运营管理第14版蔡斯ipptchap011

ProcessDesignandAnalysis ChapterEleven Copyright 2014byTheMcGraw HillCompanies Inc Allrightsreserved McGraw Hill Irwin LearningObjectives LO11 1 Exemplifyatypicalbusinessprocessandhowitcanbeanalyzed LO11 2 Comparedifferenttypesofprocesses LO11 3 Explainhowjobsaredesigned LO11 4 Analyzemanufacturing service andlogisticsprocessestoensurethecompetitivenessofafirm 11 2 ProcessAnalysis Process anypartofanorganizationthattakesinputsandtransformsthemintooutputsCycletime theaveragesuccessivetimebetweencompletionsofsuccessiveunitsUtilization theratioofthetimethataresourceisactuallyactivatedrelativetothetimethatitisavailableforuse 11 3 AnalyzingaLasVegasSlotMachine AnalyzingthemechanicalslotmachineAnalyzingthenewelectronicslotmachineComparisonTheslotmachineisoneofmanycasinoprocesses 11 4 ProcessFlowcharting Processflowcharting theuseofadiagramtopresentthemajorelementsofaprocessThebasicelementscanincludetasksoroperations flowsofmaterialsorcustomers decisionpoints andstorageareasorqueues Itisanidealmethodologybywhichtobeginanalyzingaprocess 11 5 FlowchartSymbols 11 6 ProcessFlowchartExample SlotMachine 11 7 TypesofProcesses 11 8 Buffering Blocking andStarving Buffer astorageareabetweenstageswheretheoutputofastageisplacedpriortobeingusedinadownstreamstageBlocking occurswhentheactivitiesinastagemuststopbecausethereisnoplacetodeposittheitemStarving occurswhentheactivitiesinastagemuststopbecausethereisnoworkBottleneck stagethatlimitsthecapacityoftheprocess 11 9 MultistageProcesswithBuffer 11 10 OtherTypesofProcesses Serialflowprocess asinglepathforallstagesofproductionParallelprocess someofproductionhasalternativepathswheretwoormoremachinesareusedtoincreasecapacityLogisticsprocesses themovementofthingssuchasmaterials people orfinishedgoods 11 11 Make to StockversusMake to Order Make to orderOnlyactivatedinresponsetoanactualorder Bothwork in processandfinishedgoodsinventorykepttoaminimum Make to stockProcessactivatedtomeetexpectedorforecastdemand Customerordersareservedfromtargetstockinglevel HybridCombinesthefeaturesofbothmake to orderandmake to stock 11 12 MeasuringProcessPerformance 11 13 ProductionProcessMappingandLittle sLaw TotalaveragevalueofinventorySumofthevalueofrawmaterials work in process andfinishedgoodsinventoryInventoryturnsCostofgoodssolddividedbytheaverageinventoryvalueDays of supplyInverseofinventoryturnsscaledtodaysLittle slawThereisalong termrelationshipamonginventory throughput andflowtimeInventory ThroughputratexFlowtime 11 14 Example11 1 CarBatteries Averagecost 4512hourstomakeacarAssembles200carsper8 hourshiftCurrentlyoneshiftHoldsonaverage8 000batteriesinrawmaterialinventory 11 15 Example11 1 AverageInventory WIP ThroughputxFlowtimeWIP 25batteriesx12hoursWIP 300batteriesTotal 8 000 300 8 300batteries 11 16 Example11 1 ValueandFlowTime Value 8 300 x 45 375 000Flowtime Inventory ThroughputFlowtime 8 000 200 40days 11 17 BehavioralConsiderationsinJobDesign SpecializationoflaborMadehigh speed low costproductionpossibleGreatlyenhancedstandardoflivingAdverseeffectsonworkersJobenrichmentMakingjobmoreinterestingtotheworkerHorizontalenrichment workerperformsagreaternumberofvarietyoftasksVerticalenrichment workerisinvolvedinplanning organizing andinspectingwork 11 18 WorkMeasurementandStandards Workmeasurementisaprocessofanalyzingjobsforthepurposeofsettingtimestandards Whyuseit ScheduleworkandallocatecapacityMotivateandmeasureworkperformanceEvaluateperformanceProvidebenchmarks 11 19 WorkMeasurementTechniques DirectmethodsTimestudyWorksamplingIndirectmethodsPredeterminedmotion timedatasystemElementaldata 11 20 Example11 2 BreadMaking CurrentLayout 11 21 Example11 2 Runningat100LoavesperHour Bothbreadmakingandpackagingoperatethesameamountoftime Capacityis100loavesperhour Packagingisidleforaquarterhour Has75percentutilization 11 22 Example11 2 BreadMakingonTwoParallelLines 11 23 Example11 2 MultipleShifts Breadmakingrunstwoshifts Produces200 x8x2 3 200Packagingrunsthreeshifts Produces133 3x8x3 3 200Capacitiesareroughlyequal 11 24 Example11 3 ARestaurant 11 25 Considertherestaurantinthecasino Becauseitisimportantthatcustomersbeservedquickly themanagershavesetupabuffetarrangementwherecustomersservethemselves Thebuffetiscontinuallyreplenishedtokeepitemsfresh TofurtherspeedserviceFixedamountischargedforthemeal Customerstakeanaverageof30minutestogettheirfoodandeat Theytypicallyeatingroups orcustomerparties oftwoorthreetoatable Therestauranthas40tables Eachtablecanaccommodatefourpeople Whatisthemaximumcapacityofthisrestaurant Example11 3 SolutionApproach 11 26 Utilization Itiseasytoseethattherestaurantcanaccommodate160peopleseatedattablesatatime Actually inthissituation itmightbemoreconvenienttomeasurethecapacityintermsofcustomerpartiesbecausethisishowthecapacitywillbeused Iftheaveragecustomerpartyis2 5individuals thentheaverageseatutilizationis62 5percent 2 5seats party4 4seats table whentherestaurantisoperatingatcapacity Cycletime Whenoperatingatcapacity is0 75minute 30minutes table 40tables So onaverage atablewouldbecomeavailableevery0 75minuteor45seconds Capacity Therestaurantcouldhandle80customerpartiesperhour 60minutes 0 75minute party Example11 3 ChallengesinRestaurantProblem 11 27 Theproblemwiththisrestaurantisthateveryonewantstoeatatthesametime Managementhascollecteddataandexpectsthefollowingprofileforcustomerpartiesarrivingduringlunch whichrunsfrom11 30a m until1 30p m Customersareseatedonlyuntil1 00p m Example11 3 ArrivalData 11 28 Example11 3 Restaurant 11 29 Restaurantoperatesfortwohoursforlunchandthecapacityis80customerpartiesperhour Asimplewaytoanalyzethesituationistocalculatehowweexpectthesystemtolookintermsofnumberofcustomersbeingservedandnumberwaitinginlineattheendofeach15 minuteinterval asnapshotevery15minutes Thekeytounderstandingtheanalysisistolookatthecumulativenumbers Thedifferencebetweencumulativearrivalsandcumulativedeparturesgivesthenumberofcustomerpartiesintherestaurant thoseseatedattablesandthosewaiting Becausethereareonly40tables whenthecumulativedifferencethroughatimeintervalisgreaterthan40 awaitinglineforms Cycletimefortheentirerestaurantis45secondspercustomerpartyatthistime thismeansthatonaverage atableemptiesevery45secondsor20tablesemptyduringeach15 minuteinterval Thelastpartywillneedtowaitforalloftheearlierpartiestogetatable sotheexpectedwaitingtimeisthenumberofpartiesinlinemultipliedbythecycletime Example11 3 continued 11 30 Inthefollowingtable whenthecumulativenumberofpartiesis50 thereare10partieswaitingtobeseated sincethereareonly40tables Theaveragetimetheywaitis10 x45secs 7 5minutes During12 00to12 15 partiesthatarrivedduring11 30to11 45wouldhaveleft whichmakesthecumulativenumberofpartiesattheendof12 15 50 numberattheendof12 00 30 arrivalsduring12 00to12 15 15 departuresduring12 00to12 15 65 Example11 3 CustomerStatus 11 31 Example11 3Customersvs Time 11 32 Example11 4 TheBalabus TouristBus inParis TwohoursfortherouteduringpeaktrafficRoutehas60stopsEachbushasseatingcapacityof50Another30passengerscanstandBusymuchoftheday 11 33 Example11 4 InitialAnalysis Withonebus maximumwaitistwohours Ifbusishalfwaythroughcycle waitiso