Preventing Mechanical Ink Set off Contamination in Converted Flexible Packaging Web Stock
Prevent mechanical ink set-off in flexible web stock by matching tension taper curves to core pressure limits and verifying cure thresholds.
Pfeiffer Pressure Model
Meaning
Mathematical equations calculate the internal radial pressure within a wound roll of film or sheet based on winding tension and material properties. Application of the pfeiffer pressure model allows manufacturers to predict the stresses that lead to roll defects like blocking or starring. The model assumes that the roll is an orthotropic cylinder where the radial modulus varies with the local pressure.
Tension Calculation
Input variables include the web thickness and the winding tension profile as well as the material stiffness and the roll diameter. By solving the pfeiffer pressure model, the system determines the distribution of tension from the core to the outer lap.
Radial Stress
Internal pressure peaks often occur near the core where the cumulative force of the outer layers compresses the material. If the pfeiffer pressure model predicts excessive stress, the operator can reduce the taper tension to prevent the film from sticking to itself.
Roll Stability
Creep and stress relaxation change the pressure distribution over time while the roll is in storage after the winding process is complete. Using the pfeiffer pressure model to optimize the initial winding parameters ensures stability. Rolls that are wound too tightly may crush the core, while those wound too loosely will slip or lose their shape during handling.