Tension Control:
A dancer is one system that can be utilized for tension control, however it is typically used for compensation rather than true control. A mechanical spring or air pressure setting is typically utilized causing the dancer arm to move up and down with the changes in material tension causing compensation for the varying tension of the material. Neither setting can be adjusted accurately or with good repeatability. In addition, the spring adjustment can not be done from a PLC and air pressure adjustment from a PLC is not very easy. Also, a typical mechanical dancer system does not compensate for wear of parts, increase friction in sheave bearing, etc. Because it does not measure the actual changes in material tension. Closed loop control can be done with a dancer.
