Pushback vs Drive-in Rack System
For many types of businesses, it’s essential to store inventory in a warehouse. This is an unavoidable truth that you are no doubt already familiar with. Warehousing allows companies to hold their inventory—which could be anything from teddy bears to wrenches—in a secure site where these products can be easily retrieved when necessary. Therefore, maintaining access to storage space of sufficient capacity is an all-important concern for a lot of companies. Without it, businesses can lose customers if they cannot accommodate a sudden surge of demand for a particular product—more than a few people will simply cancel an online order if they encounter the dreaded message “Temporarily Out of Stock.”
No business possesses unlimited resources, which means that warehouse managers must contend with the problem of maximizing storage space. In other words, how can a company fit as much inventory as possible inside a finite area? One solution that has proven highly effective—and widely adopted—over the years is pallet racking. The basic idea behind pallet racking is quite simple: Warehouse products are placed on a flat panel known as a pallet, usually (but not always) made of wood, which can be stacked on top of one another in columns supported by a metal rack structure. Pallet racking exists in a number of configurations, but two in particular have found favor among efficiency-minded warehouse managers: the pushback rack system and the drive-in rack system. Below we’ll take a closer look at these two warehousing systems and their respective benefits. First, however, we’ll examine standard pallet systems and the reasons why these traditional methods may be inadequate for your business.
Traditional pallet rack systems
In some cases, it’s possible to stack pallets directly on top of one another, without a supporting structure. This is called bulk stacking, and it’s a simple organizational method often seen in warehouses with low-volume inventory. It is inexpensive—there are no elaborate racking structures to purchase—but it also comes with a number of disadvantages. Anyone who has ever stacked boxes in a column is well aware that they can easily topple; also, it’s impossible to access anything other than the box on top of the stack. Conversely, pallet racking solves these problems by utilizing a structure that holds products securely in place and permits relatively easy access to them.
One of the most common of these systems, selective pallet racking uses a structure of beams, frames, and braces to arrange pallets along aisles. In this configuration, the pallets can be easily retrieved by a forklift that maneuvers through the aisles. This is a system used in many warehouses today, and there’s nothing wrong with it—provided that there’s no need to maximize floor space. With selective pallet racking, each slot holds one pallet and no more. This means that storage density is limited. As a result, some warehouses that employ standard pallet racking systems may find themselves running out of room.
Pushback and drive-in rack systems are recommended for warehouses in which optimal storage density is important.
What is a pushback rack system?
Pushback rack systems allow pallets to be stored deep while still enabling easy accessibility. In a typical pushback configuration, about five pallets rest in a row at a slight incline, with one facing the aisle and the others immediately behind the front-facing pallet. When the forklift removes the nearest pallet, gravity allows the others to gently slide forward until the nearest one fits into the same position that the removed pallet had just occupied. Restocking is essentially the same operation in reverse: The forklift simply pushes a pallet into the front-facing position, shoving the other pallets to the rear. The most recent pallet to be loaded onto the rack is the first one to be removed. This means that the pushback rack system is a Last In First Out (LIFO) inventory configuration. The loading and unloading functions both occur from the same position on the aisle.
So what are the advantages of this system? For one thing, it substantially increases storage density. Pallets can be stored deep without worry that the ones in the rear will be unreachable from the aisle. As a result, it's possible to configure the warehouse with fewer aisles than are needed for a typical pallet racking arrangement. Less aisle space equals more room for inventory.
What is a drive-in rack system?
Drive-in rack systems provide another way to maximize storage room in a warehouse. As with a pushback configuration, a drive-in system allows inventory to be stacked high and deep. The primary difference here is that the forklift operator loads and unloads pallets by driving into the storage bay. The operator fills the inventory space by placing pallets in a column at the rear of the bay, then building another column of pallets in front. The process continues until the bay is filled. This means that the oldest pallets can be found in the rear, making this another Last In First Out arrangement. When removing pallets, the forklift operator simply picks the topmost one from the column closest to the aisle, maneuvering into the storage area when needed.
Compared with the pushback style, the drive-in rack system allows even greater storage density—and far more than a traditional pallet layout ever could.
Which system is best?
Naturally, there is no universal answer to the question, as it all depends on the preferences and storage demands of the individual company, as well as the configuration of the warehouse itself. As LIFO systems, the pushback and drive-in configurations share the disadvantage of being generally unsuitable for perishable inventory (except those with distant expiration dates), as pallets at the rear may sit untouched for a long time. However, this may not be a relevant consideration in warehouses with high turnover.
As previously noted, the drive-in configuration is best when storage density is a paramount concern. It’s also easier to store large or irregularly shaped products with the drive-in system, and there’s also less chance of rack failure. But the pushback rack system has benefits that should not be ignored. For one thing, it speeds up the picking process because the forklift never leaves the aisle to grab a pallet. Likewise, restocking is a simpler and less time-consuming matter with a pushback system. The convenient design of the pushback systems also sharply reduces the likelihood of forklift accidents.
Which is more important—storage space or picking speed? Answering that question will help you decide which of these rack systems is best for your warehouse.