How Flow Rail Systems Improve Drive-In Racks
Reduced chances of rack damage and less time spent pulling into and out of rack structure
Drive-in rack is one of the best high-density pallet storage methods available, but it’s always had some drawbacks:
- Forklift damage within the lane is always a possibility as drivers must drive in, then back out inside the rack structure
- Since there must be driving space, drive-in racks lack lateral braces, which make them somewhat more vulnerable to collapse if struck
- Driving into and out of that rack structure also takes time
- Drive-in racks allow you to store only one SKU per bay
- Drive-in structures are typically 30 to 40% empty at any given time
Now there is a way to get the benefits of drive-in rack – dense storage through deep lanes – without the dangers inherent with driving into the rack space.
What’s the problem with drive-in rack?
Really, nothing, if it fits your needs. We have plenty of customers who use it, and are completely satisfied. When you don’t have a need for significant inventory rotation or a higher degree of flexibility, it’s great. Flow rails aren’t a competitive product, but one that makes drive-in more flexible, faster, and safer. How?
Drive-in rack storage is a dense storage system. It’s deep because the forklift drives into the rack lanes to place and retrieve pallets. You specify it because it has very high storage density.
The topmost bays are filled first, then the next one down, until finally the floor level is filled. Only one sku per lane can be stored because inner and upper pallets can’t be reached until the lower levels and front facing levels are cleared in a first in, last out system.
A lack of flexibility
That also means that lower levels of storage remain empty while intermediate or top levels are full, so that a forklift can access those pallets on the upper levels. Drive in isn’t typically used in applications where stock rotations and inventory flexibility are important due to these limitations. With standard drive-in, you must empty top tiers, placing new stock on upper levels as you work your way down, then put the old stock from the top tiers down on the floor level. You can’t mix SKUs or product runs because you have to empty the lower levels before you can access the upper levels.
Above, left: typical picking situation for drive-in racks. Each bay must store the same SKU, while the lift truck must circulate through the rack structure. Right: with Flow Rail, the voids are all moved backwards to the rear of the rack structure. Forklifts simply pick from the front, as they would in a pushback application.
Introduction to Flow Rail
Chain driven pallet motion without the need to drive into the pallet lane is the latest innovation in dense pallet storage. You can now store pallets up to 10 deep within each lane and never enter the lane itself beyond the forks. Just place the front edge of the pallet onto the front edge of the flow-rail and push until the front of the pallet is even with the front of the rack. Since the rails aren’t sloped, you lose no vertical space due to pitch.
The pallets ride on a chain that has small cleats to create friction between the pallet and the chain surface, thereby holding the pallet in place until it is removed by a fork truck. This cleated chain rolls inside a track and moves all the pallets at the same time forward or back, depending on whether the fork truck is removing or putting in a pallet.
Multiple SKU’s in the same bay
With the Flow Rail system, you access any level of storage you like, whenever you want. Store more than one sku per lane vertically and not worry about rotation issues. Place product runs in separate levels or lanes. It’s up to you. The first-in, last-out sequencing is still there, but you have much more flexibility – and improved density – because you can store a different SKU in each lane (the top lane can have a different SKU than the bottom or middle level). You don’t have to wait until upper levels are full before you can fill or pick lower levels. Add or remove pallets from each level as you please.
Safety, density, and time
When you retrofit drive-in rack with flow-rail, you get a triple benefit – improved safety, improved storage density, and significant time savings. Far fewer bent rack uprights, less chance of taking down an entire rack system because of a collision within the racking – that’s good. Fewer injury claims and less ruined inventory – that’s great.
Besides safety benefits, look at the storage density you achieve. Up to 20% more storage slots are filled simply because you don’t have to hold bays open in order to access upper levels. Even higher density can be achieved if you reduce the space between uprights, reclaiming space needed for the forklift width and maneuvering space. You may be able to actually add storage lanes to your existing footprint. Additionally, you can add up to 4 times the number of sku’s in the same space.
Oh, and time? Let’s just say, you’ll get a lot more productivity out of your forklift crews. Flow-Rail reduces load/unload time by 75% simply by not spending time driving in and out of the rack space. Instead, you’re always working at the edge. The pallets are always available without moving into the rack itself.
Also, Flow Rail makes more use of your space. Due to the way it must be loaded and unloaded, drive in racks are typically 40% empty. That drops to 15% with flow rail because each lane can be picked and restocked independently.
If you need to utilize more of the storage cube you have, improve safety, or save time in your drive-in rack area, consider retro-fitting with flow-rail.
This article is part of a series of articles on Flow Rail. Click on a link below to view one of the other articles.
- How Flow Rail Systems Improve Drive-In Racks
- How Flow Rail Helps Reclaim Storage Space In Push-Back Rack
- High Density Pallet Storage Racks: Comparing Pushback, Drive-In, and Flow Rail
Scott Stone is Cisco-Eagle's Vice President of Marketing with more than thirty years of experience in material handling, warehousing and industrial operations. His work is published in multiple industry journals an websites on a variety of warehousing topics. He writes about automation, warehousing, safety, manufacturing and other areas of concern for industrial operations and those who operate them.