Structural Failure
Corrugation failure represents a departure from the uniform wave profile required in the structural core of combined packaging board. A fluting defect occurs when the fluting medium undergoes fracture, leaning, or collapse during the corrugating or gluing stages. This failure undermines the vertical load-bearing capacity of the board because the flutes cannot distribute forces evenly across the linerboard.
Visual inspection often reveals crushed zones or irregular spacing where the paper failed to form the intended sinusoidal shape.
Mechanical Cause
Excessive steam pressure or insufficient paper moisture can make the fluting medium brittle, which leads to fracturing at the flute tips as they pass through the corrugating rolls. Another common mechanism is lean flutes, which arise when the paper is pulled unevenly before the adhesive sets, causing the arches to tilt. If the clearance between the corrugating rolls is incorrect, or if the rolls are worn, the paper medium may be crushed during forming.
Maintaining proper brake tension on the roll stand and ensuring the corrugating rolls are aligned minimizes these defects.
Compression Loss
Reduced structural performance directly affects the performance of the final carton on automated packaging lines. Defective fluting leads to reduced flat crush resistance, which increases the likelihood of carton collapse during transport. Production facilities run crush tests on sample coupons to detect these structural weaknesses before the board is converted.
