Double deep ASRS benefits

In a -25°C cold storage facility, you aren’t just storing pallets; you are paying to refrigerate air. Every square foot of empty aisle space in a traditional selective rack setup is a direct leak in your P&L. For high-volume food processors and cold chain operators, the “honeycombing” effect of standard racking is financially unsustainable. The Starack Double Deep system cuts your aisle count by 50%, compressing your frozen inventory into a tighter thermal envelope while maintaining the speed required for perishable logistics.

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The Economics of Frozen Air: Why Density Matters

In the cold chain and food, beverage (F&B) sectors, the primary cost driver beyond the initial build is the daily energy consumption required to maintain temperature. Standard single-deep selective racking offers 100% selectivity but requires an aisle for every single row of racks. This results in a warehouse where nearly 60% of the volume is air—air that you are paying thousands of dollars a month to cool.

The Double Deep Automated Pallet Warehouse addresses this specific thermal inefficiency. By storing two pallets deep from a single aisle access point, we effectively eliminate half of the aisles required in your facility.

This structural change delivers two physical outcomes:

Volumetric Compression: You can store the same 10,000 pallets in a building footprint that is 25-30% smaller. This significantly reduces the surface area of the roof and walls, where thermal transfer (heat gain) occurs.
Reduced Refrigeration Load: With less total cubic volume to cool and fewer aisles for cold air to escape during ingress/egress, the refrigeration load decreases. Our data indicates that shifting from single-deep to double-deep automation can lower energy costs per pallet by approximately 18-22%.

A Rack Clad structure maximizes vertical density, crucial for minimizing the footprint in expensive cold storage zones.

Structural Rigidity in Cryogenic Conditions

A common failure point in automated cold stores is the deformation of steel structures due to thermal contraction. When temperatures drop from an ambient installation temperature of +20°C to an operating temperature of -25°C, steel contracts. In welded structures, this creates internal stress points that can warp the guide rails.

For a stacker crane operating at 30 meters high, a rail deviation of just 5mm can cause the safety sensors to trigger an emergency stop, freezing your logistics flow.

Starack systems utilize a fully bolted structure using Q355 high-strength steel. Unlike welding, bolted connections provide the necessary micro-tolerances to absorb thermal contraction without distorting the verticality of the masts. This ensures that the ASRS stacker crane maintains its ±3mm positioning accuracy even in deep freeze environments, preventing the “ghost stoppages” that plague welded systems.

Balancing Selectivity with Throughput

Critics of high-density storage often point to “buried” inventory. In a Drive-In rack (which might be 10 pallets deep), retrieving the innermost pallet requires moving 9 others. This is a nightmare for FIFO (First-In, First-Out) management, which is non-negotiable for food products with expiration dates.

Double Deep ASRS offers the optimal compromise. You only ever have one pallet blocking another.

The Logic of the Telescopic Fork

The system utilizes a specialized telescopic fork on the stacker crane. When the WMS (Warehouse Management System) receives an order:

If the target pallet is in the front position, it is retrieved immediately (Time: ~45 seconds).
If the target pallet is in the rear position, the crane moves the front pallet to a temporary buffer location (typically an adjacent empty slot) and then retrieves the rear pallet.

While this “re-shuffling” adds a marginal amount of time compared to single-deep systems, the WMS algorithms optimize storage during off-peak hours. The system automatically rearranges pallets so that items with sooner expiration dates are moved to the front positions (Housekeeping Mode). This ensures that during peak shipping windows, the crane rarely needs to perform double moves, maintaining high throughput.

GSP-compliant buffering in a clean environment. The double-deep logic is managed entirely by software to ensure strict FIFO adherence.

Energy Regeneration: Turning Gravity into Electricity

In a high-bay warehouse, lifting a 1,000kg pallet of frozen beef to a height of 35 meters requires significant energy. However, lowering that pallet creates potential energy.

Starack systems are equipped with Regenerative Braking Units on the hoist motors. When the carriage lowers a heavy load, the motor acts as a generator. Instead of dissipating this energy as heat (which would then require more cooling to neutralize), the system converts the kinetic energy back into electricity. This power is fed back into the DC bus to power the horizontal travel motors or returned to the facility’s grid.

For a 24/7 cold storage operation, this feature alone can reduce the ASRS mechanical energy consumption by up to 30%, further improving the ROI of the automation investment.

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FAQ: Double Deep ASRS in Cold Chain

1. How does Double Deep ASRS handle strict FIFO requirements for perishable goods?
The WMS (Warehouse Management System) tracks the Batch ID and Expiration Date of every pallet. It directs the stacker crane to prioritize the removal of older stock. During low-activity periods, the system performs “housekeeping” cycles to reshuffle pallets, ensuring the oldest product is always in the front (accessible) position before the shift begins.

2. What happens if a pallet breaks or debris falls in the rear position?
Starack systems use profile scanning at the induction point to reject damaged pallets before they enter the system. Inside the rack, the telescopic forks have torque sensors. If resistance is met (due to debris or ice buildup), the system halts to prevent damage. Maintenance access is provided via the stacker crane’s maintenance cabin.

3. Can existing cold storage warehouses be retrofitted with this system?
Yes, provided the slab can bear the load. However, the most value is gained in “Rack Clad” buildings where the racking supports the roof and walls. For existing buildings (Brownfield), we often recommend replacing forklift aisles with ASRS to double the capacity without expanding the building shell.

4. Does the equipment function reliably at -30°C?
Standard equipment fails at these temperatures. Our cold chain configurations use specific low-temperature steel alloys, heated control cabinets for the PLCs, and special low-viscosity lubrication for gearboxes and bearings to prevent freezing and ensure smooth operation.

5. How does the throughput compare to a standard forklift operator?
A single double-mast stacker crane can perform 25-30 dual cycles (in + out) per hour. Unlike a forklift operator who requires breaks, moves slower in the cold due to PPE, and faces visibility issues with fog, the ASRS maintains this pace 24/7 with zero risk of racking damage or injury.