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1、* Process equipment e.g. , machine tools, assembly stations, and robots* Material handling equipment e.g. , robots, conveyors, and AGVs （automated guided vehicles） * A communication system* A computer control system Flexible manufacturing represents a major step toward the goal of fully integrated m

2、anufacturing. It involves integration of automated production processes. In flexible manufacturin , the automated manufacturing machine and the automated materials handling system share instantaneous communication via a computer network. This is integration on a small scale. Flexible manufacturing t

3、akes a major step toward the goal of fully integrated manufacturing by integrating several automated manufacturing concepts: * Computer numerical control （CNC） of individual machine tools* Distributed numerical control （DNC） of manufacturing systems* Automated materials handling systems* Group techn

4、ology （families of parts）When these automated processes, machines, and concepts are brought together in one integrated system, an FMS is the result. Humans and computers play major roles in an FMS. The amount of human labor is much less than with a manually operated manufacturing system, of course.

5、However, humans still play a vital role in the operation of an FMS. Human tasks include the following: * Equipment troubleshooting, maintenance, and repair* Tool changing and setup * Loading and unloading the system* Data input* Changing of parts programs* Development of programsFlexible manufacturi

6、ng system equipment, like all manufacturing equipment, must be monitored for bugs, malfunctions, and breakdowns. When a problem is discovered, a human troubleshooter must identify its source and prescribe corrective measures. Humans also undertake the prescribed measures to repair the malfunctioning

7、 equipment. Even when all systems are properly functioning, periodic maintenance is necessary.Human operators also set up machines, change tools, and reconfigure systems as necessary. The tool handling capability of an FMS decreases, but does not eliminate involvement in tool changing and setup. The

8、 same is true of loading and unloading the FMS. Once raw material has been loaded onto the automated materials handling system, it is moved through the system in the prescribed manner. However, the original loading onto the materials handling system is still usually done by human operators, as is th

9、e unloading of finished products.Humans are also needed for interaction with the computer. Humans develop part programs that control the FMS via computers. They also change the programs as necessary when reconfiguring the FMS to produce another type of part or parts. Humans play less labor-intensive

10、 roles in an FMS, but the roles are still critical.Control at all levels in an FMS is provided by computers. Individual machine tools within an FMS are controlled by CNC. The overall system is controlled by DNC. The automated materials handling system is computer controlled, as are other functions i

11、ncluding data collection, system monitoring, tool control, and traffic control. Human/computer interaction is the key to the flexibility of an FMS.1 Historical Development of Flexible ManufacturingFlexible manufacturing was born in the mid-1960s when the British firm Molins, Ltd. Developed its Syste

12、m24. System 24 was a real FMS. However, it was doomed from the outset because automation, integration, and computer control technology had not yet been developed to the point where they could properly support the system. The first FMS was a development that was ahead of its time. As such, it was eve

13、ntually discarded as unworkable.Flexible manufacturing remained an academic concept through the remainder of the 1960s and 1970s. However, with the emergence of sophisticated computer control technology in the late 1970s and early 1980s, flexible manufacturing became a viable concept. The first majo

14、r users of flexible manufacturing in the United States were manufacturers of automobiles, trucks, and tractors.2 Rationale for Flexible Manufacturing In manufacturing there have always been tradeoffs between production rates and flexibility. At one end of the spectrum are transfer lines capable of h

15、igh production rates, but low flexibility. At the other end of the spectrum are independent CNC machines that offer maximum flexibility, but are capable only of low production rates. Flexible manufacturing falls in the middle of continuum. There has always been a need in manufacturing for a system t

16、hat could produce higher volume and production runs than could independent machines, while still maintaining flexibility.Transfer lines are capable of producing large volumes of parts at high production rates. The line takes a great deal of setup, but can turn out identical in a part can cause the e

17、ntire line to be shut down and reconfigured. This is a critical weakness because it means that transfer lines cannot produce different parts, even parts from within the same family, without costly and time-consuming shutdown and reconfiguration.Traditionally, CNC machines have been used to produce s

18、mall volumes of parts that differ slightly in design. Such machines are ideal for this purpose because they can be quickly reprogrammed to accommodate minor or even major design changes. However, as independent machines they cannot produce parts in large volumes or at high production rates.An FMS ca

19、n handle higher volumes and production rates than independent CNC machines. They cannot quite match such machines for flexibility, but they come close. What is particularly significant about the middle ground capabilities of flexible manufacturing is that most manufacturing situations require medium

20、 production rates to produce medium volumes with enough flexibility to quickly reconfigure to produce another part or product. Flexible manufacturing fills this long-standing void in manufacturing.Flexible manufacturing, with its ground capabilities, offers a number of advantages for manufacturers:*

21、 Flexibility within a family of parts* Random feeding of parts* Simultaneous production of different parts* Decreased setup time and lead time * More efficient machine usage * Decreased direct and indirect labor costs* Ability to handle different materials* Ability to continue some production if one

22、 machine breaks down 3 Flexible Manufacturing System ComponentsAn FMS has four major components:* Machine tools * Control system * Materials handling system *Human operators （1） Machine ToolsA flexible manufacturing system uses the same types of machine tools as any other manufacturing system, be it

23、 automated or manually operated. These include lathes, mills, drills, saws, and so on. The type of machine tools actually included in an FMS depends on the setting in which the machine will be used. Some FMS are designed to meet a specific, well-defined need. In these cases the machine tools include

24、d in the system will be only those necessary for the planned operations. Such a system would be known as a dedicated system.In a job-shop setting, or any other setting in which the actual application is not known ahead of time or must necessarily include a wide range of possibilities, machines capab

25、le of performing at least the standard manufacturing operations would be include. Such systems are known as general purpose systems. （2） Control SystemThe control system for an FMS serves a number of different control functions for system:* Storage and distribution of parts programs * Work flow cont

26、rol and monitoring * Production control *System/tool control/monitoringThe control area with the computer running the FMS control system is the center from which all activities in the FMS are controlled and monitored. The FMS control software is rather complicated and sophisticated since it has to c

27、arry out many different tasks simultaneously. Despite the considerable research that has been carried out in this area, there is no general answer to designing the functions and architecture of FMS software.The scheduler function involves planning how to produce the current volume of orders in the F

28、MS, considering the current status of machine tools, work-in-process, tooling, and so on. The scheduling can be done automatically or can be assisted by an operator. Most FMS control systems combine automatic and manual scheduling; the system generates an initial schedule that can be changed manually by the operator. The dispatcher function involves carrying out the schedule and coordinating the activities on the shop floor, that is, deciding when and where to transport a pallet, when to start a process on a machining center, and so on.The monitor function