Mechanical Engineering - Design and Management of Production Systems

Completed notes of the course - Part 1

Complete course

Design &Management of ProductionSystem g ↓choosethe (byperfindicatessendingfeedbackinshorttime).&2.Definethemetricsforallp.i's(forlongterms -> Relatedto change PerformancePerformance PerformanceFramework:Performancedividedinto4classesii) Quality. ->Productionprocess -> Availability ->Relatedtostateofplant(Metrics - MeantimetoFailure(MTTF).Meantimeto Repair(MTTR),costoflostproduction,costofmaintenanceId↓correctivePreventivecafterfailure) >Internal(In-Housecompliance) ->reworks(Metrices no. ofreworks,irework,timespent onreworks,cost...->External(In-Fieldcompliance) -> warranty&returns(Mebice - no. ofreturnedproducts, no.ofintervensionsunderwarranty&cost,costoflossofreputation) - ---> specialdesigns &variations........Tg )R&Dtoo along withproduction.(Metrics:no.ofcustomizableparameters,varietiesoffered,etc.)decisions: ->no. ofquality controls&frequency -> no.2typeofactionsto preventdefects.costcost2totalNN Equalitycontrols W epreventionCinternalquality ⑧ X Centernalquality "¥ cquality(intentequalityControl- qualitycontrols>Prevention (ii)service! >Availability I >stock-outpersistency -> MTSonly>Promptness>DeliveryAccuracy &Completeness >Punctuality even ifonly/lineof anorder Availability: 1-%stockoutS isstock-out - entireorder:stock-out%. Availabilityorder:Fordersfullyavailable -I-#Orders stockout#Orderstotal#Orderstotal%. Availability lines1 - Allinesstockout#Linestotal%. Availabilityquantity:#Quantityavailable#Quantitytotal%. Availabilityitemi:#Itemavailable #Itemitotal Metric + stockout-cost(depends on customerbehaviorsstock-cutpersistency:howlongstock-outlasts.Metrics - #periodsinstock-out(#totalperiods,potentialorders.(slidePg35) Accuracy: relatedtodeliveriesevaluatessystemof order preparation.Metrics - (no.ofreturnsduetowrongdeliveries, no. of mistakesin delivery/No.oforders(orderlines)costofpenalty, costofduplicatingmanagement & accountingactiv S completeness: - allorderlinesaredeliveredatsametime Differentdeliveries for sameorderincreasescost&complexity.Metrics ->No. oforderrows fulfilled inI delivery/total rows, arg no. ofdeliveriesforeachorder,costoffractioneddeliveries. Promptness:Responsivenessofsystem, relatedtoLeadtime.(Shorter2.7bitterpromptness I time elapsedbetorderdate&deliverydate.Metrics -> Averageleadtime(Ideliverydate-orderdate)/totalorders,nooforders filledwithinx-days/total orders,no ofvines filled in undays/totallinesLeadtimediscussedlater(check). Punctuality: ->Istheproductdelivered in requested(aragreedtime? Timeelapsedfromdate requested or agreedMetrics -- no. oflateorders/no.oforderlines,averagedelayspenalty cast(forlatedeliveries - especially inM50),extracostsincurredtobe punctual(empressdeliveries,etc.)⑧ Delivering inadvancecanalsobea problemsometimes is ifthecustomerdoesnothavestoragespace LeadTime:Leadtimeis differentforMTS&MTO, .....->MTS:CustomerLT : Delivery time only (canbe0-retailstores, -> Relatedactivities:->1.Orderprocessing ->2.Orderpreparation ->b. Delivery. -> MTO, .. ...custome1.3:Dateof orderto Delivery /Production,storageincluded)(mandatory)Planning Index=Delivery1.T-To t a l1.TI1P>1 -> MTO,AT O. . .(allowed &>customer2.T->service(effectiveness)tocustomerrequest(iii)Flexibility: ->cost(efficience)ofreaction->Flexibityofplans:Howfast wecan change our productionplan.Frozenperiod -> periodinwhich wecan'tchange our plan...11 >tFrozentime4Flexibility+ I 234567-> Flexibilityofproductionmix: Possibilityofchanging unitsofeachproductproduced.Ex:500units 5320A or 500units-250AzwoB "¥ 250Metrics - Lotsize,setuptime,costofsetup,etc.-> Flexibilityofproductvolume:possibilityofproducing moreorlesswiththatproductionplanwithoutraising perunitsellingpriceorthetimerequiredtoproduce.In1500units 1200 units - flexibleifIcankeepsamep.700units-flexibleif Icankeepcant.Metrics ->utilizationlevelofproductioncapacity,availabilityofovertime/subcontractor,cest-volumecurve-> Flexibilityofproducts:Possibilityofintroducing new products.Relatedtoproductionsystem -> Jobshop:Flew->Productionline:FlexdMetrics ->time&cost forre-engineering (iv) -> Wo r k fo rc e>Productivityofproduction resources -> Machines/Plants - Materials -> stockturn-over&daysofinventory ->warehouseproductivity to ABC-ABCanalysisProductivityofproduction resources:1.Tr a d i t i o n a lway:Productivity -Ratioof timewecanuse forgoodproduction totimewecanusetheplant.Productivity = k Based onstatusof resources -> Organizational -> Managerial -> Te c h n o l o g i c a lProductivity di↓↓utilization(V)(n) N↓↓↓↓dNetUtilizate(UI)Availability(A)saturation(s)Yield(Y)(V): Howmuchtheplant isusedforproduction.%.U* = TheoreticalUtilizationtimeOpeningtimeT%A = ActualUtilizationtime = Tito teanotherTheoreticalUtilizationtimeItrway I ofmeas%.Az:Actualproductiontime -= Ttr-TM-TF-TPTavailal.TheoreticalUtilizationtimeTtr 105 = YU*x%Az: T-Ts -To -T M -Tc o -T E -T M -T P T TPOK + TPsiTs Efficiency(y): Howwellplant isused%os: Machining timeTTR - TPOK+TP = TA P -isActualproduction time = TA PTTR+TsTA P %Y -Actualproductioninstatime -TPOK - S Machining TimeTTRGoodunits-> To t a lproducedunits 1.7 = %5x%y = NoTA P j.y = (FPoki+Tpsi)+s-> standardtimesE(TPOKitTosi)+TS ->ActualtimesProductivity,P = YUx%.U= () basedonvolume(nottime,↑⑤)↑⑤.2.OverallEquipmentEffectiveness(OEE): ->Ratiooffullyproductivetimetoplannedproductivetime -> Tomeasureperformance&estimateproductioncapacity. - =..=>>> ...... . ⑳ =*°@°@°x ⑰ ⑦$). · Speedlosses - couldbeduetothereasonthatproductionhappensat a lowerratethemstandard. - speciallyimpwhennon-automated(workforceinvolved) ⑧ ⑱ @B -> Actual:isspecificproductstandardtime:productsproduced:Standardrate(orNominalproductionrate)POEEXGOEEProductionCapacity:units/yearCp = (p/h) x (%)productivatetimecauses decreasinggoodproductsProductivity>Fortraditionalmethod)Cp=Pmin xT1X (1-DA Defectrate Zu >(ForOEE)Cp:PminxPlannedprodTimexOEEifIalready↓considersdefectAOEEXPOEEXSOEErate noneedof(ID)b = productionrate(P(h) - pra productsPrixe - QuantityofitemsproducedTo t a ltime to producethem(setupincluded)->STD:Pmin=2:/Poki+Psi) + psi)UnitK:Pmix:2:(Rs/Rsi)(Poki+Psi)-> givesPainintermsof a [ilTpoki+Ypsi)productK. Wa re h o u s eProductivity: Checkwarehouseproductive or not>Tr a d i t i o n a l Stock Tu r n o v e rIndex(STI) I checkhowlongdemands->Days (oranyothertimefreeofInventory(DG) canbecoveredwithoutreplanchments.->ABCanalysis -> Check if Ihavetherightamountofstockofeachproduct. -> usefulonlyforlarge no.ofproducts. sikder Meaghi isstockTu r n o v e rIndex:Te l l susafterhowlongthestockrotatesintheinventory(orhowmanycyclesin a giventimeframe).STI = Iconsumption(1)year or monthAverageInventorylevel(AILExample:Demand:45pl/month(consideringconstantdemand) A Replenchment:1month,Orderquantity,8 : 40pl 40-All= B =20 plAl>ImImSa -Consumption(T2)year) x12 month/year = 480pl/year=STI: DY= 24Yyear N10- if,replenchment:1month,Aimch9 = 10pl/week. -> AlL=5p)(ii)Days(orweeksor yearsofInventory: Howmanydaystheexistinginventorycastswithoutreplenchment.DG4-headsto higherinventorycostDO1 : Days inperiod(e)butlewofficiencySTIExample:Demand:45pl/month(consideringconstantdemand) A Replenchment:1month,Orderquantity,8 : 40pl 40-All= B =20 plAl im 2ms-Consumption(T2)year) x12 month/year = 480pl/year=STI: DY= 24Yyear .: WOT = 4w/mx12m/y =2weeks24/7caseaexample:Was: 4WhimM=0.5 weeks · ifSTIRWOl(orDODd·whetherSTPwoldbetterorsilkwolddependson:- customertype(ifwillingtowait or noth - costofstockout - possibilityofstockout - producttype(perishable or not) vii)ABCAnalysis: Based on Paretorule/180-20)rule:Alargeproportionofproblemsresultfromasmallproportionofthecauses. Inventorydividedinto3classesbasedonannualdollarvolumeforbothstock&consumptionvalue.Commonthresholds:80% - 95%75%-90% ->obsolete - Eliminate①freq fulfillment,high -> finishedprod:promote-> reduce5.8obsofenceI rawmat:useinother opportunity products ifpossible.②Rarefulfillmentsrisk ->Newproducts,control -> removeconstraintriskofstouttofulfillmentpolicies --> spareparts - controlcen,ordermoreoften)③cyclicifinterestingpromotions&season) high no-> eliminateseasonalitylowno stock - Out h It interesting(stockouts)carefullyJIT,MTOincreasestock.obsoletes - eliminateToofferfullrange. ↑ * eff ggn gener Designof Manufacturingsystem: ·BasicDesign · Detailed Design (simulation,QuantitativemodelsBasic design: · Required timeforproduction(Hri)#hoursi = typeofmachine/process · Ava i l a b l etimeforproduction(Hai)#hoursavailableIfHri)Hai-morethan1machinerequired · Numberofmachines/processes(NitNi=HeriHaiFormorethanIproduct,totaltimeisthetimetoproducealltheproducts. JobShop: · Machines groupedtogether in differentdepartments onthebasisoftechnologicalprocessesinvolved · Laborisdivided&needshighspecializationofpeople · Eachproducthasitsown routingAdvantages: > Flexibility:(i)Intermsofvolume,alternativerouting(ii)Productionmin(iii)Newproducts ->Lowobsolenceofproductionsystem:sinceflexible, even ifproductchangesslightly,productionsystem canstillbeusedmakingadjustments. ->Low impactofbreakdown:-> EffectDisadvantages: > Managementofjobshop is complex.Aslotsofproductsin1machine,theidletimeismorein jobshop.Thishastobereduced. · Caryquestmachine(longwaitingtime) · Dueto longwaitingtimes,To t a lproductiontimeFot>)[ti-workingtimeof·leadtimehigh[:'Tco>M]machine; · Moreinventory · Highmanagerialcost - highoverallcost-> EfficiencylowJobshops areusedwhentherearea lotofproductstobeproducedbutin100volumes.JobshopDesigning Step1: Identificationoftheproductionin · #products · quantity tobeproduced inthesystem(83) Step2: Identificationofroutingsoftheproduct · favoriterouting · alternativeroutingStep3:Identificationofneededmachines(notsize) · averagesizeoflots/batches/product(3)&Amachine(i)N2i,j = No.oflotsofproduct; on machinetype; · Lotsizedependson Setup cost->inventoryholdingcostIf2glotsizelarger.If Inv,holdingcost4smallerlotsizeinventoriesinventoriesRInventorycost4RSetupcost - 400u setupcosttInventorycostt2004-2004average100ninventory ..... time ..... timeStep4:Competing(sunningup)timefortheoperationsferAmachinetype: AproductITij -> DoesnotincludesetuptimeStep5: ComputationofAnnualProductionHours(Hilneeded(machineis= Sessvis)et H2- "¥ > IfTijorThisgiven inminutesN = No.ofproductsProcessingTimeDij:Defectivenessrate=L1-yield)Di:To t a lgoodproductionSetupTimeThij:setuptimeforproduct;onmachine;Tijeminutesforproducing a unitofj on machine;Ai:Ava i l a b i l i t yofmachinetypeibetween0to1TRi = coefficientdepending ontrialsHei-coefficientrelated to howpeoplework - speed Step6: ComputationofAva i l a b l eHours(machinetypeisAHiCS) = WHixSx0↓shiftWHi= Wa k i n g hours3:coefficientrelatedtostrikes04s.)0(CSE):schedulingcoefficient018EX1Step7:Numberofmachines;Nils): c - notan integer.Roundedupbasedonthestuftsaturation.havinghigher numberofshiftsallowustohavelowernumberofmachines.Saturation,S:2TijNixAHiXANumberofmachinealsodepends on-> costofmachine -> possibilityofoutsensing, etc.Step8: Computationofnumber ofshifts · The shiftwhichminimizesthetotalcostofproductionsystemWFCiCs)+OPCiCS)+PIMimi+pIPFifi(ly)WFCiIS):Workforcecostcommual)OPCiCd = Operatingcest(annuall -> cacludingworkforceleg:energyPIM? : Purchasing&Installationofmachinei(t)micficcoefficientrelatedtoCRF(21strecoveryfactor - helpstofindannualcost. mizote"Fil: aRE;i = rateofreturnn= numberofperiodsPIPFT:Purchase&installationofproductionfacilities(investmentrelated)&PIPEgivenin Ely noneedto multiply withmior fir2options->same no ofshiftIdepartments "¥ > different no. ofshifts-bufferneededtostoreprod.Foreachbatch(orloft weneeda setup... Noofsetup:NAis ManufacturingCells: usedforproductshaving high demand(volumel,withless variability &stablecustomerdemand =@°=>-*⑦ _@⑤@⑦I⑧I characteristics:1.Cellsproducefamiliesofproducts -> Familiesareuniquelyassignedto1cell -> Allresourcesneededforthatfamilyofproducts are onlyinthatcell.2.Familiesofproductsarebased on affinity -> Geometrical(Size,Shape -> cycles/processes3.Groupsofmachines(resources)ofacellareinaplacewithdispositionbasedonthesequenceofprocessing.Advantages: 1.Muchmore rationalized&structuredflow 2.Ts e t u p&(becauseproducts are verysimilar)3. waitingtimed - leadtimed&sohadtimevariabilityf4.Workinprogress-Dueto waiting timet5. Management lesscomplex6.Jobenlargement&enrichment7.Morecontrolon quality. Disadvantages: 1.Lessflexibility 2.Mightneedmoremachinesthan jobshop3.ProblemsrelatedtobreakdownsGroupTe c h n o l o g y :Manufacturingcellsbasedon productsimilarity.DesigningManufacturingcells:Step1: Creatingfamiliesofproducts · Datacollectionregardingproductionmix ⑧ technologicalroutingStep2: Classificationofproductsw Step3:Standardizationofproducts⑧Step 4:StandardizationoftechnologicalroutingseStep5: Identificationofproductfamilies ->RankOrderClustering(ROC -> similarity(eefficient(SLC) : Step6: Identificationofmachinegroupsformingcells&Step 8: sizingofsinglecells · similar to Jobshop · saturationcellssaturationjobshopfamiliesbased on characteristicsofvisualfeaturesproductsassignedtocodes Tr a n s f e rLinesD · AlsocalledFlowlines · Inasequence,one aftertheotherCharacteristics:1.Flowisserial2.Highlyautomated(generally)ofproductsshouldbehighastable · Ifproductchangesafter a fewyears,theproductionsystemwillbecomeobsolete. · Sincemachinesarededicated to 1product(orverysimilarproducts) - unlessproductis in highdemandnoteconomicallyviable.4.Linemustbebalanced · cycletimesofeachworkstationshouldbesimilar · Balancedlineincreasesproductivityorreducescost.CT=5minCT=2minCT= 4minCT= 4minCT=3minCT= 4minmore balanced ->- M. -> Me -> Ms->M,M2M31productevery5min1productevery4minTy p e sofMachines: -> singlepurpose: · Machine'sspecialized to perform a specifictaskprecisely · Advantage:Highproductivity · Disadvantage:lowflexibility->Multipurpose/General: · Machinesthat can performmultipletasksbutwithlessprecision · Advantage:Highflexibility(forexample- in balancing or introducing new production · Disadvantage:lowproductivity.Advantages: 1.Simpleproductionmanagement · Designingnotsimple,butoncedesigned,asroutingsfixed,managementphasebecomeseasier.· Iproductat a time(evenif samemachineproducesothersimilarproducts-notatsametimes2.Highmachineutilization · Evenif more than1product in 1machine-sinceproducts are verysimilar - setuptimeslow · utilizationhigherthemorewellbalancedtheline.3.Lowspaceoccupied · Aslowques(ornone) -lessspaceneeded ->lowwaitingtimenegligible) - lowWIP -LowLT(Total(T= 2,(i) time reg to performoperations(neglectingtransfertimes · Becauseofautomation - thisalsomakesIdeterministic · Needofworkforceonly in limitedworkslike - monitoring,loading&unloadingmaterials warfare meseistisofproductsare e ↑ natteTr a n s .Linesareexpensive&are designedforhighproductivity.So, Disadvantages: increasingproduction can requirenewproductionline,makingitmoreexpensive asdueto automation,suchproductionsystem is designedtoworkforlongershifts&1.Lewflexibilityhours&so,increasingproductionvolumebyincreasingavailablenearsisnot · Intermsof - products an option.Butalsoforlowervolumes,itisnotcosteffective&thusaproblem. ->volumes(bothincaseofincreasingordecreasingvolumes)2.Highinvestmentneeded . Duetoautomation3.Longtime required tostartnewproduction · Balancingisdifficult4.Significantimpactoffailure · Aproblem in 1machinemakestheentirelinestop.Sohigherimpactoffailure · Toreduceimpactoffailure -> parallelstations - especiallyformachineshavinghigherfailurerate(butlinehas to bebalanced) -> M2.1- min win win aalternative4minSmin4minM. --> M3EntirelinestopsifM2fails. - whenbothMc.12M3.2work-> productevery4winIfM2.2fails - productevery8minbutdoesn'tstop. · Abasicdifferencebetweentransferline&assemblylineisthat,whiletransferlineishighlyautomated,assemblyline requires moreworkforce.So,assemblylineleadtimeisnotdeterministic.-Multi-productmodelnotdiscussed inourcourse. RoughDesignof a Tr a n s f e rLine:(singlemodel)1:Definetechnicalrouting&operationsoftheproducttype · definingtasks/operationstobeperformedfortheproductioncycle · definingvolumetobeproducedStep2: Identifyingmachinetypes&balancingbasedongivenT2.1.Identifyingmachinetypes "¥ singlepurpose -> based on whetherflexibility moreMultipurposeimportantorproductivity. 2.2.LineBalancingii)Defineoperations&sequence(definingpredecessors)required27(iii)computemin no. ofworkstations(iv)Allocatetheoperationstotheworkstations(v)Balancetheline&computetheyvi)AssignmentofpersonnelifanyStep3:CalculatingTheoreticalProductionCapacityTPC = 3600/CT[pc/h]where,CT = cycletime[secs/pcs)ThisPCis considering noproblems or lossesin productionStep4:CalculatingActualProductionCapacityAPC:TPC.A. SR)yield where,A:Lineavailability(OCAC1)SR:Scraprate(OCSRC1)alsobedefectivenessavailabilityofthesystemdepends on theavailabilityofallmachines&transport. --->+ Tr a n s p o r tAlA2AsA4 : A = A,xAcXAzXA4XAtransporthigherthenumberofstations.Levertheavailability, becausehigherchanceoffailure Step5: ComparingAPC&demand · IfAPC-> (i)Reducing no.ofmachinesAl - butTPCL30"30"->Iproductevery30" iii)Increasingno.ofmachinesTPCR->butAd15 " 15"154154->->-> Iproductevery 15 " (iii)UsingparallellinesTPC*Adbuthigherthancase(ii)154Mi->-> M3Aproductevery 15"384->M2.2-So,toincreaseAPC>Addnewmachines->Addparallelstations I-> Changemachinetype:(Machineswithhigherproductivity) ->IntroducePreventive/Predictivemaintenance(IncreasesAl · Preventivemaintenance-based on machinetypesmaintenancedoneaftercertainspecifichours · Predictivemaintenance - usingsensors,realtimeconditionofmachinemeasured&maintenancecarriedoutaccordingly(moreexpensive)(i)To t a lworkcontent,IT:Sumofoperationtimes:T,+T 2 + . . .Th0.1min->0.5min->1min->0.2minITK = 1.8min(ii)cycletime,encalculatedfromproductioncapacityrequired(fromdemandforecast)(iii)timeofthe system:longestprocessingtimeinaworkstation.Example:companyopeninghours - surs/day:480min/dayExpectedproductioncapacity:480units/day:Required (7 = 480/980 = 1minute/unit 0.1->0.7 -- 04 - 0.5->0.2Workstation1 -3 It =0.1minT2tx = 0.1+0.7=0.8minis2tK=1.8minWorkstation2-> TsItk = 0.9min742tK:1.4minWorkstation31T4[tk=0.5minis[tK = 0.7min:workstation,systemcycletime = 0.9min (Station3hashighestprocessingtime = 0.9mil(iv)ofworkstations,Nmin: theoretical minno.ofworkstationsneeded Nmin: 1)Allocatingoperationstoworkstations-I↓Ta s korientedapproachStationorientedapproach NOother Es, (vi)balancing · Assigningtasks toworkstationssuchthatallworkstationshave approximatelyequaltimerequirement · Gualt minimize idletime -> highutilizationrate · constraints - Workloadcan'talwaysbemovedbetweenworkstations · Objectives - Minimizeno.ofworkstations(eastminimization) - Minimizecycletime(productionmaximizath - butrequires more-> Maximizeyworkstations)productioncost -> Maximizeprofit. NinZxTk - NxCT - systemcycletimeLine efficiency: Nxactual no. ofstationsModelsforline balancing: -> linearprogramming(optimall -> Maximum fixedutilizationrate(heuristic) -> notoptimalbutusedbecausesimplerthanlinearprof. -> simplemethod:withoutpriorityrules(eg:alphabeticordersleastused->localpriorityrule:Maxbur(longestprocessingtimeManNFo(largest no.ofimmediatefollowing tasks)->notimmediate -> Globalpriorityrule:MaxFol(largest no offollowingtasks/operations)positionalweighting(positiongivenbased on timetaken) -more precisebut more complex. Approachesforline balancing: -> Ta s kcriented: · whenremainingidletimeinastationisnotsufficientforfollowingtask - opennewstation. · simplerbutlessefficient>Stationoriented · whenremainingidletimeinastationisnotsufficientforfollowingtask -> check ifanyothertaskavailable can beassignedtothestation.When no othertasktobeassigned-closethestation&open anewone· lesssimplebutmore efficient(Checkslidefortherest - fromPo62:Linear Programming (UtilizationRate,UR: Et; whereistimeoftaskiS:setoftasksassigned to theworkstationForeachworkstation,URXwemightwant a utilizationlesswhere, ↑ than100%toallowsomeflexibility.a:manvalueofutilizationrate(0(x