ECS-R Roll-to-Roll Unwinding & Winding Unit with Tension Control (W=200mm, Max. 50 N), ERR2RUWU

A Roll-to-Roll (R2R) Unwinding & Winding Unit with Tension Control is the mechanical backbone of continuous pilot and industrial manufacturing lines. In advanced energy materials processing—such as slot-die coating of battery electrodes, fabricating solid-state electrolyte sheets, or manufacturing composite polymer membranes—maintaining precise web tension is critical.

The primary challenge at the unwind stage is that the roll's radius (R) continuously decreases as material feeds into the machine. Modern high-end lab and pilot scales utilize AC servo motors or precise magnetic particle brakes regulated by ultrasonic sensors that continuously measure the changing roll diameter. Unlike the unwind zone, winding requires taper tension. If a roll is wound with constant tension from core to outer layer, the outer layers will compress the inner layers, causing structural defects known as "telescoping" or "starring." The controller deliberately reduces the target winding tension by a set percentage (typically 10% to 40%) as the roll diameter expands.

R2R units monitor real-time web tension through two primary hardware configurations: (1) Load Cell System (Direct Force Measurement): The web passes over a specialized idler roller mounted on dual cantilever or low-profile strain gauge load cells. This provides an immediate, highly accurate measurement of the physical force (typically measured in Newtons or Newtons per millimeter of web width). It is ideal for rigid substrates like copper or aluminum current collectors. (2) Dancer Arm System (Position-Based Storage): The web loops under a weighted or pneumatically loaded pivoting arm. If the line tension increases, the dancer arm rises; if it slackens, the arm drops. A rotary potentiometer tracks the arm's position, and the PID controller adjusts the motor speed to keep the dancer centered. Dancers are highly effective at absorbing sudden mechanical shocks or eccentricities in out-of-round material rolls.

References:

H. Cheng, et al., Li-Ion Battery Electrode Manufacturing Control System in Winding Process: Tension Control in Industrial Complex Roll-to-Roll Winding Machine Via SMC-FLC Hybrid Control Method, J. Manuf. Sci. Eng. Nov 2023, 145(11): 111007

J. Noh, et al., Control of Fluctuational Tension in Roll-to-Roll Manufacturing Systems under Acceleration and Deceleration Conditions, International Journal of Precision Engineering and Manufacturing-Green Technology, 2025, 12, 1159–1174