Question from Will: We’re experiencing load failures at random times throughout the year and across different shipping methods. We adjust our load containment standard, everything seems fine, and then suddenly we have more failures. What could be causing this, and how do we prevent it?
Hi Will, great question! As you’ve experienced, many variables affect load containment. In fact, successful containment is much like building a skyscraper. You need a solid foundation (bedrock vs. quicksand), each floor must bear the weight of the floors above it (internal forces), and the structure must withstand the effects of wind (external force). The next time you look at a pallet sitting on your shipping dock, you will see the similarities.
Let’s start with the pallet, which must provide a solid foundation for the load. Pallets that are poorly constructed (stringers with knots, too few deck boards, cracked or twisted lumber, or insufficient or improper nails (yes, there are special pallet nails that should be used) compromise stability. Pallet materials and construction must be sufficient to support the weight of your load and handle the forces applied during transportation. I was talking with a customer last week that told me they reject about 20% of their CHEP pallets due to damage. Many companies skip proper inspection and simply use whatever pallets they have on hand instead of making sure the pallets they use will meet the rigors of transportation.
Next, consider the load itself. Each layer is like a floor of a skyscraper. The stacking pattern must create a stable platform for the next layer. That means the design of the primary packaging is a major consideration. If you are packaging solid cubes, and their layer footprint matches the dimensions of the pallet, you are golden. However, I seldom see a load like that. Most have inherent challenges. Folding cartons that crush easily, plastic bottles, or products stacked several inches inboard from the pallet edge are examples of more challenging loads to contain.
Plastic bottles are an especially good example. Downgauging has drastically reduced their load bearing capacity, and to make matters worse, the weight from the layers above is concentrated on the cap, which has a much smaller surface area than the base of the bottle. In addition, when a load stops quickly after being in motion, the liquid maintains inertia which magnifies the applied force on an already weak bottle. Packaging always involves a compromise between consumer appeal and surviving the supply chain.
Now let’s look at some external factors, beginning with the weather. You were very astute to notice seasonal differences in load containment, and yes, it’s absolutely a thing! Corrugated tends to absorb moisture, so high humidity increases its moisture content. It is a factor often overlooked when sizing the corrugated for the load. As much as 40% of its strength may be lost as a result. So, great containment in January may lead to load failure in July.
Your method of shipment and how the trailer, container, or railcar is loaded also play major roles in establishing your containment standard. Ideally, the load pattern should allow little to no movement during transportation; something that’s rarely achieved. The weight and dimensions of the pallet dictate how the load is configured. Weight distribution must remain within the axle limits, which often results in unsupported gaps between pallets. Dunnage such as air bags will help stabilize the load by filling gaps, but they are expensive, inconvenient to use, and, when used incorrectly, make the situation worse!
If you ship full truckloads and load trailers at your own facility, you maintain significantly more control over load containment because the pallets remain untouched until delivery. This is NOT the case with Less Than Truckload (LTL) shipments. When shipping LTL, pallets are consolidated with others, unloaded at a terminal, staged, and reloaded on a trailer headed to the next terminal. This process repeats until they finally reach their destination. I’ve personally seen LTL shipments from Phoenix, AZ to Santa Rosa, CA where they were cross-docked eight times! That’s eight unloads and eight reloads. By the time your customer opens the trailer door at delivery, the pallets may be severely damaged, or the loads have collapsed. I will let you in on a little secret, the forklift drivers at these terminals are incentivized by throughput, not care. Gentle handling isn’t part of the formula.
The bottom line is that successful load containment comes from optimizing each factor that affects it. Pallet quality, packaging design, environmental conditions, shipping method, and load configuration. We have studied the physics of load containment and developed test equipment that can replicate the various forces a load may experience during transportation. This research led us to create patented stretch wrap technology that overcomes many of these challenges. Our goal is to bring a solution that is tailored to your specific needs.
Thanks for asking!
