November-December 2016

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A ccording to the "Uniform Standard for Wood Pallets," pallet performance is based on three factors: strength, stiffness, and durability, which is why all three are included in the Pallet Design System™ (PDS) analysis. While strength and stiffness contribute to using materials most efficiently, the durability analysis helps to design a longer lasting pallet. The durability of a pallet is particularly important because a damaged or broken pallet cannot – despite its original strength, stiffness, or load carrying capacity – safely support or protect the product on the pallet. A better understanding of the durability analysis can help you provide your customers with pallets that sufficiently perform in the unit load handling environment over a longer period of time. Pallets sustain damage as they interact with handling equipment and are transported. The durability analysis in PDS simulates how a pallet will resist this damage, providing either an estimation of overall lifetime or a damage rate, meaning damage sustained per pallet usage. It is partially based on the FasTrack Handling Cycle at Virginia Tech's Center for Packaging and Unit Load Design, which is a physical simulation of pallet interactions and movements within the unit load handling environment. Durability in Design, Extending the Life of a Pallet 1 The properties of the chosen material for construction – Material properties include the selected wood species and grade of lumber. Denser, stronger species with fewer lumber characteristics (knots, wane, etc.) tend to exhibit better resistance to component breakage. 2 The strength of the connection between pallet components – Using fasteners with improved withdrawal properties, as well as increasing the number of fasteners per connection, can prevent pallet components from becoming dislodged. (This is a significant reason for the inclusion of fastener properties in PDS). 3 The design of the pallet – Thicker, wider components are more damage resistant than thinner, smaller components. Furthermore, design aspects like butting a lead deckboards with back-up deckboards can anchor the lead board so it does not become dislodged. Damage of wood pallets occurs either through component breakage or becoming dislodged from the pallet, so both must be considered when designing for improved durability. Breakage relates to material properties where component separation relates to connection strength. The design of the pallet may contribute to both forms of damage. When designing a pallet, if you enhance the material properties and see no improvement in damage resistance, then the connection strength is the limiting factor. The converse is also true: improving the connection strength with no observed improvement in durability means that the component strength is the limit factor. For more information on the Pallet Design System™ (PDS), please visit or phone: 703-519-6104. The ability of a pallet to resist damage is the function of three factors:

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