How to Optimization Pallet Storage and Picking

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World-Class Warehousing and Material Handling

is created by the removal of a load, a pallet opening is immediately available in single-deep racking. Also, because racking is supporting every load, stacking height is not limited by the stackability and/or crushability of the loads, and multiple SKUs can be stacked in the same vertical column of storage space. Loads do not need to be stackable and may be of varying heights and widths. In instances where the load depth is highly variable, it may be necessary to provide load supports or decking. The major advantage of single-deep racks is the full accessibility to all unit loads. The major disadvantage is the amount of space devoted to aisles—typically 50 to 60 percent of the available floor space. As a result, in cases where three or more pallets of an SKU are on hand, a storage method that houses at least two pallets in a facing perpendicular to the storage aisle may be preferable (Figures 5.13 and 5.13). Selective pallet racks might be considered to be the “benchmark” storage mode, against which other systems may be compared for advantages and disadvantages. Most storage systems benefit from the use of at least some selective pallet racks for SKUs whose storage requirements are less than three to five pallet loads. Double-Deep Pallet Racks Double-deep pallet racks are merely selective racks that are two pallet positions deep (Figure 5.15). The advantage of two-deep rack facings (perpendicular to the aisle) is that fewer aisles are needed. In most cases, a 50 percent aisle space savings is achieved versus single-deep selective racks. However, we cannot assume that a 50 percent true space savings will be achieved because we can only anticipate a 70 to 75 percent utilization of the available openings (due to honeycombing). (However, 80 to 85 percent utilization is common for single-deep racking.) Double-deep racks are typically used when the storage requirement for an SKU is five pallets or greater and when product is received and picked frequently in multiples of two pallets. (Assigning SKUs with only

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