Psychrometric Boundary Layer Analysis in Wrapped Paperboard Pallets during Transit
Polyethylene film wraps trap moisture desorbed by paperboard during thermal swings, elevating internal relative humidity and triggering mechanosorptive failure.
Fluting Profile Collapse
Structural Failure
Mechanical compression of corrugated board causes a permanent reduction in the height of the fluting medium when the board’s structural limits are exceeded. Fluting profile collapse represents the irreversible flattening of the sinusoidal wave structure, which usually occurs during the converting or printing phase. This deformation reduces the board’s caliper and destroys the air cushions that provide cushioning and thermal insulation.
The failure is typically initiated when the nip pressure on flexographic printing presses or die-cutters is set too high.
Pressure Management
During the converting process, the corrugated sheet passes between steel rolls that apply pressure to transfer ink or cut the board shape. If this pressure exceeds the flat crush resistance of the medium, the fluting profile collapse occurs, leaving a crushed core with low bending stiffness. This failure makes the board susceptible to warping and reduces the top-to-bottom compression strength of the finished boxes.
Plant managers must monitor roll gaps and adjust the impression settings to avoid crushing the fluted layer.
Performance Consequence
The structural degradation from a collapsed profile is immediately evident in the box compression test values. A box made from collapsed board cannot support the same stacking load as one with intact fluting. This reduction in load-bearing capacity leads to collapsed stacks in warehouses and damaged goods during transit.