In-the-Round Plate Imaging

VALIDATION OF AN idea comes with commitment. Creo (Bedford, Mass.) and Esko-Graphics (Vandalia, Ohio) are only two of the companies that demonstrated their commitment to packaging and flexo digital plating at CMM in April. Both announced enhancements to their flexo CTP devices. With several hundred machines out there now, and the assumption that CTP technology is here to stay, each company has focused on speed, automation, and improved sleeve, or in-the-round, imaging capabilities.

I had the opportunity to get a close-up as Creo unveiled its next generation ThermoFlex. The result of more than 18 months of engineering, the machine design seems to consider every move an operator would make in several distinct digital imaging scenarios: film, sheet photopolymer, rotary letterpress plates, and variable repeat flexo sleeves or imaging in-the-round.

The new ThermoFlex, which according Flexo Product Manager Bob Dalton began shipping the same time as the show, has an integral load/unload table for flat film and plates, eliminates the need for masking; and has a slick semi-automatic changeover system for switching from sheet mode to sleeve mode.

As it was demonstrated to me in Chicago, the machine de-couples and stores the sheet-imaging drum on board in about three minutes. It eliminates some of the capital expense here for new entrants because it doesn't require any heavy lifting equipment or an overhead gantry system.

Creo has thought out the entire in-the-round (ITR) workflow and shows the ThermoFlex in a production hub of auxiliary equipment, which includes a pre-mounter, cutting table, and pedestal loader. Sleeve mandrels, which consist of a universal arbor and multiple lightweight mandrel shells of different repeat sizes, are installed in the machine with the aid of an inexpensive lift. Successive sleeves are then loaded/unloaded onto the cantilevered mandrels directly in the machine. When the repeat size changes, a new mandrel shell can be installed in just a few minutes.

Trade shops and printers who've put in a digital flexo plating system tend to convert a steady increase of their work over to the digital side—probably 50 percent or more. However, by current estimates, 80 percent of flexo plates are still produced conventionally. That's a big enough market potential to justify the ongoing machine and material improvements that the suppliers are delivering.

The market for ITR imaging is still pretty speculative, however. One thing moving adoption along is the prevalence of the gearless CI and inline presses that require sleeves or are sleeve compatible. "Sleeve systems reduce machine downtime, and at $300-$400 an hour that's significant," comments Tom Bass, national flexo product manager for Xymid, LLC (Chester, Va.). "When you're finished running one job, you can have the next set of sleeves all ready and waiting. If the inks are more or less the same, you're swapping out the sleeves press-side in a half-hour versus a couple of hours to change over a set of print cylinders. Depending on how many times a day you change over your press, it can be a substantial savings."

Bass comments that sleeves have other inherent advantages. Like savings on sticky back. Plus, since the plates are stored on the sleeve, printers don't run the risk of stretching or ripping them when they're removed from print cylinders.

Xymid makes a Mylar spiral wound plate sleeve with a heat-activated adhesive to form a composite in wall thicknesses from 10 to 120 mil. "Sleeves also provide the flexibility to cut down on inventory and tooling cost," says Bass. "For one thing, sleeves in varying thicknesses can be used to "build up" several desired repeat lengths for the same set of cylinders. Also, instead of having to buy 16 cylinders per repeat on an eight-color press, the printer can buy just nine—eight to fill the press and one to use as a base for mounting plates on a second set of sleeves."

And where does Bass see converters making the step from sleeves mounted with pre-imaged flat plates to sleeves imaged in-the-round? "The flexo industry would like to surpass technologies employed in offset and gravure. So there's a natural interest in digital imaging and ITR. But along with the interest comes the capital expenses. The converters with intense quality demands (high line screens, combination process work with halftones and vignettes) are the companies looking at digital imaging."

In-the-round imaging is a convergence of digital flexo technology and sleeve technology, and could only seem so viable in this exact place and time. (All of you who predicted it can soon say: I knew it!) It's been out there, but its application has been limited mostly to "seamless" printing of infinite repeats or nested designs (wallpaper, gift-wrap, etc.). OEC Graphics (Oshkosh, Wis.) pioneered the seamless process and has had the only significant market presence.

With sleeves beginning to dominate in the pressrooms (and with ITR being in practical use already in Europe) we can start to see advantages of using ITR for non-seamless applications, too. Explains Tom Cassano, packaging product manager for MacDermid (Atlanta, Ga.): "Imaging the photopolymer while it is on the carrier sleeve [ITR] is a process very forgiving of plate mounting errors. That's important today because as we push flexo to its quality limits, even a 20-mil skew can create hours of waste and downtime. When we put an ITR sleeve in the print deck, all we have to worry about is accurate side-to-side and front-to-back register."

MacDermid, who supplies raw photopolymer for seamless processes and is one of the two largest players in the flexo plate market, is keenly interested in ITR. The company manufactures two ITR processors and is active with other digital plating and ITR initiatives. "From the supplier's perspective," says Cassano, "the key to making ITR more attractive is to make a photopolymer sleeve that is easy to acquire, and inexpensive to the point where it could be disposable after one or two press runs."

New ideas on the horizon

One project on the table is the Continuous in the Round Uniform Sleeve (CITRUS). CITRUS is a "thin sleeve" with polymer directly applied to create an imaging blank that is then blown onto a cushioned bridge sleeve before imaging and processing completely in the round.

Other implementations are already on the market or are close to being ready for commercialization. I think that means we can expect to see ITR heating up soon—if not for the immediate payback in the pressroom, then for the very provocative impact on flexo reproduction quality.

As Cassano puts it: "...Flexo has made a huge dent in domains exclusive to offset. Now that we've taken the technology another step forward, and are looking at ITR—digital and continuous—we've got a good conduit for stealing business away from gravure, too."

-By Terri McConnell, PrePress Editor