Tips for Better Drive-In Rack Specifications, Operations and Safety
Get the most from your high-density storage system
When you need exceptionally high-density pallet storage, drive-in racks deliver space savings by eliminating forklift access lanes. They’re last-in, first-out storage ideal for stock that doesn’t need active inventory rotation and will be picked and used in a relatively fast manner. There are challenges to any storage system, of course. This guide should help you find ways to reduce the problems and operate your drive-in rack system more efficiently and safely.
Loading and unloading
Drive-in systems are loaded and unloaded from the front. To stow a pallet, the driver must enter the rack structure with an elevated load. The load must be in position above the highest rail when the driver enters the rack, and then driven into the farthest back storage position. This means your drivers must be more skilled to use drive-in systems than other types.
Don’t allow forklift drivers to store loads in the middle of the rack system rather than the very back pallet position. Ideally, your inventory will be slotted so that you can always fill a bay with pallets. If you can’t, you may want to consider a different storage strategy for that SKU. In the event of a mid-load pallet and new stock, drivers will be forced to move that pallet before they can finish replenishing the lane.
Don’t allow push-loading. This means that pallets should always be lifted, moved and set back onto the rails. Pushing places undue stress on your rack and can put people and stock in danger. Drive-in rails aren’t designed for pushing action. Always lift and move.
Beef up your induction points. Because entry into the rack system is probably the most common area for accidents and bumps, adding structural elements like beefier columns, flared entry rails, offset leg designs and heavy foot plates help protect your entry points. Anything you can add to protect and guide drivers into the bay is a good investment in safety and efficiency.
Slow it down. Train your drivers to slowly enter, drive and exit the structure. It’s easier to side-swipe a column or rail at higher speeds. Make sure people are gently lowering pallets onto the rails rather than dropping them; one damaged rail can cause plenty of delays and frustrations.
Add lighting: Because drivers will be entering a deep lane system with pallets stored overhead, visibility will be poor inside the rack. Ceiling mounted lights will be blocked. Add forklift lighting accessories to help drivers see as they store and retrieve pallets.
Consider depth vs. time when you design your system. Very deep configurations may be better as drive-through or double-entry. For instance, if you need to store 10+ pallets in a position, you can consider sacrificing space efficiency for loading/unloading speed by splitting the rack in the center and creating a double-side entry layout that lets drivers load and unload from two sides. Reducing the forklift travel distance inside the rack structure makes it faster to store or retrieve a pallet at the cost of adding extra access aisles. Shorter distances in the structure reduce the chance of hitting a column or rail.
This is why many systems that reach the 10-deep threshold are better done as back-to-back 5-deep systems.
Specify contrasting rail and upright colors. A bright rail color (yellow or orange) set against blue or green uprights helps drivers see the rails better as they enter them.
Does a pallet shuttle or ASRS system make sense? The majority of LIFO (last-in, first-out) applications work well with drive-in systems. However, for some high-volume needs, a pallet shuttle system may be the solution. While any decision of that magnitude should be analyzed by engineers and professional warehouse designers, the article below is a good overview of the systems and how they compare. Pallet shuttles let you access the load FIFO or LIFO, and can be designed for much deeper storage than drive-in systems.
Above: a damaged pallet stack inside a drive-in aisle.
Only use the right pallet size and type: Because drive-in systems are built for a specific pallet size and type, you should never accept pallets that aren’t suited for the rack system.
- Ill-fitting pallets can slide, fall or crack.
- Make sure your pallets are in good shape before loading them into the rack. Dealing with a broken pallet and spilled load inside a rack system is difficult and can be dangerous.
- You can engineer more versatility into a drive-in system with wider pallet rails, but that won’t protect your system from being loaded with the wrong pallets.
- If you need to store multiple pallet sizes, separate the various rack structures from each other, clearly mark them and train workers about the right pallet for each rack area.
- Color-code pallets and rack structure to reduce mis-loads if you have more than one pallet type in a shared space. If you receive pallets from outside your organization and they don’t fit your system, work with suppliers to specify the right pallets in advance, or re-palletize before putaway.
The importance of the right pallets, in good shape, can’t be overstated when it comes to drive-in safety and operations.
Drive-in racks are unique because they are the only dynamic rack system that requires forklifts to enter the system and navigate between the uprights. Most systems are designed for a specific size and type of forklift. Make certain that you don’t use the wrong forklift for your rack system.
- Your rack’s openings must match the width of your forklifts. The forklifts must have adequate side-to-side clearance to reduce the chances of a collision with uprights or rails. The forklift must be narrow enough not to drive over your base plates.
- Use only counterbalanced forklifts with drive-in systems. Stackers and straddle trucks should never be used with a drive-in rack, nor should any forklift that has outriggers. Any truck or attachment that is wider than the openings cannot be used.
- Drivers’ cages and roll bars should be lower than the first rail level of the rack system to avoid contact with rails.
Forklift-rack compatibility is critical, so understanding both types of equipment is important to success.
- Case Study: Frozen Storage Rack System for Zero Mountain
- Horizontal Flow Rail Systems
- Download Cisco-Eagle’s Pallet Rack Guidebook
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.