14 WESTERN PALLET
compression strength. As shown, as the pallet deck sags or deforms due to the weight of the packaged product the compression stresses become higher and more concentrated. A stiffer pallet deck will deform less and distribute the compression forces more uniformly, and therefore the maximum stresses are reduced. This clearly implies that pallet stiffness can be used to reduce packaging costs, product damage, and leakers of liquids when bottles or pails fail.
This interaction between packaging and pallets was recently studied by Chandler Quesenberry¹ and Mary Paz Alvarez Valverde², both, recent graduate students in the Packaging Systems and Design program at Virginia Tech.
The effect of pallet deck stiffness on the compression strength of corrugated containers
According to Chandler Quesenberry, increasing the wood pallet deck stiffness by simply increasing the thickness of the deck boards by ¼ of an inch resulted in an effective increase in average box strength by 16.3%. He indicates that this is approximately the difference in strength of a 40 ECT and 32 ECT box. Based on then 2019 prices of a unit load containing 48, 16” X 10” X 10” boxes, switching from a 40 ECT to a 32 ECT box saves about $4.31/unit load. At the time the increase in pallet cost was $3.24 for a net savings of $1.07/unit load. While this is not much it adds up depending on number of unit loads shipped. The mid-size manufacturer usually ships 200-400 thousand pallets a year, thus $1.07 savings per unit load could results in a $214-$428,000 annual savings. When one compares the weight reduction of the packaging to the weight increase of the pallet, the weight of the unit load does not change significantly. Thus, the change does not significantly change the sustainability of the unit load.
However, if this unit load contained five layers instead of four and 60 boxes instead of 48, the metrics change significantly. The net cost savings would be $2.00 per unit load and the reduction in packaging and pallet mass per unit load would be 1.7 pounds. Thus, the new, stiffer, pallet design results in a more sustainable unit load design. Saewhan Kim who is currently a Ph.D. student at Virginia Tech packaging program, conducted an extensive study to quantify the environmental impact of the proposed holistic unit load design idea by Quesenberry. He found that the environmental impact of the unit load system can decrease as much as 23% if the interaction between pallet stiffness and corrugated boxes are used to optimize the unit load.
Pallet Design (Cont'd from Page 11)