Often the Torque Hold function provides adequate tension during most of the index, but may not provide enough tension for a good, clean cut. The knife may require a very taut web if the web is stretchy. In this case, Torque Boost is required.
Torque Boost is used instead of Tension Boost, because the turret spindle is not running in tension control during an index. The spindle is running in Torque Hold mode. A boost in torque will create a boost in tension.
For some stretchy products such as polyethylene stretch wrap, a 300% torque boost may be required to provide a clean cut. Torque boost will tighten the web, but will also cause the web width to shrink (neck in). Torque boost should be applied as late as possible just before the knife cut. Torque boost will end when torque hold mode ends – at the cut or a web break.
Torque boost should be used only if the product calls for it. The lowest level of boost that will perform satisfactorily should be used. Downsides of torque boost are that the outside layers of your roll will be wound with a high tension, and that the product width will shrink.