What ‘s an Optimal Performance Level?
Every warehouse is a little bit different and may require a somewhat different approach to maximize its storage density and/or efficiency of product movement.
Many warehouses that exceed around 85 percent of their storage capacity begin to feel a pinch on the productivity level. Docks and aisles may even begin to be crowded with “extra” pallets, and pallets carrying one kind of product may end up mixed in with those of another sort where this is not optimal space management.
Warehouse Storage Changes
Many times, changing the aisle width can help to save space or to increase productivity. This may entail, however, a change of pallet size or of pallet moving equipment. One will have to study out whether a need exists for forklifts to share a lane, turn sideways, or turn all the way around.
The wider aisles will make it easier to rapidly rotate stock and ship in or out new inventory, but narrower aisles will save storage space. Most warehouses in the U.S. use narrow lanes (108 to 132 inches), which allow two vehicles to pass each other. However, in some instances, very narrow lanes (72 to 78 inches) will help to increase storage density sufficiently that they will more than “pay for” any lost time due to more constricted aisles.
Warehouse Racking Systems
Changing one’s racking system is the second main way to increase a warehouse’s storage capacity. The first thing to do is simply to see if you can increase the rack height. Remember that fire code requires some top clearance space and of course that the forklift machine needs to be able to reach that high!
Next, survey the warehouse’s pallets to see if there are major gaps between pallets when you come to a new storage space (looking at the racks vertically). If the space is more than four to six inches, that is wasted space. You need that six inches to allow the fork driver to lift and move the pallets, but anything more and you should readjust the horizontal beams to create more space. However, also pay attention to the load limits of the racks – an overloaded rack is illegal and dangerous.
Common Pallet Rack Systems
The most common racking system is single deep selective. Post and beam racks are used, and there is an aisle between each row of racks. This system is not as dense as some others, but it is very versatile and low cost. Double-deep racks place two single-deep rack rows back to back. This saves valuable space, but does require electric reach trucks to manage the pallets in the back row. Floor level is often used for frequent in and out items, while higher up is used for longer-lasting reserve stock.
Push-back racks can be up to six pallets deep, amounting to “storage lanes” rather than simply depositories. There is a slight incline across the racks so that pallets pushed up the “hill” will by force of gravity slide back down as the front pallet is removed.
The price value of this system is quite good considering the balance it brings between product density and efficiency of use. Only warehouses in which full pallets are moved in and out can use a push-back system effectively, however. There are many other racking systems to choose from as well, and each warehouse must be analyzed to determine the best way to save space.