Certain problems in web handling can be challenging because they tend to get worse with time. Consider mechanical resonance. The longer you run at resonant vibration conditions, the worse the problem will initially get. Yet the effects of resonance are usually limited because of damping and in many cases are not even perceivable. There are conditions that are much more challenging because they are accumulating or self-exciting. These problems not only get worse with time, they may get much worse with time. The response or response rates are ever-increasing and unbounded except by breakdown or shutdown. This paper is a mechanistic survey of some of the toughest problems in web handling including:

Accumulating

-Air Bubbles Behind Nips

-Gage Bands in Wound Rolls

-Loose Lanes in Locked Core Winding

Resonant

-Guide Control

-Tension Control

-Roller Critical Speed

-Wound Roll Vibration

Self-Exciting

-Calender Barring

Interweaving on Simplex Winders

-Knots in Wound Rolls

-Telescoping on Core Supported Winding

-Wound Rolls that Uncoil After Cutover