Production Planning and Scheduling in Flexible Assembly Systems

Flexibleassemblysystems(FASs)haveemergedasaresultofthedevelop- mentsinmanufacturingandcomputertechnology. Currentmarketrequire- mentscharacterizedby -increasingnumberofdifferenttypesandversionsofproducts, -smallerbatchsizes,and -shorterlife-timeofproducts, stronglydeterminethecompetitivenessinproductionassemblyandaddi- tionallycontributetothedevelopmentofflexibleautomatedassembly. For example,attheendof1986[33]40%ofJapaneserobotswerespecialized inassemblyascomparedwithonly10%ofEuropeanrobots. Theremain- ing90%wereusedinwelding,painting,andhandling. Theintroductionof flexibleautomatedassemblytohigh-techsectorswhereassemblycostsare criticalistheaimofmajorEuropeanprojectssuchasESPRITandBRITE programmesandtheFAMOS-EUREKAproject,e. g. ,[33,34]. Thebookdealswithproductionplanningandschedulinginflexibleassem- blysystems. ThereaderisfamiliarizedwiththeFASplanningandschedul- ingissuesforwhichvariousoperationsresearchmodellingandsolutionap- proachesarediscussed. Inparticular,applicationsofintegerprogrammingto theFASshort-termplanningandfastcombinatorialheuristicstotheFAS schedulingarediscussed. Thematerialinthebookhasbeendividedintosevenchapters. Chapter1presentstheoverallstructureandhardwarecomponentsand featuresofaflexibleassemblysystem. TheFASsclassificationisprovided andillustratedwithindustrialapplicationsofmechanicalpartassemblyand printedcircuitboard(PCB)assembly. Chapter2discussesmajorissuesinthedesign,planningandschedulingof flexibleassembly. BasicconfigurationsofFASsandmaterialflownetworksare presentedandvariousapproachestodesignforautomatedassemblyandto assemblyplanningarediscussed. TheFASproductionplanningandschedul- ingareconsideredwithinahierarchicalframeworkwithmachineloadingand assemblyroutingatanupperlevelandmachineandvehicleschedulingata lowerlevel. Finally,specificissuesinplanningandschedulingofPCBassem- blyarediscussed. VIII Preface InChapter3variousbi-objectiveintegerprogrammingmodelsandso- lutionapproachesarepresentedformachineloadingandassembly-routing inFASs. Aninteractiveprocedureisproposedforsimultaneousloadingand routingbasedonweightingapproachandalexicographicalgorithmisgiven forsequentialloadingandroutingwithalinearrelaxationloadingheuristic andanetworkflowroutingmodel. Numericalexamplesillustratepossible applicationsofthemodellingandsolutionapproachespresented. InChapter4thesequentialmodellingandsolutionapproachproposedin Chapter3hasbeenextendedforabicriterionmachineloadingandassembly routingwithsimultaneousassemblyplanselectioninageneralFASandina flexibleassemblyline. Numericalexamplesareprovidedtoillustratepossible applicationsoftheapproachproposed. Chapter5presentsmathematicalprogrammingformulationsforsimul- taneousloadingandschedulinginflexibleassemblycells. Theformulations areillustratedwithpracticalapplicationsinmechanicalpartassemblywith arobotassemblycellandinPCBassemblyonacomponentplacementma- chine. Chapter6isdevotedtoproductionschedulinginflexibleassemblylines whereseveralassemblystagesinseriesareeitherseparatedbyfiniteinter- mediatebuffersortherearenobuffersbetweenthestages,andeachstage consistsofoneormoreidenticalparallelmachines. Fastpush-typeschedul- ingheuristicsareproposedforthelinewithlimitedintermediatebuffersor thelinewithnoin-processbuffers. Foracomparison,apull-typeschedul- ingstrategyisillustratedwithsomerecentresultsfortheJust-In-Timeand multilevelschedulingofflexibleassemblylines. Numericalexamplesprovide thereaderwithpossibleapplicationsofthevariousmodellingandsolution approachespresented. InChapter7simultaneousschedulingofassemblystationsandautomated guidedvehiclesisdiscussedforageneralFASandtwodifferentsolutionap- proachesarepresented:(i)amulti-levelapproach,inwhichfirstmachine loadingandassemblyroutingproblemissolvedandthen,giventaskassign- mentsandassemblyroutesselected,detailedmachineandvehicleschedules aredetermined;(ii)asingle-levelapproach,inwhichmachineandvehicle schedulesaredirectlydeterminedwithnoinitialloadingandroutingdeci- mentscharacterizedby -increasingnumberofdi...