Glossary
AS/RS crane
Automated high-bay storage and retrieval machine
An AS/RS crane is an automated machine that travels along the aisle of a high-bay warehouse to deposit and retrieve loads, with no human entering the aisle. It is also known as a stacker crane or an automated storage and retrieval system.
How it is built
A guided mast travels at floor and roof level along a narrow aisle between two runs of racking. It moves horizontally and vertically at the same time, picks up a load with a telescopic fork or a gripper, and places it in its location. At the ends of the aisle, conveyors handle load entry and exit. Management software drives locations and movements: in an automated warehouse nobody knows where an item physically sits, and nobody needs to. Versions range from mini-load machines handling bins of a few kilos to heavy pallet cranes in warehouses thirty metres high.
What it really delivers
Density first. By removing human traffic from the aisles, aisle widths drop below a metre and a half and heights go far beyond what a forklift reaches. Per square metre of floor, the gain is considerable — and that is often the real reason for the investment, well ahead of productivity. Inventory reliability next. With every movement recorded, discrepancies become marginal. And the removal of strenuous handling at height, with the risks that go with it.
When it is out of proportion
The investment runs into hundreds of thousands of euros, often beyond, building included. It is only justified by high, stable and durable volumes. Rigidity is the least anticipated counterpart. The warehouse is sized for one load format and one throughput. Changing packaging, doubling the number of items or relaying out the area becomes a heavy project, where racking can be dismantled in a day. Finally, it is a single point of failure: when the crane stops, the stock is not accessible at all. Manual recovery, in a metre-and-a-half aisle twenty metres up, is not a serious option. For many workshops the real need — gaining space and sparing operators the search — is met differently: a flow rack that densifies and enforces FIFO, and kitting that brings components to the workstation. For a fraction of the cost, and without locking the organisation in for a decade.
Not to be confused with
- An AS/RS crane is not racking. Racking is the storage structure; the crane is the machine that reaches it.
- Nor is it a conveyor: a conveyor moves goods in a line, a crane stores and retrieves at height.
- Goods-to-person systems using shuttles or mobile robots answer a neighbouring need with a different architecture, often more modular and easier to evolve.
Frequently asked questions
- How does an AS/RS crane differ from a forklift?
- A forklift is driven by an operator and needs wide aisles. The crane is automatic, runs in a dedicated narrow aisle and reaches far higher. One is versatile, the other is specialised and far denser.
- At what volume does it pay off?
- There is no universal threshold: it depends on the price of floor space, the number of movements per hour and how stable the activity is expected to be. The scale of the investment in practice demands a long horizon and firm volumes.
- Are there intermediate solutions?
- Yes, and they are often underrated. Flow racks densify and guarantee FIFO with no automation at all. Kitting removes searching at the workstation. Both can be reconfigured, which an automated warehouse cannot.
On the shop floor
MaKitLean does not build AS/RS cranes. If the question is on your table, it is worth asking plainly: are you trying to gain floor space, to make inventory reliable, or to stop operators walking the shop floor? All three needs are real, and only the first necessarily leads to heavy automation.