Moving from pallet design to the design of the entire unit load, saves pallet users hundreds of thousands of dollars by reducing packaging costs and improving their supply chain performance. The pallet supplier is the key to these cost savings for the pallet user. The pallet is the interface between the product and the unit load handling equipment. By changing the pallet, lower cost packaging can be used. The savings are huge.
Years of research at the Virginia Tech Center for Packaging and Unit Load Design has looked into how packaging, pallets, and unit load handling and shipping equipment interact. This research has made systematic unit load design possible. Pallet suppliers can now offer unit load design as a service, which can differentiate you from the competition and position you as true packaging expert.
When a manufacturer is designing a box, pail, or other packaging for a product to be placed on a pallet, that designer is focused on the compression strength of the box or other packaging. It turns out that the pallet can be used to reduce compression and then reduce packaging cost.
The following are some examples of ways to save money on total unit load costs. These solutions were developed using the new Best Load™ unit load design software.
Plastic Pails of Coating Materials
Figure 1 shows the unit load of coating material in 90 mil, five gallon, high-density polyethylene (HDPE) plastic pails. The maximum compression stress on the pails occurs when these unit loads are stack stored three unit loads high in a warehouse. Each pail contains 45.8 pounds of coating material. The total weight of the product and packaging on each pallet was 1,649 pounds. The diagram below is a histogram showing that the bottom layer of pails in the bottom unit load are under the greatest compression. The Best Load analysis further shows that the bottom pails in the six interior pail columns are under the most compression. The plot in the upper right shows that the interior edge of the pail, on the current pallet is supporting 22.06 psi of compression.
A column of the current 90 mil, five gallon plastic pails (filled) were tested in compression as shown in Figure 2. The average load at failure was 2190 pounds. An alternative, lower cost, 75 mil, five gallon pail was similarly tested and the average load at failure was 1604 pounds. This is 27% less resistant to compression. Therefore, as a first approximation of a pallet deck to safely support product in the 75 mil pail, the compression stress must be reduced from the current 22.06 psi to less than 15 psi. To accomplish this, the pallet deck must be stiffened.
Since the pallet boards act as beams, it was decided to reduce the span between stringers by adding a fourth stringer and by recessing the outer stringers one inch. This is shown in Figure 3. To reduce pallet cost, the stringer width was reduced from 1.5 inches to 1.25 inches. The Best Load structural analysis of this new pallet predicts a maximum compression on the pails of 13.70 psi. Prototypes of the proposed unit load with the new pallet design and 75 mil pails were tested in the field to verify performance. Within three months the new unit load designs were implemented.
The cost per pallet increased by $0.98 and the cost per pail decreased by $0.31. The net savings per unit load was $10.11. This was an annual packaging spend reduction of $209,199.
Twenty-four Packs of Bottled Water
The stacking patterns on pallets can significantly affect the compression stresses on packaged product. Figure 4 is a Best Load analysis of two stacking patterns of shrink wrapped 24 packs of 16.9 oz. bottles of water on a block class wood pallet. The stresses are greatest on the bottom layer of 24 packs. Notice the top two layers are interlocked for stability and the unit load is stretch wrapped. A change in stacking pattern alters the maximum compression stress by 29%. This is a potential reduction of maximum compression stress from 10.2 to 7.2 psi. Whether manually or automatically stacking product on pallets, such changes in patterns have little or no effect on the cost of assembling unit loads.
Therefore this 30% reduction in compression stress on the bottles is free and will significantly reduce leakers and related damage.
Cases of Small Carpet Squares
As we all know, most of the compression strength of corrugated containers is in the corners. Thus, the pallet design should support the corners of the box to optimize box design and reduce packaging cost. The example below is corrugated containers with head space because the carpet pile should not be compressed. The company was using B grade repaired 48×40 pallets. They were using an expensive double wall box. Figure 5 shows a Best Load analysis of this unit load. The red dots show unsupported box corners. The red boxes are supporting the greatest load. Because of this the box must support 919 pounds and Best Load indicates the box can support 967 pounds. Thus the box was strong enough and was working. Using Best Load we modeled the use of a new pallet with selectively placed deck boards to support the corners. This is shown in Figure 6. On this new pallet the target strength requirement for the box dropped from 919 pounds to 494 pounds. On this pallet a single wall box was now adequate to protect the contents. To move from a used repaired pallet to a new pallet the cost was $5.25 more but each of the 90 boxes was $0.10 lower cost than the original double wall box. Therefore the net savings per unit load was $3.75.
Unit load design is the future, and it has arrived. Pallet providers are the key to implementing these supply chain cost savings for their customers. You need to learn about how to take advantage of these tools.
Editor’s Note: The Pallet Profile and Recycle Record market reports are partnering with White & Co. to offer free basic courses on unit load design and the use of Best Load software. These will be presented in three webinar sessions held in August. See the ad on page 37 for more information or call 800-805-0263 to register. You can also email chailleb@gmail.com and type “Unit Load Webinar” in the subject line to register. To learn more about Best Load™ software go to www.whiteandcompany.net or email techsupport@bestloadpackaging.com.
