Automated Storage and Retrieval System

In large manufacturing establishments, the volume of items to be stored and retrieved becomes so large that the manual means of doing so becomes extremely unreliable and time consuming. The large volumes also call for proper information management procedures in order to reduce the duplication and reduction of inventory costs.

Automated Storage and Retrieval System (AS/RS) play a central role in the automated factory. The AS/RS not only control inventories, but also keep track of parts and materials in process or transit. In other words, the AS/RS has the ability to know where everything is, on a real time basis, even as the material moves within the factory. The importance of it for management to make manufacturing decisions based on accurate real time information can be understood from the fact that in-process materials rarely spend more than 5% of their time being worked on, and that the remaining 95% is spent in transit or storage. Thus, it becomes easier to visualise the role of materials handling and storage system within an automated factory.

An AS/RS, sometimes also referred to as automated warehouse, is a combination of equipment and controls, which handles the stores and retrieves material faster and with greater safety and efficiency than conventional material handling and storage systems. It contains several rows of storage racks and storage and retrieval devices (stacker cranes). The system can be related to other external devices like conveyors or Automated Guided Vehicles (AGV) for transferring material (in trays or pallets) to the shop floor / palletising stations.

The incoming items are very first sorted and after that assigned to pallets. The pallet loads are then routed by weighing and sizing stations to make sure that they are within the load and size limits. The accepted ones are transported to the pickup and delivery (P and D) stations, along with the details of the pallet contents that communicated to the central computer. This computer assigns the pallet a storage location within the rack and stores the location in the memory. The pallet is moved from P and D station to storage by storage and retrieval machines (S/R machines), or stacker crane. Upon receipt of a request for an item, the computer will search its memory for storage location and direct the stacker crane to retrieve the pallet. The supporting transportation will transport the pallets from P and D station to its final destination.