Pallet Storage, Picking, and Slotting Optimization

1. Advantages of Pallet Flow Racks

The design of pallet flow racks offers significant operational advantages that make them an appropriate rack selection for some fairly common warehousing scenarios. Those operational advantages include (1) first-in-first-out product rotation, (2) reduced vehicle congestion, (3) increased productivity, and (4) excellent storage density (for products with a large number of pallets on hand).

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1.1 First-In, First-Out (FIFO). This system naturally enforces a FIFO inventory flow because the first pallet loaded into a lane is always the first one available to be picked. For products with expiration dates, like food or pharmaceuticals, or those needing strict lot control, this is a critical inventory management feature as it prevents spoilage and facilitates product rotation.

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1.2 Reduced Congestion. Because restocking (loading) and retrieval (picking) happen in different aisles, there is far less traffic congestion at either the restocking or picking face. Forklifts aren't competing for space on the same side of the rack, which is especially important for high turnover products.

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1.3 Improved Productivity. The rack itself moves the pallet into the picking position. Since manual labor is not required for this internal movement, operators can work more efficiently, leading to improved overall productivity.

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1.4 Excellent Storage Density. Pallet flow rack lanes are typically three or more pallets deep and three or more levels tall yielding excellent storage density within the rack structure as long as the products assigned to the rack have a high number of pallets on hand.

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1.5 Conventional Vehicle Access. Pallet flow rack does not require a special handling vehicle or attachment to move pallets into or retrieve pallets from the rack.

 

2. Disadvantages of Pallet Flow Racks

Pallet flow racks are a specialized solution with disadvantages that must be weighed against their benefits. The primary disadvantages are the high cost of the rack structure and the loss of floor space stemming from the need for the two aisle sides for every storage lane.

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2.1 Expensive Investment. The pallet conveyor or air flow mechanism installed in the rack yields an investment cost of a few to several hundred dollars per pallet position.

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2.2 Two-Sided Floorspace Requirement. Because the racks require aisle access on both the front and the back, they take up more floor space than systems that only need a single aisle for loading and unloading.

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2.3 High Maintenance. In order to maintain the safe and efficient movement of pallets within the pallet flow rack, the conveyance within the rack itself must be diligently maintained.

 

3. Pallet Flow Rack GOTCHAs

RightChain has many clients with beneficial installations of pallet flow rack. Along the way in helping those clients we have come across a few “gotchas” or pot holes in the road to successful implementations of pallet flow rack; namely (1) poor pallet quality, (2) sub-optimal slope design, and (3) honeycombing.

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3.1 Poor Pallet Quality. Damaged or weak pallets may not move reliably or consistently enough within the pallet flow rack structure. Using pallets of sufficient quality is critical to ensure they move through the system reliably, safely, and consistently without causing jams or damage.

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3.2 Sub-Optimal Slope Design. The optimization of the slope of the racking within the pallet flow rack system is critical to insure efficient and safe pallet movement without losing excess storage capacity due to the slope itself.

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3.3 Honeycombing. Pallet flow lanes are best suited for products with several pallets on hand—typically three or more; thereby avoiding an inefficiency known as the "honeycombing effect." Honeycombing occurs when a deep storage lane is not fully utilized. For example, if you only store one or two pallets in a lane that is ten pallets deep, the lane utilization is extremely low because the back portion of the rack remains empty and unusable.

 

4. Best Use Case for Pallet Flow Racks

In all our work with pallet storage systems selection and optimization, in “words”, the best uses for pallet flow rack are for high turnover products with three or more pallets that require first-in-first-out (FIFO) rotation in facilities where storage space (occupancy) is fairly expensive, justifying the higher initial investment in a dense and efficient system.

 

5. Summary

In summary, pallet flow rack is a dynamic storage system designed to provide automatic First-In, First-Out inventory rotation via in-rack pallet conveyance. By separating the loading (restocking) and picking (retrieval) aisles, pallet flow rack excels at reducing congestion and improving productivity for high-volume products. While not the right fit for every situation, it is a powerful and specialized tool in the toolkit of modern warehousing.

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Pallets are conveyed from the back of the rack to the front via pallet roller conveyor or pockets of air. Pallets are loaded (restocked) into the rack at the back of the rack structure and retrieved (picked) from the front of the rack structure.

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Advantages

• First-In-First-Out (FIFO) Inventory Rotation

• Reduced Vehicle Congestion for High Turnover Products

• Improved Handling Productivity

• Excellent Storage Density for High Inventory Products

 

Disadvantages

• Expensive Initial Investment

• Double Aisle Sides

• High Maintenance Requirement

 

Gotchas

• Poor Pallet Quality

• Sub-Optimal Slope Design

• Honeycombing

 

Best Use Cases

High turnover products with three or more pallets that require first-in-first-out (FIFO) rotation in facilities where storage space (occupancy) is fairly expensive, justifying the higher initial investment in a dense and efficient system.