Piezoelectric Stress Wave Analysis in Rotary Die Scoring Operations
Piezoelectric stress wave monitoring detects cartonboard score cracking in real time by capturing high-frequency elastic strain transients at rotary die nips.
Stress Wave Analysis
Propagation Monitoring
Diagnostic testing methods evaluate the structural integrity of materials by tracking the propagation and attenuation of high-frequency elastic waves through a solid medium. Known as stress wave analysis, this technique is used to inspect both rotating machinery and stationary composite structures for internal defects. The waves are generated by mechanical impacts, frictional wear, or micro-fracturing within the material.
Signal Interpretation
The velocity and amplitude of the propagating waves change as they encounter internal barriers such as cracks, voids, or boundaries between different material layers. Sensors capture these changes, and the recorded data is processed to calculate the depth and size of the defect. In multilayer paperboard, for example, a decrease in wave velocity indicates a loss of adhesion between the paper plies.
This allows for the non-destructive testing of finished products before they are shipped. By tracking these propagation variations over time, operators can map the progressive degradation of the substrate under cyclical loading.
Machinery Assessment
Converting plants use this methodology to assess the condition of heavy bearing assemblies on paper mills and corrugators. By isolating the high-frequency waves produced by microscopic metal-to-metal contact, maintenance teams can identify bearing wear long before traditional vibration analysis registers a fault. This predictive capability reduces unscheduled downtime and prevents costly damage to the rollers.