Pallet AS/RS

A crane or shuttle runs in a narrow aisle between tall racks, lifts a pallet by itself and puts it into a free place up to the roof. When the pallet is needed, it takes it out again and delivers it to the end of the aisle. A lot of pallets fit into a small building with nobody driving in the aisles; this is called a pallet AS/RS.

It comes in several forms. A crane runs in each aisle; a pallet shuttle moves pallets within deep lanes (see shuttle system); and in a high-bay warehouse the racks are also part of the building structure.

Because pallets are stored by machine, goods in and goods out need a handover point: conveyors or trucks at the aisle end, with scanning and a check of the pallet's size and condition. A pallet that fails the check has to be dealt with before the machine will accept it.

When it pays off

It pays off for large volumes of pallets in a steady flow, where land or building cost is high or the space is cold or frozen and every cubic metre costs money to keep that way, and where labour is expensive. It pays off less with few pallets, mixed pallet quality, or a flow that is likely to change. Compare it with narrow-aisle trucks and shuttle systems, which also use height, before choosing.

What the warehouse system does with it

The warehouse system sends store and retrieve tasks per pallet, with the pallet's identity and, for retrieval, the destination such as a dock door or a station. The machine controller confirms each move and reports faults and the place used. Because the machine only accepts pallets that pass the entry check, the WMS or the control layer often reads size and weight data on the way in and reports the result back.

Who makes it

Daifuku, Dambach Lagersysteme, Jungheinrich, Knapp, Mecalux, Stöcklin

In alphabetical order. Not a ranking or a recommendation.