Online Acoustic Wave Sensing for Paperboard Score Quality Control
Inline acoustic wave sensing detects sub-surface paperboard delamination during scoring, stopping un-creased board defects before downstream cartoning line jams.
Acoustic Wave Sensing
Velocity Propagation
Non-destructive testing methods for paperboard evaluation rely on high-frequency sound propagation to determine mechanical stiffness without destroying the web. Real-time acoustic wave sensing measures the time of flight of an ultrasonic pulse through the sheet to calculate both in-plane elastic properties and fibre orientation anisotropy. This measurement stops being reliable when the moisture content exceeds fifteen percent because the water molecules damp the acoustic signal.
High-density grades such as linerboard require lower transducer frequencies to penetrate the structure than thin tissue papers. Mechanical testing of paperboard traditionally requires destructive tensile tests, which cannot provide continuous data during a high-speed production run.
Tension Correlation
Dynamic transducer arrays are positioned across the web to capture variations in both the machine direction and cross direction. Fast propagation through the sheet corresponds to higher elastic stiffness and denser fibre network bonding. By comparing the velocity profiles, operators identify regions of structural weakness before the reel reaches the winding station.
This system operates without physical contact to prevent marking on coated finishes or lightweight tissue grades.
Web Performance
Quality control systems on high-speed corrugating lines use the velocity values to predict the compressive strength of the resulting board. Low acoustic velocities correlate with poor flute structure and board crushing during converting. These readings enable continuous monitoring on the paper machine to adjust wet-end parameters and refining levels before the run is finished.
The data are processed within milliseconds to allow immediate tension adjustments.