Industry Facts

Slitting Terms & Technology

Shear Slitting:  Two part blade system acting to shear the web like a rotating pair of scissors.  Typically yields the highest quality cut and is often used in high speed applications.

Score, or crush, slitting:  Hardened rotating blade pressed against a hardened anvil.  The material fed through a score blade system is crushed flat and parted using the pressure of the score blade.  Lofty materials, laminates, textiles, and others can be cut using this method. 

Razor Slitting:  Stationary razor placed in the web path cutting the material.  Best used when cutting thin, non-abrasive materials.  The simplest of all slitting methods.

Hot Knife Slitting:  Using either a stationary or rotating heated blade to cut and fuse the edge of materials.  This is a slower but necessary method for some materials.

Ultrasonic Slitting:  Uses special cutting head to cut and fuse materials.

Web Tension Description

Closed Loop Tension Control:  Tension control where measurement devices (i.e. load cells) send feedback to a controller directly measuring the tension.  The controller, in turn, sends a signal to a motor drive or brake to change or maintain a preset tension.

Open Loop Tension Control:  Tension control based upon measuring web position or roll diameter.  The diameter of the roll, or position of the dancer, is measured and the controller makes necessary adjustments based on predetermined calculations.  Using this system, the actual tension is not being read but rather calculated.  This method is best used in a stop/start application or where tension is very light.

Winding Terms & Technology

SIMPLEX vs. DUPLEX:  Winding up slit materials on one or two rewind shafts.  This is typically dependent on material properties.

Turreted Winding:  Dual position unwinds/rewinds that rotate into position for continuous operation.

Baggy Edge:  Selvage edges and gauge variations lead to a soft side on a roll – this edge will bag when unwound.

Accumulator:  Equipment designed to fill up with material while removing a finished roll or starting a new roll.  Web tension is maintained throughout the process.  This allows for continuous, uninterrupted line flow.

Differential Winding:  Allowing individually slit webs to wind at their own rate.  Tension for each slit roll will be maintained and the same.

Blocking: Blocking is a term used to describe a web on a master roll that sticks to itself as it is being unwound.

Gauge Banding: The gauge of material is the thickness of the web. Gauge band only describes a web which has variance in thickness across it's width.

PLI: Pounds per linear inch. 1 PLI is the equivalent of hanging a 1 pound weight at the end of a 1 inch strip of material. For a 60" wide web width, 1 PLI tenstion would be the equivalent of hanging 60 pounds of weight at the end of the web.