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Sheetfed Drying/Curing — No Limitations

February 2004 By Erik Cagle
Senior Editor
Your ultraviolet (UV), infrared (IR) or hot air drying/curing system serves a valuable purpose for sheetfed offset presses. It dries, it cures and, most of all, it stays out of the way of completing the job.

And that’s just the way it should be, according to John Crosby, project manager for drying systems at Baldwin Technology. “It’s all about flexibility,” Crosby says. “The customer does not want the drying system to be any kind of limitation. He wants to be able to run the full range of substrates, and at high press speeds. He doesn’t want to limit the process because of the dryer.”

Baldwin’s latest offerings are the GraphiSet GS1 IR drying system and the GraphiSet GS4 IR and hot air drying system. The GS1 is geared toward low-pile delivery presses. It features short wave IR modules with water and/or air cooling. The GS4 is a fit for sheetfed presses with a high-pile delivery and coater, and can dry inks and water-based coatings on paper, card and carton stocks.

It is important not to base decision-making solely on current needs, admonishes Bill Bonallo, president and CEO of technotrans america. Current and future UV potential should be considered in order to make an investment that is beneficial in the long term.

“It’s a proven fact; few printers, if any, know what kind of opportunities may come their way once they have UV capability,” Bonallo says. “These future opportunities may require additional UV hardware to accomplish. We try to configure our systems to offer the maximum flexibility, on the widest variety of applications and substrates, looking into the future, as well.”

technotrans america is the exclusive representative for IST UV curing systems for sheetfed applications, the latest of which is a concept of UV curing in an inert atmosphere, called CoolCure. The technology, while common to web presses, is relatively new to sheetfed applications. It involves replacing the oxygen with nitrogen in the area where the curing takes place, increasing efficiency. It results in lower output of the UV curing system necessary to cure the ink or coating, reducing heat to the substrate.

New Generation Dryer

technotrans has also introduced a new generation, thermal drying system designed to provide the highest levels of ink- and water-based coating drying at maximum rated press running speeds. The system is configured to provide drying starting from the first sheet of the delivery, and its design allows complete interchange ability with IST UV components.

One of the biggest questions is whether the dryer can actually perform its duty on a given substrate, according to Chad Carney, director of marketing communications for Research Inc. “When they’re printing on gloss stocks or nonporous materials with their standard printing system, they’re typically using a water-based ink and they’re not going to dry on a nonporous substrate,” he says. “So when they’re looking to add the dryer, in that case they don’t have to switch their ink or use a solvent-based ink, so they can achieve a faster drying time.

“With our infrared systems, they can simply add that on to their sheetfed press or their mail base if they’re doing direct mail. They don’t have to make any changes to their existing equipment—just an IR dryer behind the print station.”

Models 5060 and 5061 are the latest additions to the Speed-Dri IR drying system line. The 5060 dries a 4x10˝ path with one module or an 8x10˝ path with two modules with four kilowatts of voltage. The 5061 can dry print target areas up 4˝ wide.

When printing on plastics, conventional inks give way to UV inks, which provide an instant cure, notes Elinor Midlik, president of Prime UV Systems. “Because you’re installing it in the sheetfed press after each color unit, one of the characteristics that you’re looking for is a very compact system,” she says. “Another quality is a cool UV system that will not heat up the press.”

Prime UV’s sheetfed drying systems feature double cool UV lamps that increase the speed of the curing process while eliminating heat to the substrate. The Prime IR Action Dryers are designed to provide high-speed drying of adhesives, inks and coatings, and can be installed on existing sheetfed presses.

Customers are looking for value-added solutions that expand their capabilities and efficiently handle their core business, according to Keith Tap, vice president of operations for DÜSSELDORF, GERMANY— U.S.A. “Core business in this case is defined by high speed, top-quality printing using conventional inks and acrylic coatings,” he says. “Value-added performance we see as considering variables of non-absorbent substrates—plastics, foil laminates, synthetics, etc.—specialty inks and effects coatings. In this scenario, these variables spell the need for hybrid UV equipment.”

Grafix offers system components that are interchangeable and interface with the original equipment manufacturer press operator console, providing centralized control of all dryer operations from a common screen. Grafix supplies full and hybrid UV drying systems for all sheetfed presses.

Deciding which drying or curing system fits your needs, and that the drying system matches the chemistry being applied, is only the first step, according to William Fuchs, president of FDV Inc. Fuchs believes a printer should investigate the dryer manufacturer’s equipment, features, technology, service and installation, and associated costs.

Fuchs sees UV as the preferred system due to its instant curing of inks and coatings, the highest level of gloss and rub when coating, and its ability to work well on plastics and sensitive substrates.

“However, all of this comes at a cost,” he warns. “UV curing equipment is very costly; the inks and coatings cost more than conventional inks and water-based coatings. The press and rollers/blankets must be converted to be compatible with UV. Plus, a substantial amount of electrical energy is required to operate these systems.”

Some Drying Firsts

Fuchs adds that FDV introduced the first shortwave IR dryer into the U.S. market, as well as the first standalone hot-air knife drying system for water-based coatings. It also offers color interstation and end-of-press UV and IR curing systems.

The compactness of the delivery area in low-pile presses makes IR drying more problematic because of space, excessive heat and pre-mature wearing of parts, according to Margaret Bain, sales and marketing coordinator for Accel Graphic Systems. Many of the safety features found on larger IR units, she notes, are not available on smaller presses.

“Because more printers are doing multicolor work, dryers are becoming necessary for faster turnaround time and higher quality printing,” Bain says. “Drying systems also reduce spray powder usage and set off or blocking.”

Accel Graphic Systems manufactures the Tempest hot air dryer, which uses PTC thermistors instead of IR elements in the drying process. She notes that the thermistors never reach a temperature in which paper could be ignited, eliminating fire risks. The Tempest can be used for drying inks and water-based coatings.

When it comes to choosing a drying system, reliability is the top factor that printers need to consider, says Gene Van Horn, advertising manager for Printing Research. Curing a job is just as important as laying down the ink, he notes, and a quality system must be ready to operate at optimum performance at all times.

“An ideal system would be simple and compact in design, with few or no moving parts to overheat or wear out,” Van Horn says. “In our opinion, the best UV systems use refrigerated deionized water to filter out the heat radiated from the UV lamps and inside the press. Systems using air to cool their UV lamps must include high-volume air exhaust systems to evacuate the heat and air from inside the press.”

Quik Dry IR drying systems from Printing Research are designed specifically for ink-only applications to accelerate the drying process. The Air Blanket IR system uses a combination of infrared heat and forced air management, and is designed for both sheetfed and flexo presses using inks and coatings in tandem.

Printing Research also offers a pair of UV curing systems, the Cold and Zone. Both systems are shutterless, reducing the odds of mechanical failure.

Oxy-Dry Corp. offers the DuoTek line of IR drying equipment for conventional inks, as well as the DuoTek UV hybrid curing system for sheetfed printers mixing UV coatings with hybrid inks. PI
 

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