Predicting the Effect of Pallet Overhang on the Box Compression Strength

Unit loads, consisting of pallets and corrugated boxes, are one of the primary forms of storage and distribution of packaged products. The corrugated box’s compression strength can easily be affected by environmental parameters, such as pallet overhang, which reduce a box’s effective compression strength. The effects of overhang on box compression strength have been investigated by multiple researchers, but each previous study used its own unique set of different sizes of boxes made from different materials, limiting the broad comparability of the results and challenging strong statistical analysis. The current study, performed on behalf of the Fibre Box Association and ICPF, aimed to investigate the effects of pallet overhang on box compression strength using four different sizes of corrugated boxes, made from two different board combinations, in order to compare existing values in the Fibre Box Handbook, and potentially explore the possibility of developing a more universal model for predicting the effects of pallet overhang. The four sizes of boxes, for each nominal 32 ECT C-flute and nominal 48 ECT BC-flute corrugated materials, were examined in over a dozen single-side overhang configurations and five adjacent-side overhang scenarios. Compression tests were conducted in compliance with the TAPPI 804 standard. A range of multiple linear and nonlinear regression models based on these test results were developed for this study. These models provide the estimated change in a box’s compression strength due to any overhang, compared to a no-overhang scenario, by percentage. As expected from earlier work, effective box compression strength decreases as the magnitude of overhang increases. Significant differences were found when the same overhang was investigated on the width versus the length side of the boxes. It was also observed that the magnitude of the adjacent-side overhang effect on box compression strength is not simply related to the combination of short and long sides’ overhang effects, but it has a unique effect that is most likely related to the loss of additional box corner support as compared to single side box overhang. The box size relative to the amount of overhang was also a statistically significant factor affecting effective box compression strength in the tested overhang scenarios. This work also indicated the need for further research refining the first-order model and extending it to other materials, box sizes, and box aspect ratios.