Precise unwind tension control sometimes requires brakes with a wide torque range to meet the wide range of materials (tensions) and widths run on a line. This is further complicated by the larger rolls (coils) to be unwound (uncoiled). To put this in perspective, a roll with 72″ OD and 6″ core will require a 12:1 decrease in air pressure from start to core. If you start at 60 PSI, you would finish the roll at 5 PSI, this leaves little adjustment for a wide tension range for lighter/heavier materials and wider/narrower widths.
Wichita KKB brake designs are very proportional from8 PSI to 80 PSI or a 10:1 ratio, the high performance ModEvo design is good to 3/4 PSI for a 20:1 ratio. To accommodate the demands of modern equipment, Wichita has many creative designs available to increase the range of control of unwind brakes by using multiple actuators.
Below is a photo of a special “Tandem” Wichita ATD 208/214 KKB (Kopper Kool Brake) used on Pro Eco slitting lines with the Core-Flex unit for exit tension/elongation control. These lines require precise uncoiling tension control for a wide range of widths and gauges of material, using a “Tandem” Wichita KKB allows precise control over a 53:1 range. Using the Kopper Kool design with proper water cooling system allows for high speed operation up to 140 HP. In addition to the ATD 208/214 Tandem KKB, Wichita offers other size combination’s with even higher capacity with precise control.
For Paper, Film and Foil processing, Wichita Clutch offers the ModEvo modular Tension Brake. This family of products allows Torque Inc. application engineers to select an optimal solution for your application with a variety of rotor’s, friction material and actuators. We have had good success using these products on low speed coil processing lines, where heat is limited and the cost of operating a KKB (Kopper Kool Brake) is prohibitive. In addition, we can engineer unique multiple caliper solutions using Kobelt Calipers for heavy duty applications.