Different products offer different challenges in this regard. For Ken Cozart, vice president of operations for Addison, TX-based Mattress Giant, moving 150-pound king-sized mattresses from a shelf offered its own unique challenges, as racking had to be strategically located as not to impede the turning radius of a forklift. “We need to get to the product quickly, and at the same time, make sure the forklift can easily navigate a 90-degree turn in a 12-foot, 6-inch aisle.”
TYPES TO CONSIDER
When choosing a rack storage system, here are some of the various types to consider
Pallet flow rack: With pallet flow rack, the pick face is always occupied since gravity rollers or tracks allow products on pallets to flow to the front of the pick face.
Since the lanes are slightly pitched and consist of gravity rollers or tracks, the pallet moves forward until slowed or stopped by a retarding device, physical stop or another pallet in front of it. When an operator removes pallets at the pick face, the remaining pallets accumulate forward.
Since pallet flow rack is the only dynamic rack system that offers a FIFO method of inventory management, this is beneficial when expirations are a consideration, as well as the risk of product obsolescence. Saddle Creek utilizes flow rack for high-velocity case or each picking, where FIFO rotation is critical, such as with health and beauty aids.
Drive-in/drive-thru rack: As the name implies, drive-in/drive-thru rack means that a forklift can travel inside a storage bay that is multiple pallet positions deep in order to place or retrieve a pallet. Often times, forklift drivers are guided into the bay through the guide rails on the floor and the pallet is placed on cantilevered arms or rails. Drive-in/drive-thru rack is typically used when space is limited and when there are many of the same type of products (SKUs) being stored
For Saddle Creek, drive-in/drive-thru was perfect for a number of its products. “We use drive-in/drive-thru when we have products that are fairly standard in weight and size, such as cases of canned beverages” says Single. “This allows us to store product as deep in the bay as possible.
This medium also requires experienced fork truck drivers. Since every pallet requires the truck to enter the storage structure, damage is more common than with other types of storage.
In designing a drive-in system, dimensions of the fork truck, including overall width and mast width, must be carefully considered.
Selective rack: Selective rack is the most popular and widely recognized bulk storage solution in industrial environments. It is also commonly referred to as static rack and as that name implies, there are no moving parts. Selective rack is an ideal solution for a warehouse that has a wide variety of products (SKUs). It offers direct access to all stored pallets, allowing warehouse operators the ability to handle one pallet without the need to move another. Selective rack also offers ease and simplicity with respect to inventory location and designation as each pallet position can be assigned a dedicated SKU for storage.
Selective rack was the ideal solution for the Mattress Giant warehouse, when it installed heavy-duty teardrop pallet racking with various load capacities to accommodate three-level storage. Level A stores heavier 150-pound mattresses, Level B houses all lighter framing and box springs, and Level C shelves all overstock and seasonal products.
Push back rack: Push back rack utilizes between two and six carts that nest within one another and travel by gravity to the first position of a lane when empty. A warehouse operator can drop a pallet on the first cart just as if he would with selective rack. In the event another pallet needs to be stored, the warehouse operator gently pushes the first product resting on a cart back, thereby making room to place the second pallet on the second cart. When an operator needs to retrieve a pallet, he lifts the first pallet in the lane and gravity forces the carts behind to move forward and present a new pallet to the first position in the lane.
This storage medium provides a LIFO method of inventory management similar to drive-in/drive-thru rack. The advantages of Push back rack are the increased density in storage, very similar to drive-in/drive-thru rack, but coupled with the ease of selecting the pallet at the pick face instead of driving into the racking system.