AS/RS - cranes, miniloads and shuttle systems

How does AS/RS - cranes, miniloads and shuttle systems work, step by step?

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   Step 1: Define the throughput and the load before anything else

   The equipment supplier sizes the system from the operator's throughput brief: how many movements in and out per hour, at peak and average, on what load carrier, and to what availability. That brief sets the number of aisles, the number of machines, the height and the length of the store. It cannot be revised later without revising the building, so it is challenged hard and signed off early.

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   Step 2: Decide clad-rack or racking inside a building

   A clad-rack store uses the racking itself as the building structure, with cladding and roof fixed to it. It is efficient and it is committing, because the racking and the building become one thing that cannot be altered independently. The alternative is a conventional shed with the racking installed inside it, which costs more volume but keeps the two separable. The decision is taken jointly by the structural engineer, the racking designer and the equipment supplier, and it changes the planning, foundation and fire strategy work that follows.

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   Step 3: Design the foundations and floor to the machine's requirements

   A tall automated store puts concentrated loads into the ground and demands tolerances that ordinary warehouse floors do not meet. The runway for each machine has to be laid within the tolerance the equipment supplier states, and the structural engineer designs the slab and foundations for the loads and settlements the system can accept. Those tolerances are surveyed and accepted before the machines are delivered, because correcting them afterwards means lifting equipment out again.

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   Step 4: Erect the racking structure to equipment tolerances

   The racking is erected as a structure and checked as one, but to the tighter tolerances the machines require rather than to manual handling tolerances. Verticality over the full height, rail straightness, and the position of every load position relative to the machine datum all matter. The erection sequence, the temporary stability arrangements and the access provisions are planned by the installer because working at these heights inside a partly built structure is the main safety exposure of the whole project.

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   Step 5: Install the machines, rails and top guides

   Bottom rails and top guides are installed and aligned, and the cranes, miniloads or shuttles are lifted in and assembled. This is heavy lifting inside a tall structure and it is planned as a lifting operation in its own right. Power supply, festoon or busbar, communications and safety circuits are installed alongside. Nothing moves under power until the mechanical installation is signed off.

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   Step 6: Install conveyors, transfer points and the interfaces

   An AS/RS is only useful if loads reach it and leave it. Infeed and outfeed conveyors, transfer cars, profile and weight checks that reject a load the machine cannot handle, labelling and scanning points, and the interface with the manual part of the operation are all installed and aligned. The profile check at the infeed is worth its cost many times over, because a load that does not fit is the commonest cause of a stopped aisle.

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   Step 7: Commission in stages, then prove with real product

   Commissioning runs from powered movement without load, through single-machine cycles, to full-rate running with the warehouse management system driving. Exception handling, recovery from a stopped machine, manual retrieval routines and the behaviour on power loss are all proved. Then the system runs with real product at real rates for an agreed period. On most projects this stage takes months, and the operational go-live date is set from it rather than from the mechanical completion date.

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   Step 8: Hand over with load notices, access control and a planned inspection route

   Load notices are issued for the racking as for any other system. The automated aisles become a controlled area with interlocked access, and the isolation and entry procedure is trained and handed over rather than written and filed. Because nobody walks these aisles daily, the inspection regime has to be planned deliberately: a competent inspector examines the structure on the agreed cycle, any impact damage is assessed by a competent person before the aisle returns to use, and any change to the load carrier or the loading arrangement goes back to the racking designer and the equipment supplier together.