Robust planninginoptimizationforproductionsystemsubjecttorandommachine breakdown andfailureinrework

This studyisconcernedwithrobustplanninginoptimization,specificallyindeterminingtheoptimal run timeforproductionsystemthatissubjecttorandombreakdownsunderabort/resume(AR)control policy andfailureinrework.Inmostreal-lifeproductionprocesses,generationofdefectiveitemsand breakdowns ofmanufacturingequipmentareinevitable.Inthisstudy,randomdefectiverateisassumed and allmanufactureditemsarescreened.Theperfectquality,reworkableandscrapitemsareidentified and separated;failure-in-reworkisassumed.Thesystemisalsosubjecttorandommachinebreakdown; and whenitoccurs,theARpolicyisadopted.Undersuchpolicy,theproductionoftheinterruptedlot will beimmediatelyresumedwhenthemachineisrestored.Mathematicalmodelingandderivationof the production-inventorycostfunctionsforbothsystemswith/withoutbreakdownsarepresented.The renewal rewardtheoremisusedtocopewiththevariablecyclelengthwhenintegratingcostfunctions. The long-runaveragecostperunittimeisobtained.Theoremsonconvexityandonboundsofproduction run timeareproposedandproved.Arecursivesearchingalgorithmisdevelopedforlocatingtheoptimal run timethatminimizestheexpectedproduction-inventorycosts.Anumericalexamplewithsensitivity analysis isprovidedtogiveinsightintotheoptimaloperationalcontrolofsuchanunreliablesystem.