A Flexible Manufacturing System is a production system consisting of sets of CNC machine tools, interconnected by an automated material handling and storage system and controlled by a central system.

FMS components

• Work stations
• Material Handling and Storage Systems
• Computer Control System
• Human Resources

Work Stations: The work stations used in FMS is CNC machine tools. Most common is the CNC machining Center. CNC machining centers possess features that make them compatible with FMS, including automatic tool changing and tool storage, use of pelletized work parts.

Material Handling and Storage Systems: The material handling function is shared between the Primary Handling System and the Secondary Handling System. Primary handling system typically consists of conveyor system, RGVs, AGVs etc. It is supported by a automated storage system. Secondary handling system consists of transfer devices, automatic pellet changers, etc. The function of the secondary handling system is to transfer work from the primary system to machine tool or other processing station.

Computer Control System: The FMS includes a distributed computer system that is interfaced to the workstations, material handling system and other hardware components. A typical FMS computer system consists of a central computer and microcomputer controlling individual machines and other components. The central computer achieves smooth overall operation of system.

Human Resources: Humans are needed to maintain the operations of the FMS. Duties like loading and unloading of workparts to the system, maintenance, change of tools, programming the operating systems, management etc. are performed by humans.

Direct numerical control can be defined as a manufacturing system in which a number of machines are controlled by a computer through direct connection and in real time. The DNC computer is designed to provide instructions t each machine tool on demand. When the machine needs control commands, they are communicated to it immediately. DNC also involves data collection and processing from the machine tool back to the computer.

Components of a DNC system are:

• Central computer
• Bulk memory which stores the part program
• Telecommunication lines
• Machine tools

The computer calls the part program instructions from bulk storage ans sends them to the individual machines as need arises. It also receives data back from the machine. This two-way information flow occurs in real time, which means that each machine’s request for information must be satisfied almost instantaneously. Similarly, the computer must always be ready to receive information from the machines and to respond accordingly. The remarkable feature of the DNC system is that the computer is serving a large number of separate machine tools, all in real time.

Depending on the number of machines and the computational requirements that are imposed on the computer, it is sometimes necessary to make use of satellite computers. These satellites are mini computers, and they serve to take some of the burden off the central computer. Each satellite controls several machines. Groups of part program instructions are received from the central computer and stored in buffers. They are then dispensed to the individual machines as required. Feedback data from the machines are also stored in the satellite buffer being collected at the central computer.