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Efficient Pallet Storage in Industrial Warehouse and Distribution Space

In order to optimize productivity and profitability of your warehouse, consider product size, the available area, and the method of product retrieval.

Q1 2017
After you’ve selected a facility that will meet your long-term needs for growth, you need to meet with storage professionals to address how that new space is utilized. When assessing your needs, you will need to determine if your operation is pallet in/pallet out, pallet in/case out, or case in/case out. The same principles apply whether you’re storing hand-loaded case goods, pallets, or a mix of both, but for purposes of this article we’ll focus primarily on pallet storage.

Product Size
Product size is the first factor to consider when determining rack requirements. The space is best utilized if you store your products by common sizes, but you may not be able to do that if your warehouse management system doesn’t allow for random location of products. Ideally, when designing the system, it’s best to be able to store any item anywhere, with a focus on keeping the fastest-moving items closest to the outgoing door to maximize productivity.

The most important issue is determining the total number of pallets to be stored and the percentage of pallets for each sku (stock keeping unit) including an allowance for growth. Your growth projection should fall just short of the length of a lease, which gives you extra time to plan for additional growth or a move to a larger facility. The 80/20 rule will help determine the amount of working inventory on hand and where to store your most active items; they should be closest to the shipping/packing area to minimize travel time, walking, searching, and picker dwell-time functions.

Product/pallet sizes and weights, including product overhang, are another factor to consider. Typical grocery pallet sizes are 40"W x 48"D x 54"H depending on the type of product stored with an average weight of about 2,400 lbs. If you don’t address product overhang or pallet heights, significant product damage may result from the pallets being too tightly packed in, thereby affecting profitability. If you want the ability to store any pallet in any location, then you must design the system to store the highest pallet, including a minimum of 6" of “liftoff” for the lift truck to pick the pallet out of each slot.

The best way to make use of the cube is to store common-sized items together; however, this may not be the best method if your operation has a wide breadth of skus requiring multiple pick faces. Whether you store products numerically, alphanumerically, by size, or in random order, again, focus on storing the fastest-moving 20 percent of your items closest to the shipping/packaging point for optimal productivity.

The number of orders picked per day and the number of people picking orders and their functions help to determine the area you’ll need for checking in, processing, and staging for outbound shipping. Batch picking common items for several orders saves time and labor, but you must be able to sort and merge the orders in shipping to ensure accuracy. If you’re able to pick directly to shipping cartons, that eliminates a step in the order-picking process and might enable you to get product out the door faster. This, in turn, also helps to determine how often to replenish your storage system. Cross-docking your fastest moving products is the best way to avoid excess handling of fast-moving items and product damage. You simply locate fast-moving items close to the shipping area, perform check-in functions, and leave the product sorted by order for outgoing shipment.

Available Area
The area available is the next factor to consider when configuring your warehouse to store your goods most efficiently. Always design the rack system around the building and not the lift equipment because the racks will always outlast the trucks. Position all the rows of rack in the same direction because you will lose storage space trying to compensate for cross aisles, and don't let the building columns manage you. Wherever possible, locate building columns inside the rack, which affords them better protection from damage by lift trucks. You need to take note of the clear height to the bottom of the building joists and obstructions like HVAC units, lighting, sprinkler pipes, and gas lines because that lessens the net pallet count and will affect your bottom line. The height from the floor to the TOP of the sprinkler heads should be measured in several locations in the area because the top of your loads MUST be 18" below the sprinklers to meet local building codes. Lastly, the location of the shipping and receiving dock doors in relation to the storage area will ensure that there is proper flow for inbound product and check-in areas, and the proper amount of staging for outbound items.

Method of Retrieval
The method of retrieval is the last factor to consider in the utilization of your storage space. If you’re reconfiguring your space to get more capacity in the existing space, consider upgrading to vehicles with newer technology, higher capacity, and greater lift heights. Financing the equipment enables you to upgrade at any time. You should also determine whether you want your lift equipment to serve the dual purpose of loading/unloading trucks and entering the rack system, with the type of lift equipment selected depending on the desired output of your operation.

Standard electric or propane sit-down lift trucks generally require a 12' clear aisle to perform right-angle stacking functions. These versatile vehicles enable you to load/unload trucks and travel in and out of your facility, but wider aisle requirements reduce the amount of pallets stored in the warehouse. Stand-up reach trucks will cut your aisle requirements down to 8'6" to 9'6" and will generally increase your building capacity by 25 percent with a throughput increase of 25 percent over sit-down vehicles, but they cannot be used to load or unload trucks. Deep-reach trucks will generally give you a 35 percent increase in capacity with a 9' to 10' aisle and a 25 percent increase in throughput, but you won’t be able to load or unload trucks with them as well, so you’ll need to utilize electric jacks or sit-down vehicles for that function.

Very narrow aisle (VNA) turret trucks or swing reach trucks operate in aisles of about 5' to 7’, but give you 40 to 50 percent more pallet positions over standard lift trucks and 25 to 30 percent over reach trucks. They are captive to the system and cannot load or unload trailers, so you’ll need to supplement your material-handling fleet with electric or standard sit-down trucks or pallet jacks to perform those tasks. The savings in square footage, labor, and throughput provide great justification if you have ceilings greater than 25', but you must certainly purchase multiple vehicles because the system cannot be accessed by anything other than a VNA truck.

VNA hybrid lift trucks with articulating masts operate in 5' to 7' aisles and give you 40 to 50 percent more pallet positions than conventional sit-down trucks, but the great feature of these vehicles is that they can be used to load or unload trailers and move loads directly from trailers into the rack system. That feature alone justifies the use of these vehicles in any operation regardless of ceiling height; they are very commonly used in any operation because of their versatility.

There are many other factors to consider in looking at your space requirements including rent per square foot, taxes, availability of skilled/unskilled labor, insurance, and choosing the right storage system for your needs, but the above information helps to formulate the overall plan for your business.

In order to make the best of use of your warehouse, consider product size, the available area, and the method of product retrieval.

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