Start. Stop. Start. Stop. For anyone who has ever prepared a mechanical, drive-shaft-based printing press for production, this is the standard pre-production warm-up. Manually position the first cylinder and test run the first color. Stop. Manually position the second cylinder and test run the second color. Stop. Repeat for the remaining cylinders and colors and stop again. Then, go back and begin adjusting all of the cylinders until you achieve proper registration and correct color. And, while you're at it, try to conserve paper and ink to save time and money.

True, there was a time in when all of this stopping and starting made perfect sense, and for some printing applications it still does. But fortunately, this herky-jerky dance is going the way of the dinosaur as shaftless, servo-drive technology becomes increasingly affordable for a broader range of printing applications.

Just ask Don Hooley, vice president of production at converter LTi Printing in Sturgis, MI. Hooley knows the ins and outs of both mechanical and servo-driven presses first-hand because he manages the operation of both at LTi.

While the company provides a wide range of printing services, its main focus is on commercial, folding carton and label printing, making it a perfect candidate recently for the Model 8518 Servoflex flexographic printing press from Nilpeter USA of Cincinnati (formerly Roto Press Intl.). Currently, LTi uses its mechanical presses for board and label printing, whereas the Servoflex is used for broader applications including film.

The eight-color Servoflex was introduced at Labelexpo USA 2000. Capable of running at speeds up to 1,000 fpm, it's equipped with combination hot-air drying and UV curing, and 50-in. unwind and rewinds. The gear-free drive system, employing Bosch Rexroth (Hoffman Estates, IL) servo drives connected via a fiber-optic network, permits LTi to run a variety of substrates from 0.001-in. film up to 0.02-in. paperboard carton stock.

Along with substrate versatility, Hooley also appreciates the Servoflex's boost in production speed. LTi's mechanical press prints up to 275 fpm, he says, compared to the Servoflex, which for typical LTi 14- to 16-pt board jobs, operates at up to 450 fpm (64 percent faster).

Speed isn't LTi's only need; quality also counts, and in this case it also cuts—waste. "Whenever we need to stop the Servoflex press to do a roll change or clean plates, for example, when we restart the press, registration is immediate," notes Hooley. He compares this to the several minutes required to regain registration on the mechanical press. "Not only does it take less time to perform these tasks, but we're also generating very little waste in the process."

Elimination of gear marks—the impression waves that can appear during printing on a mechanical press—is a big advantage of servo-driven flexo printing, Hooley says, because it too reduces waste and results in higher-quality products for LTi customers.

"Shaftless technology is nothing new to newspaper, business-form and commercial printers," explains Jim Hulman, printing and converting industry executive for Bosch Rexroth's Electric Drives and Controls division. "Only in the past two to three years has its affordability made it an option for smaller flexo applications, and with the growing demands placed on these presses, servo-driven designs are quickly becoming the new standard for printing speed and quality."

To understand the impact servo-drive technology makes, compare a servo-drive design to an older mechanical design. Mechanical presses use a line shaft, gears, gearboxes, belts, pulleys, and clutches to comprise a mechanical synchronization system—each with its own individual tolerances. When components are linked end-to-end, the tolerances accumulate, resulting in significant deviation, particularly during acceleration and deceleration. On a mechanical press, the acceleration between make-ready speed and production speed can generate significant waste as the mechanical gears wind up, then spring back when a continuous speed is achieved.

Servo drive, on the other hand, provides greater machine flexibility, reduces make-ready time and related waste, and improves print quality by eliminating the shortcomings of the mechanical drive shaft and gear train. On the Servoflex, for example, each print station is individually controlled by a servo drive, and a master motion controller synchronizes all printing operations. The result is a registration tolerance of +/- 0.001 in. compared to a mechanical-press tolerance of +/- .003 in., Nilpeter says.

"Flexographic printing technology gets better every year. It has to in order to compete with other technologies like offset," explains Mike Vandenberg, Nilpeter vice president of engineering. "Everything is constantly improving, from the press plates and rolls all the way down to the materials."

Responding to a customer demand, Nilpeter set out to design its first servo-driven press in early 2000. After reviewing four different servo-drive suppliers, it chose Bosch Rexroth. "We had eight months to develop and build the Servoflex, so we had no time to reinvent the wheel," says Vandenberg. "We needed proven technology, and Bosch Rexroth had the reputation and experience that allowed us to plug them right into the project."

One of the greatest benefits of the Bosch Rexroth package Nilpeter selected was the high level of control and ease of use provided by the programming software. One program provides Windows-based, point-and-click selection of pre-configured algorithms, as opposed to other systems that may require multiple software packages and force the end user to program algorithms.

"With this off-the-shelf servo drive system," Vandenberg says, "we can establish all of the programming ourselves, and we are totally free to customize it, enhance it, develop special applications. That flexibility is priceless."

For converter LTi Printing, the resulting press output is pretty valuable as well. "What's more important," summaries Hooley, "is that our customers experience the benefits—in the form of higher print quality and competitive prices."