Digital roll-to-roll web processing revolutionizes printed electronic production
The result can be seen in Figure 2. In this example, the press uses two successive controllers. But now the step change signaled by the green section controller doesn’t create a cascade effect upstream. Along with decoupling to prevent feedback, the controller initiates a response to step reduction in tension control in one-fourth the time compared to typical controllers.
With the solution described, tension can be controlled for up to eight axes. One or multiple points can be selected to be left uncontrolled. At the selected axis, line speed is held constant. At a standstill, web tension can be maintained. In fact, multi-axis tension control increases standstill web tension accuracy by a factor of two to four. Achieving the desired standstill web tension is also much faster. Without decoupling, a setpoint can be achieved in 13-14 seconds; with decoupling, it takes three to four seconds.
During acceleration, tension control decoupling ensures the web is stable as soon as full production speed is reached, compared to a delay of five seconds or longer with coupled control. And when tension setpoint changes occur during runtime, the transient response with decoupling takes about one second, compared to about four seconds with coupled control.
Not unlike digital printing, the adoption of roll-to-roll web printing will accelerate as the technology demonstrates its ability to provide high accuracy at high speeds. At the outset, however, the process with tension control offers several bottom-line benefits: the roll-to-roll web starts faster, saving time and increasing output; longer periods of web stability reduce waste and increase yield; and less tension deviation on the substrate improves registration and enables the use of more sensitive material.
And, because printed electronic material can be 10 times the cost, or even significantly more expensive, than typical substrate, decoupled multi-axis tension control technology promises a significant payback. Original equipment manufacturers (OEMs) get an off-the-shelf solution providing the most stable tension solution for roll-to-roll machines. The result is faster time to market and easier implementation thanks to integrated components, including drives, function blocks, and software controls. By enabling tight registration and greater throughput, decoupled tension control can handle the challenges OEMs face when building roll-to-roll presses today—and promises a bright future for large-scale printed electronics manufacturing tomorrow.
- Bosch Rexroth provided the information. Edited by Mark T. Hoske, content manager, CFE Media, Control Engineering and Plant Engineering, mhoske(at)cfemedia.com.
- Multi-axis tension control solution allows the web to be decoupled into separate tension control zones. Tension can be adjusted as required in one zone area without destabilizing the entire web.
- Could a multi-axis tension controller help improve performance of your web-based application?
Rexroth web tension and printing solutions