Pallet Flow Rack Design – 2 vs. 3-Rail Systems | Mallard Best Practices
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The advantages of pallet flow rack center squarely on improving warehouse productivity. Pallet flow optimizes space and order-picking productivity in high-density storage, case and layer-pick operations, cold storage, manufacturing, assembly, and so many more applications. However, there is one scenario when pallet flow isn’t productive… and that is when it’s under-designed for the inventory load. It’s imperative that each pallet flow system is configured to the inventory load and pallet specs.
Specs Critical to System Design:
- Loaded pallet weight
- Pallet dimensions
- Inventory dimensions
- Pallet style
- Pallet size
Choosing between wheeled or roller rails, how many rails, setting the pitch, and properly applying accessories are all decisions in the design and testing process based upon all of these specs. To help make the process easier, we’re offering our Best Practice Tips for choosing between a 2-rail or 3-rail flow design when configuring a pallet flow system.
Mallard Best Practices 2-Rail vs. 3-Rail Pallet Flow Lane Design
One of the most common mistakes we see is a system designed using 2 pallet flow rails instead of 3. In a 2-rail lane, pallets are supported under the outside pallet runners only and not in the center of the pallet. The design is sufficient for some applications but often ineffective for others. Not properly supporting the pallet load can ultimately result in additional system costs in terms of reduced productivity, worker injury, and repairs. It’s better to get the system right from the start.
2-Rails Under-Supported Load — Ineffective Operation
Consider 2-Rails If:
- Inventory is under 1500 lbs.
- Pallets are in good or excellent condition
- System is 2-3 pallets deep
- Loads are evenly distributed
2-Rail System Cautions:
- Underrated capacity (pallet loads too heavy)
- Less contact points can allow load to shift downlane
- Pallet stress can cause splintering, interfering with safe operation
- Pallets more likely to hang up in the lane due to fewer contact points
- Pallets can fall through on multi-level systems
Again, inventory specs are critical, as is pallet quality. With fewer contact points (pallet to rails), the pallets can shift left to right in the lane, causing them to arrive skewed at the pick face and therefore making extraction more challenging. Even worse, they can dislodge from the lane and fall. These are two main reasons we suggest 2-rail systems no deeper than 3 pallets.
Always be wary of inferior pallets in a pallet flow system, but even more so when the pallet is under stress and not adequately supported. Broken or splintered boards slow down productivity and are a warehouse safety hazard to address.
Also, good to note that 2-rail systems often perform better where wheels are staggered. Keeping the pallets flowing is challenging with fewer wheels, so we often see this design working most effectively. As always, we recommend testing the lane design before placing the order.
3-rails Properly Support Pallet Load
Better off with 3-rails if:
- 3+ pallets deep
- Pallet condition less than excellent
- Pallet load weight > 1500 lbs.
- System requires speed controllers
- Multi-level system
3-rail systems better distribute the pallet weight across the lane, reducing stress on the pallets and the wheeled rails to keep your pallet flowing. Speed controllers can be mounted in strategic points across the lane providing proper pallet control for both speed and tracking downlane. Faster, safer, and easier removal of the pallet comes from a pallet centered squarely in the lane at the pick face. Hang-ups and shifted pallets are not cost-effective, and neither is having to unload the system to go after a stuck pallet.
Remember, the most cost-effective pallet flow lane is the one that performs day in and day out… that pallet flow lane is the lane designed to handle its inventory. We can help you arrive at the best system design for your needs. Call the Mallard team to talk about pallet flow system design!
Check out two of our earlier blogs to see some real-life pallet flow applications gone wrong:
https://www.mallardmfg.com/pallet-flow-rack/buyer-beware-series-takes-on-skate-wheel-pallet-flow/
