Transforming Art into Science

While the upper blade is driven by the lower anvil ring, there is no equal match of rotational speed between the two knives. Some of the rotational force of the lower anvil ring is lost via radial friction between the two blades. The more overlap that exists, the more friction between the blades and the slower the upper blade will rotate compared to the lower anvil ring. Therefore, the lower anvil ring must rotate even faster than the web to compensate for this loss in speed caused by friction. Sometimes an under-sped slitter nip can be identified by the appearance of a “web bubble” ahead of the slitter.