Closed Loop for Short-run Offset

As digital printing battles offset lithography for the hearts and minds of print buyers, offset has armed itself to a whole new level. The latest firepower in the sheetfed sector comes from on-board and press-side control tools to reduce makeready and production time. The warring factions have learned that improved quality is about more than bar charts and monthly averages—it's an essential strategy for reducing manufacturing costs.

After years of R&D, the advantages of closed-loop color have finally arrived for sheetfed printers. Heidelberg shows its Prinect Inpress Control at Graph Expo this month—the first closed-loop color device for sheetfed presses that can capture spectrophotometric data from the color bar at full press speed. Utilizing six spectral sensors across the width of the Speedmaster CD 74 or eight sensors on a Speedmaster XL105, it can analyze an entire 4-color bar within 16 sheets.

“Because you don't have to stop the press to pull sheets for measurement, it saves about eight to 10 minutes and approximately 150 sheets during makeready,” says James Mauro, Prinect product manager for Heidelberg USA. “Short- to medium-run printers profit the most, because reduced setup time is the biggest benefit.”

Heidelberg plans to roll out the product as a field-installed option for new presses beginning in November, but it won't be available for delivery with new presses until April 2007.

For those who prefer to measure sheets offline, other press manufacturers continue to advance speed and effectiveness of these tools. KBA, for example, has upgraded its Densitronic S press-side color analysis system, which can read spectral color data and ink density at any location on the sheet, making it possible to bring a running press up to color in minutes. A new Dynamic Control option hastens the process by reducing reaction time to changing press results.

“We find it easy to schedule five or six makereadies in an eight-hour shift,” says Dennis Muraro, GM at Milwaukee's C Graphics, a division of The Garvey Group. Adding Dynamic Control to its Densitronic S system is key to competing at run lengths that would force C Graphic's competitors into retreat.

“It's a sequential thing,” says Muraro. “We optimized the press—we really got into optimizing the accuracy of our CIP3 results—and now the next step has been Dynamic Control.”

There's no doubt that Print Production Format (PPF) data produced from CIP3/4-compliant systems has been a powerful weapon during the battle for short runs, but reruns can also benefit from KBA's color control expertise.

“I took flat sheets from a previous run and scanned them into Dynamic Control,” recalls Dave Vieweg, pressroom manager at C Graphics. “By the time we'd run 100 impressions, I could start saving sheets. It understands what the press is giving you. It makes the adjustments a lot faster.”

Being competitive at three-digit copy counts is business as usual. “Plate consumption has doubled over last year,” says Muraro. “It's amazing what we can do in an eight-hour shift.”