Coating Hybrid-UV

From downtown Chicago, it can take more than 60 minutes in rush-hour traffic to get to Zoom Graphics USA in the far-south suburb of Oak Forest, IL. But big-city designers don't mind the drive when they're approving press sheets flooded with reticulated coating that literally rises above the paper. Formerly known as Metro Litho, Zoom was acquired and renamed in 2003 by Sandip Mehta, CEO. The 54,000-sq.ft. plant, which has grown to 45 employees, had sales of more than $7.5 million in 2006.

The pressroom features two Ryobi presses purchased from xpedx Printing Technologies in 2005: a 4-color, 14×20" 524GX model dedicated to printing with ultraviolet (UV) inks and a seven-unit, 23×29½" 756 hybrid-UV model. In addition to inline UV, both presses have aqueous coating capabilities. The printing units on the seven-unit 756 (6-color plus coating unit) feature double-diameter impression cylinders and transfer drums with large curvature ratios.

While Zoom prints jobs requiring anywhere from 500 to 50,000 sheets, the three-quarter-size machine is ideally suited for the short-run, multi-color work that comprises the company's UV niche. The hybrid-compatible press runs 24 hours a day, 6½ days a week (until 10 p.m. on Sundays).

More than 80% of what it prints on the 756 press is hybrid-UV with various coating techniques, some of which have become popular among Chicago's design community. In addition to its own customers, the firm's masterful expertise has earned it outsourced work from other printers in the region.

“Spot UV dull [varnish] with reticulation is a big hit,” says Al Burk, plant supervisor who served 23 years at Metro Litho. “But it's a learning experience.” Ryobi calls the process “chemical embossing.”

A sample sequence through which the raised, thermographic-like coating can be achieved: After 4-color printing with hybrid-UV inks from Joules Angstrom, the metal plate in the fifth printing unit applies Hybrid UV Effect Varnish from Environmental Specialties, which is cured via Prime UV Diamond Series lamps in the interdeck unit over the impression cylinder.

Then the entire sheet is coated with Sun Chemical's Reticulating UV Coat, which is cured by the UV unit in the delivery. During this process, a chemical reaction takes place, resulting in the distinct division of the dull, leathery coating and the smooth-grain gloss.

Prime's water-cooled UV systems are custom-engineered for Ryobi presses. The 756 at Zoom has six curing lamps—three are interdeck that, like cartridges, can be snapped in and out to any position in 10 to 15 minutes. (Corresponding plugs in the power box also are snapped into place.) Nine positions are possible; five can be used at a time. The printer runs a limited amount of work as straight UV using five lamps and no coating.

The UV lamps are placed safely within the guts of the press. They feature quartz plates that guard against paper going into the lamps during misfeed—and against shattered glass getting into the press.

Next to the press console are Smart System controls that don't let Zoom go on impression until UV lamps are powered up enough to cure inks. Together with remote diagnostics, these controls, which also track lamp hours and location, are more commonly seen on web presses but are moving into the sheetfed arena, first with Ryobi.

For the past two years, Zoom has been using Böttcher Systems mixed-mode (hybrid-UV) Chameleon roller coverings, which won a GATF Intertech Technology Award in 2005. The hybrid press also features a Harris & Bruno flexo blanket flood coating system delivering coating to an anilox chamber and, from there, to the blanket. It can switch between UV and a aqueous coating with the push of a button—the 15-minute automated changeover cycle pulls out the coating from the coaters, refloods and evacuates them, then fills them. Wash-up fluid is 50/50 UV wash with some alcohol.

The H&B chamber coaters have three different mesh anilox drums to coat distinct surfaces, depending on the desired effect. For satin finish, for example, a different liquid coating is used. The mesh types have varying degrees of coarseness to apply different coating viscosities. “The nine [mesh] we use for straight UV,” says Alberts. “The 14 works great for contrasting between dull varnish, and the 16 [the most coarse] we use for chemical embossing.” This roller laser-burns at the equivalent of a 175 line screen for the super-bumpy technique.

Jobs using conventional inks and aqueous coating account for about 10% of the work Zoom prints on the Ryobi 756. The press's Prime IR Action Dryer System combines directional hot-air knives and three infrared (IR) lamps in the extended delivery.

As a sheet exits the coating unit, it passes under the first set of hot-air knives, which force out moisture from the aqueous coating. The sheet proceeds to the IR dryer, and the coating is dried over the ink. The second set of knives provides either hot or ambient air to remove additional moisture or cool the product.

Rick Alberts, lead operator on the 756, confirms that the Prime IR dryer enables running higher speeds of up to 15,000 sph. “It's very efficient,” he notes. “We're able to bring [jobs] down to the lower end without cooking the sheets.”

The Zoom offset pressroom employs 10 operators during the day shift and six at night. In addition to the two Ryobi UV presses, the company also has a 5-color, 40" Komori Lithrone that was recently upgraded with Epic Delta Dampening, as well as three multi-color Ryobis in 22", 20" and 18" formats. Other capabilities include a full-service bindery, mailing/fulfillment services and variable-data digital via a Xerox DocuColor 6060 press.

Zoom's prepress department runs an Artwork Systems Nexus workflow and Agfa CTP equipment—:Sherpamatic and Sherpa 24 and 43 proofers, an Agfa :Accento platesetter with L50 Autoloader, plus an HP DesignJet 1050 with SpinJet 1000.

For the smaller 3302 and 582 Ryobi presses, Zoom uses an :Azura C85 platesetter. An Agfa plate manager holds three sizes of plates and pulls them on demand for the three different press formats.

ONLINE: www.ryobi.xpedx.com, primeuv.com, sunchemical.com, harris-bruno.com, bottcher.com, komori-america.com, epicproducts.com, agfa.com, artwork-systems.com, hp.com/go/graphicarts and xerox.com