Drive-In & Drive-Through Rack
Traditional pallet rack is a great solution for many warehouses, but if you have a lot of inventory that shifts on a regular basis,
drive in or drive through rack is a storage solution you may want to consider. While traditional static rack storage allows for many
rows of pallet racking with aisles between the individual rows, drive in and drive thru racking allows for a much denser arrangement
of your stored product. Both drive-in and drive through rack systems allow more efficient use of available space than traditional
multi-aisle selective racks systems. In fact, when compared to a conventional selective rack system, the same amount of storage
can be acheived with a high density drive in or drive thru system in 80% less space.
High density storage racks work by utilizing standard pallet rack uprights in conjunction with rail beams or more simply, rails to
store the pallet loads in a very dense configuration. The key difference between these racks and selective pallet racks is that the
forklift truck operates inside of the rack itself and there are no specified lanes between the rows. The forklifts enter into the
individual bays of the rack and the bays themselves can be as long or as short as needed.
Drive in rack and Drive through rack systems decrease storage and retrieval time while increasing efficiency and productivity among
workers. Not only do they benefit your operations, they can also decrease your bottom line by giving you more storage room per dollar
spent on racking. Because these racks create a more uniform load in a confined storage area, your forklift operators working in the
system become more skillful drivers. In addition to these benefits, consider this - drive-in & drive-thru systems are very energy
efficient. Since the product is so densly loaded in this type of system, there is less air to be heated or cooled between your pallets
and your forklifts don't need to drive as far to pick or place loads thereby using less fuel.
Pallet Rack/Drive-In Rack Comparison
Clearly, Drive-in or Drive-Through is not for everybody however, it is exceptionally good at storing large quantities of palletized
materials in a smaller space than would be afforded by selective pallet rack (see figure 6).
Types of High-Density Storage Rack
Within the class of drive-in or drive-through racks are several notable configurations - most commonly defined by the length of
storage time and ease of retrieval needed for the product being stored (see figure 7).
One Way Drive In - Last in First Out (LIFO)
Material is both stored and retrieved from the same side (entry point) in several aisles. For this reason, the first material put in
this system is the last to come out. This works well where shelf life is at a minimum or not a major concern. This system also works
well in cold storage environments or warehouse freezers.
Two-Way Drive In - Multi First-In Last Out System
Arranging drive-in to be enterable from two sides allows for maximum space usage and easy product accessability from two seperate sides.
Drive-Thru - First in First Out (FIFO)
Free access from both sides allows materials to be stored from one end and retrieved from the other. With this capability, a first in
first out storage arrangement is made possible. This system is used where there is expiration dated material or wherever shelf life is
of major concern.
A push-back racking system can be a great option when you're tight on space. In a push back rack system, the pallets each sit in a
tray that rides along rails in the rack frame itself. The push back rails are supported on an incline and gravity moves the trays along
the rails towards the front of the rack. From the front, the loads are both picked and deposited while the back of the rack remains
closed. When a load is deposited to the front of the rack, it will "push back" the previosuly placed load, thus decreasing picking
times but keeping the number of picking faces to choose from high.
Push-back racks can store multiple sized pallets up to six deep and four high making push-back rack a very efficient LIFO (last in,
first out) system. This type of dynamic storage system allows you to have all the benefits of a high-density storage system without
the drawbacks of a drive-in system. Let's look at this further.
With a typical high-density drive-in system, each bay will typically be filled same type of product. That way, when retrieving
products one need only go to that 'pick-face' to get any one item. If dissimilar items were to be placed in the same bay that entire bay
may potentially need to be unloaded to get at the needed product, thus wasting a large amount of time and resources. However, with a
pushback system many different products can be placed in lanes within the same bay allowing for a larger quantity of pick faces.
With each individual lane being a seperate product, those products will still be accessible without first unloading the rack.
Pallet Flow Rails
Similar in concept to pushback rack is a pallet flow system. The pallets move from back to front and as they are removed from the
rack, the next in line takes the previous pallet's place. Unlike pushback rack however, the rack is usually loaded from the back
and picked from the front.
Almost any static pallet rack system can be retrofitted to be a more efficient dynamic storage system
because the pallet flow rails drop into place using the existing racking components as their support structure. Lanes
of pallet flor rails usually have built-in 'brakes' that work to slow the pallets to a smooth gentle pace as they glide down the lane.
One of the biggest strengths of pallet flow rails over pushback is that flow rails will allow a longer lane. For example, while pushback
may be able to store pallets 5 deep, a pallet flow system will allow as many as 10-15 pallets deep.
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