Improvement of logistics in manufacturing system by the use of simulation modelling: A real industrial case study
Abstract
The current practice and the requirements of industrial enterprises in all industrial areas require a detailed display of manufacturing systems course of events. In this paper, we studied the effects and impacts of computer simulation to improve the actual industrial production. We also verified whether the proposed simulation model and its intervention in the logistics of concrete production in a concrete manufacturing enterprise will correspond to reality. The EXTENDSIM simulation software was used. The simulation results utilization in practice has increased the actual production several times. The simulation results indicated that it is necessary to double the intensity of company supply, i.e. a frequency of entry set to 0.15 days for each timber type. This adjustment increased the performance of unutilized devices and the whole manufacturing system several times, up to 54,475 produced building timber elements, which represents an increase of production by about 199.6 % while maintaining company flexibility.
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18 A dvancesinProductionEngineering&ManagementISSN1854‐6250 Volume15|Number1|March2020|pp18–30 Journalhome:apem‐journal.org https://doi.org/10.14743/apem2020.1.346 Originalscientificpaper Improvementoflogisticsinmanufacturingsystembythe useofsimulationmodelling:Arealindustrialcasestudy Straka,M.a,*,Khouri,S.b,Lenort,R.c,Besta,P.d aInstituteofLogisticsandTransport,TechnicaluniversityofKosice,Kosice,SlovakRepublic bInstituteofEarthResources,TechnicaluniversityofKosice,Kosice,SlovakRepublic cDepartmentofLogistics,QualityandAutomotiveTechnology,ŠKODAAUTOUniversity,MladaBoleslav,CzechRepublic dDepartmentofEconomicsandManagementinMetallurgy,VŠB–TechnicalUniversityofOstrava,Ostrava,CzechRepublic ABSTRACTARTICLEINFO The current practice and the requirements of industrial enterprises in all industrialareasrequireadetaileddisplayofmanufacturingsystemscourseo f events.Inthispaper,westudiedtheeffectsandimpactsofcomputersimula‐ tiontoimprovetheactualindustrialproduction.Wealsoverifiedwhetherthe proposed simulation modeland itsintervention inthe logisticsofconcrete productioninaconcretemanufacturingenterprisewillcorrespondtoreality. TheEXTENDSIMsimulationsoftwarewasused.Thesimulationresultsutiliza‐ tioninpracticehasincreasedtheactualproductionseveraltimes.Thesimula‐ tionresultsindicatedthatitisnecessarytodoubletheintensityofcompany supply,i.e.afrequencyofentrysetto0.15daysforeachtimbertype. This adjustmentincreasedtheperformanceofunutilizeddevicesandthe whole manufacturingsystemseveraltimes,upto54,475producedbuildingtimber elements,whichrepresentsanincreaseofproductionbyabout199.6%while maintainingcompanyflexibility. ©2020CPE,UniversityofMaribor.Allrightsreserved. Keywords: Manufacturing; Logistics; Simulation; Modelling; Optimization; EXTENDSIM *Correspondingauthor: [email protected] (Straka,M.) A rticlehistory: Received29September2017 Revised24February2020 Accepted16March2020 1.Introduction Thesolutionofmanufacturinglogisticsproblemsinspecificmarketarearequirestheutilization ofthemeansofalgorithmization,heuristics,mathematicalstatistics, modellingandcomputer simulation.Acombinationofthedefinedapproachesispossibleforthedesigning,anditsolves theproblemsofanymanufacturingsystem.Theobjectiveofthelogisticssolutionsistoinfluence andmanagematerialflowsintherightway.Theexecutionofaconcretemanufacturingsystem fromacomplexpointofviewofalltypesofflowsispossibleonlybytakingadvantageofcom‐ putersimulation.Theapplicationofmathematicalmodellingforthedesigningofmaterial,in‐ formationandfinancialflowstogetherispracticallyimpossible(andwhatabouttheeffectofthe humanfactor,indetermination,haphazardandsoon).Allthesefactsmakecomputersimulation theperfectfacility(inmanytasks,theonlypossibleone)forthesolutionofspecificproblemsof manufacturingsystems.Theforegoingresultsclearlyshowtheimportanceofcomputersimula‐ tionforimprovingtheefficiencyoflogisticsinmanufacturing.Theproblemrelatestoaneffec‐ tiveutilizationofthecomputersimulationwithEXTENDSIMsimulationsystemtoimprovethe efficiency of logistics in manufacturing of concrete productioncompany,engagedinthepro‐ cessingofrawtimberandtheproductionofbuildingtimberintheformofbeams,planks,and boardsfromdifferenttypesofwood,suchasoak,beech,spruceandpine.
Improvementoflogisticsinmanufacturingsystembytheuseofsimulationmodelling:Arealindustrialcasestudy AdvancesinProductionEngineering&Management15(1)202019 Timberproduction,ingeneral,belongstothemostcommontypesofindustrialproductions. Timberasabuildingmaterialisequallypopularinallthecontinentsoftheworld.Themethods ofprocessingrawtimberareidentical,andtheyworkonthesame,respectivelysimilardevices underthesame,respectivelysimilarconditions.Thisimpliestheimportanceoftacklingthisis‐ suefortheindustrialsectorinquestionandtheuniversalcharacteroftheusageofthisapproach toincreasetheefficiencyoflogisticsinmanufacturingbymeansofcomputersimulationandthe EXTENDSIMsimulationsystem. Theaimofthispaperistoclearlydefineaprocedurewhichmustbefollowedtosolveequal orsimilartypesoftasksthroughtheutilizationofconcreteEXTENDSIMsimulationsystemserv‐ ingtheneedsofindustrialpractice.Thetasksthatmustbeexecutedarerelatedtosomegiven resolutionproceduresthataregenerallyapplicabletostreamlinethelogisticsinmanufacturing usingcomputersimulation.Thequalityofthesolutionsandtheirimpactsonthemanufacturing systemdependonthequalityoftheperformedanalysis,qualityandaccuracyofdataacquired forthepurposeofthesimulationmodel,andtheknowledgeandexperienceofthecreatorofthe simulationmodelwiththeworkwithaconcretesimulationsystem. The subsequent correct evaluationoftheresultsandthedefinitionofconclusionsfortheimplementationofmeasuresin practiceareequallyimportantaswell. 2.Literaturereview Inordertobeabletounderstandtheessenceofthefunctioningofthemeansofsimulation,itis necessarytodefineandunderstandthebasicprinciplesandrelationsofsimulationandmodel‐ lingandthepartsconcerned.Thegoalofasimulationistoobtaininformationaboutthesystem anditselementsaccordingtopresumedordefinedchangeofcharacteristicsoftheelementsand theirconnection. Asimulationofthesystemsmakesitpossibletoexperimentbesidesrealobjects,resp.these objectsdonothavetoexist.Simulationasatermmeansanimitation ofsomereal situation, thing,condition,action,eventofprocess[1,2].Simulationisaresearchmethod,theessenceof whichconsistsofthereplacementofanessentialdynamicsystembyitsmodel,simulator,and weperformexperimentswiththepurposeofgettingtheinformationabouttheessentialsystem. Usingasimulation,itispossibletoobtainanswerstosomeveryimportantquestions,suchas: “Howisthesystemgoingtobehavewhenthefollowing(any)changeshappen?Whichpartofthe systemcontainscriticalpoints?Howlongisthedistancetheconveyormustovercomeiftwo morestationsareaddedinthesystem?Howlongwillittaketoruntheproduction?Howmany peopleareneededtomeetthedeadlineoftheproject?”.Inasimplifiedway,itispossibleto characterizesimulationbythreesteps: designofthesimulationmodelofarealsystem, carryingouttheexperimentswiththesimulationmodel, reverseduseoftheobtainedresultstoimprovethesystem. Inourview,theobjectsofthesimulationwillbeproductionprocessesrepresentingthepro‐ cessesinthegroupofaggregates,machinesanddevices,onwhichtheproductionprocessesare progressing.Theamountoftheproductionoperationsdependsonthetypeofproductandon theuseddevices,onwhichtheproductionoperationsaretakingplace.Continuousproduction processesaretheprocessesleadingtoasmooth,continuouschangeofthestateoftheproduc‐ tionprocess(workofthebreaker,mills,andconveyorbelts).Discrete(discontinuous)produc‐ tionprocessesaretheprocessesleadingtoachangeofthestateoftheproductionprocessat certaintimemoments(transportofmaterialbycars,wagons,loadingofmaterialsbyanexcava‐ tor).Combinedproductionprocessesarecharacterizedbycombiningthediscreteandcontinu‐ ousproductionprocesses(transportofmaterialbycarsfromquarryintoaballcrusher). Theoriginsofthe creation ofsimulationmodels goes backtothe1950’s,whenuniversal, generalprogrammingsystemswereusedtocreatesimulationmodels.Agradualdevelopment andprogressiseveryareaofproduction,scienceandpracticerequired increasingly difficult
Straka,Khouri,Lenort,Besta 20AdvancesinProductionEngineering&Management15(1)2020 simulationmodelsandapplications.Generalprogrammingsystemsprovedtobemaladroitand notdynamicenoughtocreatefastchangesinthesimulationmodels.Aspecialcategoryofpro‐ grammingsystemshasgraduallybeeninvented.Thesesystemsarecalledsimulationsystems. Simulationsystemsareadaptedforthepurposesofsimulation.Theyallowustocreateprogram simulationmodelsinsuchformtocreatemodelsrepresentingthesimulatedsystems[3‐5].The simulationmodelsallowustoperformquickchangesinthecreatedmodels,incasetheyare needed,insuchawaythatthecreatedmodelscorrespondtothechangesthatcanoccurinareal system. Theevolutionalphasesofthesimulationsystemschangeintimeandnaturallyevolve[6].The recentstateischaracterizedbyobjectandrealisticallyorientedsimulationwiththesupportof 3Danimationsandvideoonaprofessionallevel.Accordingtothefunctionalaspectsofthesimu‐ lation,simulationsystemsareorientedtoactivities,eventsandprocesses,whereinachangeof statecanoccurcontinuously,discretelyorinacombinedform[6‐8]. Eachareaofproblemsolvingrelatingtologisticscombinesandusestherequiredmethodology, methods,proceduresandtoolsspecifictothegivenarea,butalsothemethodsofotherareas. Thevariabilityofsomesolutionswithinthelogisticsclearlypredeterminestheusageofmethods basedontheprincipleofmulti‐criteriadecision‐making,statistics,modelling,theprinciplesof heuristicsandcomputersimulation[9‐11]. Toachievethehighestperformancewithmaximumproductionefficiency, logistics, from the strategic, tactical and operational levels, defines respectively proposes actions that lead to achievementoftherequiredresultsbyusingalltheavailablemeansofscienceandtechnology, economicsandcomputerscience[12,13]. Theaimoflogisticsistocreateaunited,integrated,optimizedmaterialflow,whichisarisen fromdifferentpartsofthesysteminthewaytoensureacontinuousexchangeofgoodsandser‐ vices[14].Logisticshasgraduallybeendevelopingandmanydefinitionshavealsobeendevel‐ opedtogetherwithit,whilenewperspectivesonitsscopeanditslevelofactivityarestillbeing formed.AccordingtoHesket,GlaskowskyandIvie[15],logisticsisthemanagementofallactivi‐ tiesthatfacilitatethemovementandcoordinationofofferanddemandincreatingoftimeand placebenefits.AccordingtoSchulte[16],logistics is anintegrated, market‐orientedplanning, creation,implementationandcontrolofflowsofmaterial,goods,informationfromsuppliersto enterprises,inenterprisesandfromenterprisestoclientsatoptimalcosts.AccordingtoMalin‐ dzak[17],logisticsistheway,philosophyofflowsmanagement(material,informationandfi‐ nancial), at which there are applied systematic approach, methods of planning, algorithmic thinkingandcoordinationinordertoachievetheglobaloptimization.AccordingtoStraka[18], logisticsisasysteminwhichthereisanaffecttoelementsinordertosetcoordinatedmaterial, informationandfinanceflow,resultingin,respectively,aimingatsatisfyingcustomerrequire‐ ments and respective economic effect. According to Merkuyev, Merjuyeva, Piera and Guasch Petit[19],simulationmodelshaveprovedtobeusefulforexaminingtheperformanceofdiffer‐ ent system configurations and/or alternative operating procedures for complex logistic and manufacturingsystems.Itiswidelyacknowledgedthatsimulationisapowerfulcomputer‐based toolenablingdecision‐makersinbusinessandindustrytoimprovetheirorganisationalandop‐ erational efficiency. Combining simulation with experimental design or intelligent search has beensuccessfullyadoptedforsimulationoptimization[20,21]. Logisticsasascientificdisciplinewasfirstdefinedbackinthe50s.Subsequently,therewas thedevelopmentoftheMRPI–MaterialRequirementsPlanningsystem.Laterinthe60’s,the MRPII–ManufacturingResourcesPlanningsystemwascreated,wheretheoriginalMRPwas supplemented by the algorithmsfor capacity calculations [22]. In the 70s, the method called Just‐in‐timewasdiscoveredforthefirsttime.Duringthe80’s,theadvancementsincomputer technologyhelpedtoacceleratetheinformationflows.Later,fullyintegratedlogisticssystems graduallystartedtoemerge,whichresultedincostsavingsandgradualreplacementofmanual workbymechanisation[23,24].Theareaoflogisticscoversavarietyoftechnicalmeans,suchas theelementsofconventionaltransport,theelementsofproductionfacilities,robots[25‐27]and, recently,alsomoderndrones[28].
Improvementoflogisticsinmanufacturingsystembytheuseofsimulationmodelling:Arealindustrialcasestudy AdvancesinProductionEngineering&Management15(1)2020 21 3.Presentationoftheproblem The investigated company is focused on timber processing of production of building timber products,suchasbeams,planksandboards.Theyarecurrentlyverypopularfortheconstruc‐ tionoflowcosthousesthecoreofwhichisformedfrombeams,planksandboards.Thatiswhy thereisahighdemandfortheproductsofthecompanyfortheneedsofthebuildingindustry. Thebasicelementoftheproductsofthecompanyistimber.The company produces beams, planksandboardsoftherequireddimensions andtypesbymeansoftimbercutting, edging, planning,millingandtrimming.Therawmaterialissuppliedfromvarioussourcesandthemain typesofwoodsareoak,beech,spruceandpine.Allthetypesofrawtimberfortheproduction companiesarerepresentedinthesamevolume.Thesupplytheproductioncompanyiscarried outbythecontractedtransportcompaniessupplyingonetruckoftimberofeachtimbertype onceaweek. Thedescribedproductioncompanyhasitsheadquartersinthesouth‐eastofSlovakiainthe vicinityofKošicecity.Thecompanyprovidesacomplextimberprocessing,i.e.fromtheinputsof raw timber through its storage, cutting and drying, to manufacturingofbeams,planksand boards.Thewastegeneratedduringtheproductionisprocessedinacontractingcompanyto producepelletsandwoodchipsusedforheating. Asthereisanincreasingdemandfortheproductsofthecompany,whichisdemonstratedby theincreaseinthebuildingactivitieswithintheregion,therearesituationsduringwhichthe companyisnotabletomeetalltherequirementsofthemarketintheshortterm.Thisisalsothe reasonwhythecompanyisinterestedinidentifyingthebottlenecks[29]inproductionandde‐ signofthelogisticsinmanufacturinginordertoproduceandpurchasenewdevicesthatcould increasetheirproductionwithaminimuminvestment[30‐32].Theentireproductionprocessof rawtimberprocessingwasdevelopedtoitspresentformonlybasedontheexperienceofthe companyoperatorsandworkers.Sincewooddryingisthelongeststageintheprocessingofraw timberintermsofthetechnologicalprogress,thecompanyboughtadryingkilnforthebatch dryingofwoodmaterial.Thecapacityofthekilndryingdeviceis40m3.Dryinginthisdevice takes50daysonaverage,accordingtothetypeandthicknessofthewoodenelements.Within thetechnologicalprocess,therawtimbermaterialisgraduallyshiftingthroughtheworkplaces: receivingrawtimbermaterialanditsstorage–cuttingheadsaw–edgingsaw–wooddrying– crosscutsaw–planning,milling,trimming–productsdespatch(Fig.1).Cuttingswasteispacked intosacksatspecialworkplaceforthedisposalofwaste. Fig.1Schemaofthecompanylogisticsinthemanufacturingsystem Capacityutilizationofthedevicesisperformedbymeansofthepreparationofrawtimber,its dryingandthecrowdednessofthesysteminadvance.Thepassage time through the timber manufacturingsystemdependsonthecapacityoftheindividualdevices,theircadenceandthe timenecessaryfortheexecutionofthemanufacturingoperationandoverloadingofthemanu‐ facturingsystemasawholeunit(Table1).Statistically,mostofthetimeinrealoperationisre‐ quiredfordryingoftherawtimbermaterial.Thecompanyprovidestransportoftheproductsto customersbymeansofoutsourcingcompanies. Eachworkstationisequippedwithitsownbuffernecessaryfortheregulationofdifferent productioncapacitiesandtoensurethefluencyofproduction.Ineachpartofthetechnological process,itisnecessarytohaveanenoughsemi‐finishedtimberelement.Thatiswhyasignifi‐ cantamountofsemi‐finishedproductsandunfinishedtimberelementsisboundineachpartof thesystemandasignificantamountofcapitalisboundinwarehousing,resourcesandinsemi‐ finishedproducts.
Straka,Khouri,Lenort,Besta 22AdvancesinProductionEngineering&Management15(1)2020 Table1Parametersofworkstationsdelay,anddevicesdelayinlogisticsinmanufacturing Timber Timber entry Cutting head resaw Edging saw Kiln drying Air seasoning Cross cut saw Wood planning Wood milling Wood trimming Packing cuttings waste Oak 3pieces /day/ type 60min 3.5min 75days 6months 2min 5min 15min 5min 5‐8min Beech 60min 3.5min 75days Spruce 40min 3.0min 25days Pine 40min 3.0min 25days 4.Materialsandmethods Thenextstepisapreparedcomprehensivesimulationmodelofalltheactivitieswithinthetim‐ bermaterialprocessing,whichrequiredathoroughanalysisandcompliancewiththestepsfor‐ malizedscheme:descriptionofproductionunits,blockdiagram,simulationmodel,simulation runs,improvementofefficiencyoflogisticsinmanufacturing. 4.1Thecreationofaformalizedscheme Tomakethecomputersimulationmodel,thefirstrightstepistocreateaformalizedscheme thatrepresentstheexactsequenceofproductionoperations,interconnectingfacilitieswiththe technicalresourcesofthecompany.Thisstepalsoinvolvesretrievingtheinformationaboutthe parametersofthematerialflowsintermsofvolumedistributions.Suchaformalizedscheme thenrepresentstheoverallsystemwithitsfeaturesandlinks.Inthiscase,thesystemconsistsof theindividualelementsrepresentedbytheoperationswithtimbermaterial.Betweentheopera‐ tions,therearelinksformedbytheelementsofflowmanagementofsemi‐finishedproductsand oftimberwaste.Aformalizedstructure(Fig.2)isaveryimportantbasisforthecreationofan actualsimulationmodel.Thelimitationsandcapacityoftheproductionfacilitiesareimportant forcorrectunderstandingofwholesystemactivityandtheelementsoflogisticsinmanufactur‐ ing.Duringthesubsequentsimulationmodelling,theindividualpartsofaformalizedscheme willbereplacedbyarespectiveblockofspecificsimulationsoftware.Delayparameters(Table 1)arecrucialforthesettingofthesimulationmodelblocksandforthecontrolandsolutionof thecriticalproductionbottlenecksofthewholemanufacturingsystem. Fig.2Theformalizedschemeofbuildingtimberelementsproduction 4.2Thelogisticsinmanufacturingunits Theentiremanufacturingsystemandlogisticsinmanufacturingiscomposedofpartsthatare arrangedinsequenceaccordingtothetechnologicalprocedure.Thesystemismainlyseriesori‐ entedwiththefinalprocessingofproductsaccordingtotherequiredprocesses.Thesequenceof productiontechnologyisdeterminedbythearrangementofspecializedworkplaces,whichare createdbyworkplaceforincomeandstorageofrawtimbermaterial,workplaceforcuttinghead resaw,workplaceforedgingsaw,workplacefordryingtimber,workplace for cross cut saw,
Improvementoflogisticsinmanufacturingsystembytheuseofsimulationmodelling:Arealindustrialcasestudy AdvancesinProductionEngineering&Management15(1)202023 workplacesofproductsfinalizationaswoodplanning,woodmilling,woodtrimmingandwith workplaceforpackingofcuttingswaste. Theworkplaceofincomeandstorageofrawtimbermaterialensuresthesupplyofthecom‐ panywithrawtimbermaterial,anditsprimarystoragebythetypeoftimberbeforeprocessing. Thecompanysupplyiscarriedoutonaweeklybasiswithafrequencyofonetruckforeachtim‐ bertype,whichrepresentsabout20‐24unitsofonetimbertypeperweek,i.e.approximately1 pieceoftimbermaterialper0.33day. Theworkplaceofcuttingheadresawinvolvesrawtimbermaterialcutting(dependingonthe thicknessandlengthoftimber)tobeams,planksandboards.Theoutputofthecuttingisrepre‐ sentedbyunedgedtimberelements.Theprocessingtimeoftheelementsdependsonthetypeof timber.Thecuttingprocessofonetimberpieceofoakandbeechrequiresabout60minutesand thecuttingprocessofonetimberpieceofspruceandpinerequiresabout40minutes.Theaver‐ ageoutputaftercuttingis20piecesofvariouswoodenelementsintheformofbeams,planks andboards.Thecuttinggenerates10%ofcuttingswasteand90%ofwoodenelementscon‐ tinuingtothenextworkplace. Theworkplaceofedgingsawisusedforadaptingandedgingofunedgedwoodenelements. Thetimeforedgingofwoodenelementsdependsonthetypeoftimber,butanaveragetimefor oaksandbeechesedgingisabout3.5minutes,andforspruceandpineedging,thetimeisabout 3minutesforonepieceofwoodelement.Theedgingofwoodenelementsproduces25%ofcut‐ tingswaste.Afteredgingofthewoodenelements,10%issoldintherawstateand90%ofthe elementswillbemovedtotheworkplaceofwooddrying.10%goestothekilndrying,and80% isdriedintheopenstockinnaturalconditions. Thekilndryingdevicehasacapacityof40m3foradryingbatch.Thecutrawtimberisdried accordingtotherequirementsforthepercentageofmoistureandforthetypeofmaterial.In general,therawtimbermaterialsoftheoakandbeechtypesaredryingforabout75daysand thespruceandpinetypesaredryingformabout25days.Dryingoftherawtimbermaterialat theopenstockinnaturalconditionstakesaboutsixmonthsforallthetypesoftimber. Afterdrying,thetimberelementsarecuttotherequiredlengthsattheworkplaceofcrosscut saw.Thetimefortimberelementscuttingtotherequiredlengthsisabout2minutesperone pieceoftimberelement.Thecuttingprocessgeneratescuttingswaste,whichrepresents10%of thetimbermaterialcapacity. Aftercutting,65%ofthetimberelementsarereadyforsaleandexport,and35%ofthetim‐ berelementsaretreatedaccordingtospecialrequirementsofcustomersattheworkplacesof woodplanning,woodmillingandwoodtrimming.Theworkplacesofwoodplanning,woodmill‐ ingandwoodtrimmingprovideaserviceforcustomersandtheirrequirementsforthefinalma‐ chining.Theprocessingtimeofthewoodplanningandwoodtrimmingisabout5minutesfora onepieceofanytypeoftimberelement.Theprocessingtimeof wood milling is about 15 minutesforaonepieceofanytypeoftimberelement.Allthefinalactivitiesproduce5%ofcut‐ tingswaste. Allthetimberwasteissituatedinthestockofthepackingofcuttingswasteworkplace.The packingofonewasteunitrequiresabout5‐8minutes.Wastetakingiscarriedoutbyacontract‐ ingfirmanditsownmeansoftransport.Cuttingswasteisusedforthesecondaryrecoveryand forheating. 4.3Themodeloflogisticsinmanufacturingrepresentedbyablockdiagram Tocreateablockdiagram(Fig.3)asabasisfortheactualsimulationmodel,itisimportantto preparethedataandtheinformationthatareessentialforthesettingoftheindividualblocks withinthesimulationmodel[33].Fromthestatisticaldataobtained from observation and measurementinthefieldaswellasfromthetechnicaldocumentationdata[34],itappearsthat theinputofthetimbermaterialintosystemoccurseach0.33day,whenanotherpieceoftimber materialentersthesystem.Inthesimulationmodel,thisismodelledbythefourentryblocks "create"foreachtypeoftimberwithaconstantdistributionsettingof0.33day.Justbeforethe firstproductionfacility,whichisthecuttingheadresaw,thereisanunprocessedtimberstorage whichbalancesthecadencedelayswithinproductionandthecapacityofthecontrolunit.Inthe
Straka,Khouri,Lenort,Besta 24AdvancesinProductionEngineering&Management15(1)2020 simulationmodel,thisisrepresentedbyfourblocks"queue"withthesettingof"lastinfirstout (LIFO)",materialisputonitself.Afterthat,thereisacuttingheadresawtypeofdevice,where theprocessingofasinglepieceoftimberrangesfrom40to60minutes.Inthesimulationmodel, thisdelayismodelledbya“lookuptable”withconstantdistributionwithdelayparametersset to40minutesor60minutesfortheprocessingofonepieceandtypeoftimber. Fig.3Blockdiagramofthebuildingtimberelementsproduction 4.4ThelogisticsinmanufacturingoftheconcretecompanydesignedbytheEXTENDSIM Eachrealactivity,andalltheprocessesandoperationsofthemanufacturingsystemareneces‐ sarytotransformanddesignbytheblocksofconcretesimulationsystemEXTENDSIM.Partsof theformalandblockdiagramswillbetranslatedstepbystep,blockbyblocktoEXTENDSIM simulationmodel.Theentryoftimberintotheproductioncompany,theidentificationoftimber typesandthestorageoflogsarerepresentedbytheblocksof"create",“set”and"queue"(Fig.4). elblocksand forthe control andsolution ofthe critical productionbottlenecks ofthe whole manufacturingsystem. Theplaceofworkof“Cuttingheadresaw”ismodelledinthesimulationmodelusingthefirst “hierarchyblock”.Thehierarchyblockforthisoperationiscreatedusingtheblocksof“activity” –“batch”–“selectitemout”(Fig.5). Fig.4Blocks"create",“set”and"queue"whichrepresenttheentryoftimbermaterialintothecompany, theidentificationoftimbertypeandthestorageoflogs
Improvementoflogisticsinmanufacturingsystembytheuseofsimulationmodelling:Arealindustrialcasestudy AdvancesinProductionEngineering&Management15(1)202025 Fig.5Blocksof"hierarchyblock",“activity”,“batch”and"selectitemout"whichrepresentthecuttingof thetimberintosemiproductssuchasbeams,planksandboards Theplaceofworkof“Edgingsaw”ismodelledinthesimulationmodelusingthesecond“hi‐ erarchyblock”.Thehierarchyblockforthisoperationiscreatedusingtheblocksof“selectitem out”–“queue”–“selectitemin”–“activity”–“selectitemout”(Fig.6). Fig.6Blocksof"hierarchyblock",“selectitemout”,“queue”,“selectitemin”,“activity”and “selectitemout”whichrepresenttheoperationedgingofthetimber Theplaceofworkof“Wooddrying”ismodelledinthesimulationmodelusingthethird“hi‐ erarchyblock”.Thehierarchyblockforthisoperationiscreatedusingtheblocksof“selectitem out”–“queue”–“selectitemin”–“selectitemout”–“batch”–“activity”–“selectitemin”(Fig.7). Fig.7Blocksof"hierarchyblock",“selectitemout”,“queue”,“selectitemin”,“selectitemout”,“batch”, “activity”and“selectitemin”whichrepresenttheoperationdryingofthetimber Theplaceofworkof“Crosscutsaw”ismodelledinthesimulationmodelusingthefourth “hierarchyblock”.Thehierarchyblockforthisoperationiscreatedusingblocks“selectitemout” –“queue”–“selectitemin”–“activity”–“selectitemout”(Fig.8). Bycombiningtheabovedescribedsimulationmodelelements,severalselectedproduction processesweremodelled,andtheyrepresenttheactualreal‐lifemanufacturingsystemwithin theinvestigatedcompany(Fig.9).
Straka,Khouri,Lenort,Besta 26AdvancesinProductionEngineering&Management15(1)2020 Fig. 8 Blocks of "hierarchy block", “select item out”, “queue”, “select item in”, “activity” and “select item out” which represent the operation cross cutting of the timber Fig.9Thesimulationmodeloftheresearchedcompanybuildingtimberproduction 5.Results Asthesimulationresultsindicate,thedryingplaceofwork,namelythefacilityfordryingoftim‐ bermaterialistheactualbottleneck.Thegivenstateisderivedfromthesimulationanalysisand hasbeenverifiedbythetechnologymanagementofthecompany.Thefindingsindicatethatthis placeofworkisnotsufficientlyefficienttoprocessthetimbermaterialenteringthedryingpro‐ cess,whichresultsinanaccumulationofunprocessedmaterial(Fig.10).Thisstageissolvedby meansofdryingthetimbermaterialbyairseasoning.Thisprocessofdryingisextendingthe timenecessaryforprocessingoftimberinthemanufacturingsystem and possibly results in gradualdegradationofqualitytimbermaterialandofthecompanyresources. Thesimulationresultsindicatethatthecompanyproducedatotalofapproximately18,000 buildingtimberelementsforoneyear.Themostsoldbuildingtimbermaterialsofthecompany duringtheyeararethedriedandmadetomeasurebeams(4,800pieces),planks(3,309pieces) andthedriedbeamsofvarioussizes(1,734pieces).Theutilizationofworkstationswoodplan‐ ning,woodmillingandwoodtrimmingdoesnotexceed10%,evenaftertheoptimization.To increasetheutilizationoftheplanning,millingandtrimmingequipment,theproductioncompa‐ nymustoffertheseprocessesusedforthefinalizationofwoodelementsasaserviceprovidedto itscustomers.Thisactivitycanattractnewcustomersforproduction.