Creo's basic unit starts at $129,000, according to Vanover.) "But it's important to remember the savings that result from the investment. You eliminate the film and the processing. When it's time to update your plate processing equipment, there is a significant cost benefit once you get past the initial capital cost," he says.

Creo's ThermoFlex 2630 processes plates that can be up to 26"x30" in size. "The processor can handle qualified media from all major vendors," says Vanover. "There is no favoritism to any media vendor."

"What sets the ThermoFlex apart from the others is that it has an ease of use and operator friendliness," Vanover notes. "Because we spin the drum at very slow revolutions, you only have to tape the plate on the lead edge and the trail edge. The entire drum has vacuum to it. With the slow revolutions you don't have to mask off what is still exposed. Because flexo media is very expensive, you only want to expose what is needed. Here you don't have to cover the other vacuum channels, as in other machines.

"Another advantage is that even if you have a small plate, the drum is dynamically balanced. With others, even if you have a 14" square plate, you'd have to have a full plate length and cover the other vacuum channels.

"The technology has been around for several years," Vanover notes, "but it has been a slow adoption process. We're starting to see an increase in people adopting digital flexo plate making. We now have about 100 installations -- narrow, mid and wide web -- worldwide."

Science yes, art no

Among the advantages CTP offers users is ease of use and repeatability. "All the parameters are stored digitally," says Vanover. "Runs are getting shorter, and though the core packaging of a product doesn't change over time, the product tie-ins change often. Digital allows you to continue with shorter runs with the same quality from day one to a month later."

The learning curve for plate equipment operators is not at all steep, the experts say. Bodwell of DuPont paid a visit to a West Coast converting company to watch a CTP unit being run by a woman who spoke no English and who hadn't known what a flexo plate was two months ago. She had been given the parameters by her boss, the prepress chief, who took off for a business trip and left her in charge. "She was trained by the prepress guy in a week. She has the QC targets, and is getting it done.

"In our view, this is a bulletproof workflow," Bodwell says. "It has gotten flexo to where the operation is consistent and repeatable, the way offset has become over the years. The magic is, for the most part, out of the plate setting area. The art is in the front end, the prepress and imaging. Plate setting should be a science: Once the file's done, it should be bulletproof."

Bodwell maintains that the image produced by a digital plate setter is better than that produced by conventional light exposure systems. "The highest quality in flexography is in the tag and label segment," he says. "This type of equipment, and the digital plates, can hold a much finer tonal range. It looks different, and is purely chemical. When you work with digital plates, you no longer have to draw a vacuum in the processing. The dots form differently, and they print with much less gain and much more consistency. Vignettes -- fading to an actual zero -- is very do-able."

Digital plates, which are offered by several suppliers, are different than conventional photopolymer plates. "A highlight dot on a conventional plate looks like a cone lopped off on top," says Brad Taylor, research associate for DuPont Imaging Technologies. 'With digital its a small rounded tip. The size of the dot is noticeably smaller than a dot on film, he adds. "There's an automatic built-in cutback. You don't have to do it in electronic prepress or minimize the tonal levels in an eight-bit file format at prepress."

Fast times

Some converters are taking advantage of the DuPont Fast plate technology that was introduced in 2000. The process is dry from start to finish; gone are the solvents used to wash the unwanted photopolymer from the image on the plate.

The first DuPont Cyrel Fast plates were made for conventional exposure technology After exposure, the thermal dry photopolymer flexo plate is subjected to heat, allowing the unexposed areas of the plate to soften with the heat. The molten polymer is then absorbed by the developer roll fabric inside the processing unit. Now, DuPont has developed digital plates for use in the Fast processor.

"Most Fast installations are computer-to-plate," says Taylor. "We sell them as a system, by the square inch of finished plate. We put the developer into the plant, and we give the converter the developer rolls and take them away when they're used. We give them the plate material. The user is charged for the square inches of material that goes to the press room. That reduces the up-front investment."

"Fast is the perfect companion for CTP," adds Bodwell. "It has one-hour access time. It eliminates solvents, and has no real environmental impact, because there is no developer to dispose of."

RELATED ARTICLE: Alternative to CTP push analog to the limit

CTP is not for everyone. Some converters will stick with their tried-and-true conventional systems as long as they have to. There are, however, alternatives to the merely conventional. Companies such as Olec and Cortron have taken flexo plate exposure a long way from simple exposure to the light source.

Cortron, in Minneapolis, produces a system called eXact, which tightly controls the angle of light that hits the plate. According to Marc Fioravanti, VP of sales and marketing, "the system uses a single light source in conjunction with a mega-faceted reflector that collimates light to the same 30 degrees of CTP resulting in crisper dots and deeper reverses. A digital integrator controls the consistency from plate to plate over the life of the light source. Other features such as liquid cooling of the light and the retro reflector eliminate any heat issues and falloff. "We see eXact as a viable alternative for those who aren't ready to convert to CTP," says Fioravanti. "Our tests show that plates exposed with eXact show significantly less dot gain than any other analog plates and rival those imaged by a CTP device. There is marked improvement in the final printed product."

"The digital flexo plate has a mask layer, sensitive to the laser light, on top of its surface. After imaging, the mask takes the function of the traditional film negative. Through the integration of the image carrier, a digital flexo plate has sharper image definition and steeper relief shoulders than conventional plates produced with film. Image deterioration by UV light absorption and scattering in the traditional contacting through vacuum sheet and film is totally eliminated." -- Esko Graphics