WINDER/UNWIND Tension Control

You may know them as winders, rewinds, recoilers or take-ups; likewise, you may know them as unwinds, uncoilers or pay-offs, but they are all the same subsection of web handling. Winders and unwinds are a critical portion of the web handling process. The acceleration, deceleration loading and unloading times need to be minimized, while maintaining quality. Also, accurate tension control at both ends of the process allows better process control throughout the machine.

Contrex (many still call us by our old name Fenner) has been a fixture in the web handling industry for over four decades. This industry has evolved over those years and Contrex has evolved right along with it. As web manufacturers produce higher quality products, at higher speeds, the precise control that Contrex controllers provide has changed from being a convenience for the operator to being a necessity. As a side benefit, better tension control frequently yields (almost surprising) indirect improvements, particularly on printing, packaging and other registration type machines.

Experienced operators can get the best possible performance out of a marginal tension control system, by various frequent adjustments to that fickle system. By changing the tension control to a better suited method, far more accurate and consistent tension result while not requiring ANY operator adjustments.

This white paper builds from the most basic control methods up to more complicated systems. The reader may skim the simple topics and jump to more advanced control methods. Please consult with Contrex regarding the best method for your particular machine. Contrex’s policy is to choose the least expensive (including set up costs) option that gets the job done comfortably. Our application engineers have decades of experience across a broad range of industries.

The Contrex products are a family of very precise speed controllers that give very accurate, easy-to-set process control. These products start out with 0.01 percent accuracy in speed mode and true zero-error in follower mode. By allowing inexpensive 60 PPR ring kits or higher resolution surface speed encoders, they are flexible across a broad range of web applications. Often the Contrex controllers can save significant money by optimizing the performance of much lower cost motors and drives. In other words, higher cost, higher performance drives may not be required in a given application if the right control system is used.