Elimination of scratches during punching and forming: That's the motto of the TruPunch 5000, which has an active die that works like a second punching head from beneath. "We were a test customer for this new machine option for two years. I was skeptical during the preliminary discussions. Could this kind of mechanical principle really work? But when I saw the first prototypes, I understood that it would! The active die has changed a variety of our processes, and even the machine operators really appreciate it," reports Manfred Wujesch, Technology Lead for Punches and Combination Machines at Wincor Nixdorf AG, the world leader in IT solutions and services for retail and banking, as well as manufacturer of ATM machines, kiosk systems, and computerized cash registers. In the company's sheet metal processing area, five punching machines and three combination machines from TRUMPF are at work, including the latest generation of the TruPunch 5000 with the active die.

Wincor Nixdorf often processes surface-treated or galvanized material, zincor sheet metal and aluminum. Many of the parts are used in applications where they are visible, so eliminating scratches and burrs is very important. "To avoid scratching, we used to manufacture sensitive materials primarily on the combination machines with lots of laser use. Now, we can use the punching machine as a more cost-effective alternative. Every time the sheet metal is repositioned, the die moves downwards a little so that the underside of the sheet won't get scratched," says Jens Levermann, Punch Technology Lead at Wincor Nixdorf. The combination of active die and roller deburring has resulted in a new standard of quality for coated and soft materials like zincor or aluminum, because follow-up processes like hand deburring due to scratches can be eliminated. Both run-times and scrap have been noticeably reduced in this manner. And downtimes have also been reduced, because employees no longer need to search for the causes of scratches during the fabrication process - with the active die, they simply don't occur.

The Active Die

A new extra in the TRUMPF punching and combination machines makes scratch-free processing possible: the active die. Adjustable in height, it is installed below the worktable. The matrice is retracted so that it does not touch the sheet while it is being positioned or moved on the machine. This prevents scratches on the back side of the metal. Now the sheet metal lies always flat with the work table, which means it can be machined closer to the clamps, as it does not camber up when being processed. That reduces the area that cannot be processed and cuts material costs. Moreover, this active die simplifies programming because it is no longer a disturbing contour that would have to be taken into account when calculating the positioning path.

The active die also gives users greater leeway in processing. With this option larger and deeper areas can be formed using entirely new tools. What's more, forming in the upward and downward directions can be completed in a single setting. That's because the active die functions like a second punching head and enables active forming from below. The sequence, seen in detail, is as follows: The machine positions the sheet metal with the matrice retracted. Once the plate has reached the desired position, the punching head secures the workpiece from above whereupon the matrice executes its active forming stroke from below. Finally the punching head and the active die retract into their original positions before the sheet metal is repositioned. Thus production processes run completely without danger of scratches.