Automated Storage and Retrieval System - Overview

Overview

AS/RS systems are devices designed for automated storage and retrieval of parts and items in manufacturing, distribution, retail, wholesale and institutions.They were invented in the 1980's. They are compact units that utilize the unused overhead space of a plant or warehouse, and convert to live storage of product. Items can be placed on trays or hang from bars, which are attached to chains/drives in order to move up and down. They focus on bringing "goods to the man" rather than manual walking and searching. Space savings, increased productivity/reduced labor, increased accuracy and reduced inventory levels are some of the primary benefits. Ideal for lean manufacturing, sustainability, six sigma, Kanban, JIT and other value added methodologies and processes. The equipment required for an AS/RS include a Storage & Retrieval Machine, or SRM, that is used for rapid storage and retrieval of material. SRM are used to move loads vertically or horizontally. SRM can also move laterally to place objects in correct storage location.

The traditional vending machine is the most common and familiar AS/RS system but because the application is to do with retail sales, the logistic concept of a vending machine is missed.

The trend towards just in time production often requires sub-pallet level availability of production inputs, and AS/RS is a much faster way of organizing the storage of smaller items next to production lines. Traditional high bay warehouses are designed with pallet storage in mind, and if goods are being delivered in sub pallet quantities, high bay warehouses are problematic.

Material Handling Institute of America (MHIA), the non-profit trade association for the material handling world, and its members have broken AS/RS into two primary segments: Fixed Aisle and Carousels/Vertical Lift Modules (VLMs). Both sets of technologies provide automated storage and retrieval for parts and items, but use different technologies. Each technology has its unique set of benefits and disadvantages (like everything in the world). Fixed Aisle systems are characteristically larger systems whereas carousels and Vertical Lift Modules are used individually or grouped, but in small to medium-sized applications.

Fixed-aisle AS/RS is categorized into three main types: single-masted, double masted, and man-aboard. Most are supported on a track and ceiling guided at the top by guide rails or channels to ensure accurate vertical alignment, although some are suspended from the ceiling. The 'shuttles' that make up the system travel between fixed storage shelves to deposit or retrieve a requested load (ranging from a single book in a library system to a several ton pallet of goods in a warehouse system). As well as moving along the ground, the shuttles are able to telescope up to the necessary height to reach the load, and can store or retrieve loads that are several positions deep in the shelving. A semi-automated system can be achieved by utilizing only specialized shuttles within an existing rack system.

To provide a method for accomplishing throughput to and from the AS/RS and the supporting transportation system, stations are provided to precisely position inbound and outbound loads for pickup and delivery by the crane.

In addition, there are five types of AS/RS devices called Unit-load AS/RS, Mini-load AS/RS, Vertical Lift Modules (VLMs), Horizontal Carousels and Vertical Carousels. These systems are used either as stand-alone units or in integrated workstations called pods or systems. These units are usually integrated with various types of pick to light systems and use either a microprocessor controller for basic usage or inventory management software. These systems are ideal for increasing space utilization up to 90%, productivity levels by 90%, accuracy to 99.9%+ levels and throughput up to 750 lines per hour/per operator or more depending on the configuration of the system.