1) Flow rack
Storage rack that utilizes shelves (metal) that are equipped with rollers or wheels. Such an arrangement allows product and materials to "flow" from the back of the rack to the front and therein making the product more accessible for small-quantity order-picking.
2) Pallet flow rack
May be considered back-to-back selective rack. Inclined conveyor wheel sections are installed in the rack enabling back-loaded pallets are allowed to flow by gravity to the front or pick face. Pallet flow rack is useful for the movement of fast-moving items and serves to increase density of storage and throughput.
3) Order picking
Order picking or order selection is the process of retrieving individual items (from storage locations) for the purpose of fulfilling an order for a customer. Schemes by which to achieve efficient order picking will vary widely. However, in all cases it involves locating the items in storage; creating a plan for retrieving the items; physically picking the items (either automatically or manually); sorting and/or assembling them into discrete orders; and in the end even packaging the orders for delivery. Although defined as a process, order picking cannot be achieved without the appropriate computer software and mechanical equipment, including the storage medium, such as pallet racks, shelving, AS/RS (including carousels) and flow delivery racks, and a means for transporting items from receiving to storage and from storage to packaging and shipment. A variety of industrial trucks and conveyors will be found in most order picking applications. Order picking may also involve robotic like devices for physically picking discrete items from their storage location. See also Warehouse Management Systems or WMS .