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Asanintroductiontothesubsequentdiscussionsofproductionsystemsandadvancedmanufacturingtechnologiesitisusefultopresentadefinitionofthetermmanufacturingsystem.Amanufacturingsystemcanbedefinedasaseriesofvalue-addingmanufacturingprocessesconvertingtherawmaterialsintomoreusefulformsandeventuallyfinishedproducts.
Inthemodernmanufacturingsetting,flexibilityisanimportantcharacteristic.Itmeansthatamanufacturingsystemisversatileandadaptable,whilealsocapableofhandlingrelativelyhighproductionruns.Aflexiblemanufacturingsystemisversatileinthatitcanproduceavarietyofparts.Itisadaptablebecauseitcanbequicklymodifiedtoproduceacompletelydifferentlineofparts.
Aflexiblemanufacturingsystemisanindividualmachineorgroupofmachinesservedbyanautomatedmaterialshandlingsystemthatiscomputercontrolledandhasatoolhandlingcapability.Becauseofitstoolhandlingcapabilityandcomputercontrol,suchasystemcanbecontinuallyreconfiguredtomanufactureawidevarietyofparts.Thisiswhyitiscalledaflexiblemanufacturingsystem.
AFMStypicallyencompasses:
*Processequipmente.g.,machinetools,assemblystations,androbots
*Materialhandlingequipmente.g.,robots,conveyors,andAGVs(automatedguidedvehicles)
*Acommunicationsystem
*Acomputercontrolsystem
Flexiblemanufacturingrepresentsamajorsteptowardthegoaloffullyintegratedmanufacturing.Itinvolvesintegrationofautomatedproductionprocesses.Inflexiblemanufacturin,theautomatedmanufacturingmachineandtheautomatedmaterialshandlingsystemshareinstantaneouscommunicationviaacomputernetwork.Thisisintegrationonasmallscale.
Flexiblemanufacturingtakesamajorsteptowardthegoaloffullyintegratedmanufacturingbyintegratingseveralautomatedmanufacturingconcepts:
*Computernumericalcontrol(CNC)ofindividualmachinetools
*Distributednumericalcontrol(DNC)ofmanufacturingsystems
*Automatedmaterialshandlingsystems
*Grouptechnology(familiesofparts)
Whentheseautomatedprocesses,machines,andconceptsarebroughttogetherinoneintegratedsystem,anFMSistheresult.HumansandcomputersplaymajorrolesinanFMS.Theamountofhumanlaborismuchlessthanwithamanuallyoperatedmanufacturingsystem,ofcourse.However,humansstillplayavitalroleintheoperationofanFMS.Humantasksincludethefollowing:
*Equipmenttroubleshooting,maintenance,andrepair
*Toolchangingandsetup
*Loadingandunloadingthesystem
*Datainput
*Changingofpartsprograms
*Developmentofprograms
Flexiblemanufacturingsystemequipment,likeallmanufacturingequipment,mustbemonitoredforbugs,malfunctions,andbreakdowns.Whenaproblemisdiscovered,ahumantroubleshootermustidentifyitssourceandprescribecorrectivemeasures.Humansalsoundertaketheprescribedmeasurestorepairthemalfunctioningequipment.Evenwhenallsystemsareproperlyfunctioning,periodicmaintenanceisnecessary.
Humanoperatorsalsosetupmachines,changetools,andreconfiguresystemsasnecessary.ThetoolhandlingcapabilityofanFMSdecreases,butdoesnoteliminateinvolvementintoolchangingandsetup.ThesameistrueofloadingandunloadingtheFMS.Oncerawmaterialhasbeenloadedontotheautomatedmaterialshandlingsystem,itismovedthroughthesystemintheprescribedmanner.However,theoriginalloadingontothematerialshandlingsystemisstillusuallydonebyhumanoperators,asistheunloadingoffinishedproducts.
Humansarealsoneededforinteractionwiththecomputer.HumansdeveloppartprogramsthatcontroltheFMSviacomputers.TheyalsochangetheprogramsasnecessarywhenreconfiguringtheFMStoproduceanothertypeofpartorparts.Humansplaylesslabor-intensiverolesinanFMS,buttherolesarestillcritical.
ControlatalllevelsinanFMSisprovidedbycomputers.IndividualmachinetoolswithinanFMSarecontrolledbyCNC.TheoverallsystemiscontrolledbyDNC.Theautomatedmaterialshandlingsystemiscomputercontrolled,asareotherfunctionsincludingdatacollection,systemmonitoring,toolcontrol,andtrafficcontrol.Human/computerinteractionisthekeytotheflexibilityofanFMS.
1HistoricalDevelopmentofFlexibleManufacturing
Flexiblemanufacturingwasborninthemid-1960swhentheBritishfirmMolins,Ltd.DevelopeditsSystem24.System24wasarealFMS.However,itwasdoomedfromtheoutsetbecauseautomation,integration,andcomputercontroltechnologyhadnotyetbeendevelopedtothepointwheretheycouldproperlysupportthesystem.ThefirstFMSwasadevelopmentthatwasaheadofitstime.Assuch,itwaseventuallydiscardedasunworkable.
Flexiblemanufacturingremainedanacademicconceptthroughtheremainderofthe1960sand1970s.