I’ve been dying to write about this. When I was at the PRINT show, I got a call from Dan Maurer, Heidelberg’s VP of Postpress Product Management, asking me to come take a look at the new “frog folding” technique they were demonstrating on the show floor. He said they were nearly doubling the production speed for signature folding. I wanted more details, but he said I had to come and see for myself.
Of course I broke land-speed records to get to the booth (not an easy thing to do in heels, by the way). When I got there I was shocked at what I saw. Heidelberg developed a way to increase productivity for signature work by rotating the sheet to feed oblong with a special twin lay attachment and pneumatic gate in the first folding unit. They call it “frog folding” because the sheets “leap frog” one another into two parallel side lays. Confused yet? It’s a little hard to explain.
Steven Calov, Heidelberg’s Postpress Product Manager sent me an explanation of the process:
“Our ‘frog fold’ solution achieves both top folding quality and dramatically improved productivity by combining lower-speed production with a high number of cycles, based on a simple turn of sheets in the feeder. Here’s how it works:
Sheets are fed oblong at the feeder. Depending on the sheet format, this can lead to an increased performance of approximately 30 percent at the same machine speed, due to the shorter infeed length of the sheet (see Illustration 1). Illustration 1: Rotating sheet to oblong fold, gain 30% productivity at the same mechanical speed.
Until now, the limitation of oblong feeding has been transferral of the speed problem to the second folding station, because there was no reduction of the infeed length and the full sheet length still had to be transported (see Illustration 2).Illustration 2: What could be done previously.
To resolve this problem, Heidelberg developed a pneumatic twin-lay device that enables the alignment and transport of folded sheets in the second folding station at two parallel side lays, reducing the speed of the second station by 50 percent. In so doing, the sheets travel over or “leap frog” one another in order to align with the register of the twin lay. While the first station runs at full speed, the second station functions in a different way to increase productivity (see Illustration 3).
Illustration 3: Heidelberg’s Twin Lay.
There are additional advantages. The first fold enables the user to line up all the pages head to head, eliminating the lateral movement that could occur in traditional folding, and yielding two parallel folds in the eight-page section. The benefit here lies in better control of crossovers. Overall, the net result of simple modifications like these is to increase productivity by means of the oblong feeding of the sheet, and to improve the quality of the fold by virtue of the slower speed in the second station, making the folding process even more stable.”
Pretty cool. To give you a few stats to consider, on average, you could expect to run production numbers of about 8-11,000 sph on a modern folding machine. With this new configuration, you could be running 17-22,000 sph, depending upon the quality of the stock. They were running at 22,000 sph at the show.
This special configuration will require the modification of folding schemes and potentially a larger buckle plate folder, but all in exchange for higher output, increased quality and savings over the entire production chain. Sounds like a good deal to me.
Heidelberg’s high-performance Stahlfolder TD and TH series folders will offer the pneumatic twin lay device as an attachment on all new purchases from Q1 2010.
For more information about this innovative new device, please contact your local Heidelberg Postpress Specialist, or contact Stephen Calov directly at Steven.Calov@heldelberg.com