INKETC.: Keyless Ink Trains for Offset

At Graph Expo last month, Goss International announced that its DigiRail technology is now available for commercial web presses. DigiRail systems can be retrofitted to some existing Goss presses and are an option for new M-600 and gapless Sunday models. The highly precise digital inkers replace traditional 'open fountain' ink delivery, reducing waste and makeready time while improving print quality.

DigiRail, which earned the PIA/GATF InterTech Award in 2003, features digital ink pack devices housing low-torque, inline gear pumps. The pumps feed ink pulses to the ink train through individual valves that are controlled digitally. More than 50,000 individual ink packs have been installed worldwide and, Goss says, are highly proven on its newspaper and insert presses.

DigiRail's ink-metering valves are each pulsed by separate digital signals. Varying the open time of the pulses allows precise ink volumes to be delivered. The number of ink packs varies according to web width, with the individual valves covering zones equivalent to those of a traditional ink key.

Digital control of ink flow complements digital workflow and presetting capabilities and offers several fundamental benefits, according to John Dowling, engineering director in the Goss Research & Development Department. “Because ink is delivered to the ink train with more precision and with no contamination, presetting is faster and more accurate, start-up waste can be reduced, and ink density and color variation issues are minimized during operation,” Dowling says. “After extensive testing on demanding technical forms, and minor modifications, DigiRail technology can now bring these same benefits to commercial presses printing at up to 100,000 impressions per hour.”

The flow of ink to the metering valves is constant for a given press speed, and the amount of ink fed to each 40-mm zone across the web is adjusted to match ink coverage requirements by changing the digital on/off pulse rate of each valve, according to Dowling. As a result, ink adjustments can be made in increments as small as 1%, the response is predictable and repeatable, and the ink volume is not sensitive to temperature or viscosity. Dowling points out that excess ink is recirculated within the sealed system, reducing consumption and contamination from lint, dust or dampener fluid.

Commercial printer Taylor Corp., North Mankato, MN, became the first U.S. printer to incorporate the short-train, keyless Anicolor system, which Heidelberg developed jointly with Sun Chemical. Taylor installed four Speedmaster SM 52 presses with Anicolor, a zoneless short inking unit with dampening system. The technology won a 2007 InterTech Technology Award. “The biggest advantage of Anicolor over traditional presses is color consistency,” says Craig Krone, Taylor's VP of information and technologies for personalized business products. Previously available only for process CMYK colors, Heidelberg introduced a 10-color version of an Anicolor SM press at Tokyo's IGAS show earlier this month.

KBA offers the zoneless Gravuflow inking system on its Genius press, which is a waterless offset machine. The 20´´ Genius was an InterTech Technology Award winner in 2006.