JOURNAL OF ENGINEERING MANAGEMENT AND COMPETITIVENESS (JEMC)Vol. 5, No. 2, 2015, 55-60KANBAN SIMULATION MODEL FOR PRODUCTION PROCESSOPTIMIZATIONUDC: 658.5Original Scientific PaperRiste GOLCHEV1, Bojan JOVANOSKI2, Valentina GECHEVSKA1, Robert MINOVSKI11Ss. Cyril and Methodius University in Skopje, Faculty of Mechanical Engineering, Department of IndustrialEngineering and Management, 1000 Skopje, Karpos II bb, Republic of Macedonia.2Ss. Cyril and Methodius University in Skopje, Faculty of Mechanical Engineering, Department of IndustrialEngineering and Management, 1000 Skopje, Karpos II bb, Republic of Macedonia.E-mail: [email protected] received: 30.10.2015.; Paper accepted: 21.11.2015.A long time has passed since the KANBAN system has been established as an efficient method forcoping with the excessive inventory. Still, the possibilities for its improvement through itsintegration with other different approaches should be investigated further. The basic researchchallenge of this paper is to present benefits of KANBAN implementation supported with DiscreteEvent Simulation (DES). In that direction, at the beginning, the basics of KANBAN system arepresented with emphasis on the information and material flow, together with a methodology forimplementation of KANBAN system. Certain analysis on combining the simulation with thismethodology is presented. The paper is concluded with a practical example which shows thatthrough understanding the philosophy of the implementation methodology of KANBAN system andthe simulation methodology, a simulation model can be created which can serve as a basis for avariety of experiments that can be conducted within a short period of time, resulting withproduction process optimization.Keywords: KANBAN, manufacturing, simulation, methodology for KANBAN implementation, processoptimization.INTRODUCTIONThere is no doubt that the Japanese managementprinciples, philosophies, methodologies andmethods had a deep impact on the functioning oforganizations in general, (Ohno & Bodek, 1988;Pisuchpen, 2012; Sugimori & Kusunoki, 1977).Toyota Production System (Monden, 1998), is themain frame of those approaches. KANBAN as apart of JIT (Welgama et al., 1995) is probably oneof the most famous parts of the Toyota ProductionSystem, since it directly copes with the waste ofcreating extra inventory, affecting and reducing allother wastes in production. It is also a fact thatacceptance of those approaches in the companiesin underdeveloped countries is not on the desiredlevel. On the other hand, they are facing seriousproblems concerning the insufficient or excessiveproduction, on time delivery, generating extrainventory etc. In general, companies have issuescoping with the management of the overallproduction processes. Furthermore, managers areoften conservative when changes in theirmanagement concepts are the topic of discussion.Namely, it is more than clear that implementationof KANBAN is accompanied by seriousprerequisites for its implementation: detaileddesign of processes, standardization of theoperations and smooth production, (Monden,1998). Fulfillment of these prerequisites needshuge investment in all kind of resources, leading tosignificant time and money expenditure. This isfrequently a reason for leaving the initial idea forKANBAN implementation. This article is based ona basic research for possibilities for KANBANimplementation in one metal-working company. Inthat direction, the basic aim of the article is topresent benefits of combined implementation ofKANBAN system and methodology for DiscreteEvent Simulation (DES). After giving the brieftheory on KANBAN and DES, the article discussesthe options for their integration. The case at theISSN 2217-8147 (Online) 2015 University of Novi Sad, Technical faculty “Mihajlo Pupin” in Zrenjanin, Republic of SerbiaAvailable online at http://www.tfzr.uns.ac.rs/jemc
56Golchev et al.end is focused on one production line in one metalmetalworking company and experiments with thecontainer capacity which directly affects thenumber of KANBANs.KANBAN PHILOSOPHYThe word KANBAN comes from two Japanesewords: KAN- Signal and BAN-CardCard or Board,hence KANBAN is considered to actually be asignal card. KANBAN is defined in the followingway:The KANBAN system represents theinformation system JIT (Just in Time), whichprovides management of the production flow inthemanufacturingprocessintherequired/needed quantities for each processprocessneither too many or too little of the neededproducts, (Minovski, 2007).KANBAN Card Type – PProduct TypeContainer TypeContainer capacityStorage locationPrevious ProcessNext ProcessProduction cyclePlannerReleased onThe basic information carrier within the KANBANsystem is a rectangular card, enveloped in a plasticcase, called a KANBAN card,card Figure 1. TheKANBAN card is always attachedtached to the containerthat contains the parts for which the card isintended. For this paper, the information stored inthe “Container capacity” field is of crucialimportance for the process and the simulationmodel.The KANBAN system represents a pulling systemand its mechanism moves the information in theopposite direction from the next work station,while the materials move conversely from theinformation of the previous work station to thenext one, aided by the KANBAN cards. A genericscheme with only two working stations ispresented in Figure 2. The same concept can betransferred to n working stations.Id. No. 35/2015Metal cabinetMetal, 2 x 1 m35A–2Machine processing – CNC lathePunching3 daysR. G.25/03/2015Figure 1: KANBAN cardLödding, 2013)2013Figure 2: Information and material flow in the KANBAN system (Lödding,
JOURNAL OF ENGINEERING MANAGEMENT AND COMPETITIVENESS (JEMC)When the client takes the pulled product, theKANBAN card moves in the opposite direction,towards the KANBAN board on Work Station 2,signalizing that the reproduction of the pulledproduct should begin. In order to make the pulledproduct, the operator on Work Station 2, pullsmaterials from Work Station 1, and the KANBANcard for those materials moves to the KANBANboard on Work Station 1, allowing thereproduction of the pulled material to begin onWork Station 2.IMPLEMENTATION OF KANBAN SYSTEMMETHODOLOGYOne possible methodology for the purpose ofsystemized and easier implementation of theKANBAN system is presented, consisting of sevenfundamental phases as shown in the flow chart inFigure 3.Data Collecting andAnalysisNoKANBAN numbercalculationDesigning ofKANBANIs KANBAN designedproperly?57to mention expensive, calculations and iterationsmust be made, (Müller et al., 2012).There are number of possible tools in order todetermine the best KANBAN system, but also toexperiment with it. One of them is the simulationand its advantage in experimenting with andoptimizing performance values. Since there aremany variables to experiment with, the simulationshortens the time needed to determine the possibleoutcomes of the system in different situations,(Hao & Shen, 2008). For the most part, simulationsare more than useful in the first three steps of themethodology, especially in the third one, duringthe actual design of the KANBAN system. Thispaper is focused on these three steps. As it wasstated before, the simulation was used in order todetermine the capacity of the container, or thenumber of KANBAN cards needed in order toachieve a more effective production process.The creation of the simulation model shown belowis based on the methodology according to (Bankset al., 2004) a methodology that offers asystemized approach. As a result of thecharacteristics of the methodology and because itssteps are not strictly successive, it allowsadjustments to different application. Because of thespace limitation of the paper, not all methodologysteps are explicitly presented.KANBAN SIMULATION MODELYesTrainingStarting the KANBANsystemMaintenance andaudit of the systemImprovement of thesystemFigure 3: Methodology for KANBANimplementation (Gross & McInnis, 2003)This presented methodology seems fairly simple;however, its implementation is a challenge,because in order to be certain that the KANBANsystem is well-designed, a variety of stochastic, notThe following part presents the application of theKANBAN system in a simulation model madewith the software suite Technomatix y, each and every problem is definedduring the first step. Then, goals are set and amodel is conceptualized according to the acquiredinformation. After formulating the model,experiments which in normal circumstances mightlast for days, months or even years are created injust few minutes. If after the result analysis it isconcluded that the experiment data are sufficientand correct, records are prepared and the final step,implementing the solution, can be made.Defining the problem: Unbalanced ProductionAlthoughinfluencesthroughoutshould beassociatedproduction.the KANBAN system indirectlythe resolutions of many problemsthe entire production processes, itnoted that KANBAN is commonlywith overproduction or unbalanced
58Golchev et al.Purpose of the simulation model: Determiningoptimal KANBAN container capacity inrelation to the demandit. Furthermore, the storage units are an additionalburden when it comes to space usage. In order toavoid the main and the biggest problem (to avoidoverproduction) it is immensely important todesign a precise KANBAN system.The purpose of this simulation model is throughsimulation of a number of possible productionscenarios with previously determined settings, toget an optimal capacity of a KANBAN container,in relation with the daily needed throughput. Thisis extremely important because the containers arethe ones that when empty, initialize the beginningof the production, and when they are full they stopFigure 4 shows the basic concept of setting theelements in the simulation model, (Robinson,2004). The information moving direction, as wellas the direction of the product can be clearlynoticed on the figure, starting with the rawmaterials and ending in the hands of the customer.Figure 4: Basic concept of the simulation modelThe following basic settings for the simulationmodel are set: Processing time for CNC lathe and Packagingstation 1 minute 100% availability Dismantle station: Station where the productsare separated from the containers withsuccessor 1 Empty container 0 with successor 2 Customer: The place where the final productsleave the system 1 simulation cycle 3 work shifts * 8 hourshiftsThe production flow is defined as follows:The container is located on the Dismantle stationwhere it is gradually emptied. If the container isempty (Empty container 0), it will be transferred tothe spot for P.S. Finished parts. The container’sarrival signalizes the need for the beginning of theSemi-Product processing. This occurs in such amanner that the now empty container from the spotP.S. Semi-Products is transferred to the spot CNCFinished Parts, where it receives the final productsfrom CNC Finished Parts to Empty Container 1.The Container and parts merge (filling thecontainer with parts) and it takes it back to the spotCNC Lathe Semi-Product. The arrival of thecontainer initializes the beginning of production onthe CNC Lathe. If the CNC Lathe finished partscontainer is full, the container will be sent to thespot for Semi-Products on P.S. Semi product. Thefinished products from the Packaging station willthen be sent to the Dismantle station. TheKANBAN containers are the ones that initializeand control the beginning and end of theproduction process. KANBAN containers containall the needed information in this simulationmodel.EXPERIMENTAfter the simulation model presented in theprevious chapter is verified and validated, the nextstep entails conducting experiments and analyzingits outcomes.
JOURNAL OF ENGINEERING MANAGEMENT AND COMPETITIVENESS (JEMC)In Figure 5,, the results of simulating 13 differentcycles are presented. Thehe ordinate lists the dailythroughputs done in 3 shifts, 8 hours each,each whilethe abscissa shows the values for which theKANBAN container is limited.First,, it can be noticed that by decreasing thecontainer’s capacity, daily throughput does notdecrease proportionally. Instead, there areoccasions when a container with different capacity,has identical daily throughputs. Thus, if theproduct demand is projected to 750 finished partsby the end of the day, there are two differentpossibilities for choosing the container capacity.The first possibility is to choose a container withcapacity of 75 parts per container, and the other is50 parts per container.r. For this specific case, it is59better to choose the second option becauselogically,, this type of container has higher numberof daily cycles. The higher number of cyclesreduces the processing time per container. Thismakes the system more flexible and resistant toexternal disruptions including change in demand,defects, change of the product etc. Mostimportantly, with this type of container, wheneveran error occurs, less number of parts will beaffected by it.It is the same when the needed daily throughputthis720 finished parts per day. Furthermore, thissimulation model can be a perfect basis for futureexperiments. These can include other importantfactors, such as: delays, defects, scrap percentage,product changes,, workers overload etc.Figure 5: Experiment resultsCONCLUSIONThe main goal of every organization is to alwaysdesign optimized processes. These processesshould be implemented wasting minimum money,while focusing on the client’s needs.Hence, it can be concluded that KANBAN is theright tool for creating such processes.cesses. On the otherhand, the simulations can be utilized as a tool forfast and reliable designing of the KANBANsystem. The researchesearch presented in this article dealswith the decisions on what and when needs to beproduced, having in mind the lowest possibleposscostsfor transport, storage, control etc. Moreover, in thispaper, it is clearly shown that with the aid of asimulation package, engineers can make simulationmodels which shorten the time for designing,planning and analyzing possible outcomes of thetKANBAN system implementation.The simulation model discussed in this paperopens new horizons and opportunities formanagers, offering them ideas on how to improvethe productivityoductivity of their companies.REFERENCESBanks, J., Carson, J., Nelson, B. L., & Nicol, D. (2004).Discrete-EventEvent System Simulation (4th Edition):Edition)Prentice Hall.Gross, J. M., & McInnis, K. R. (2003). Kanban MadeSimple: Demystifying and Applying Toyota'sLegendary Manufacturing Process:Process AMACOM.Hao, Q., & Shen, W. (2008). Implementing a hybridsimulation model for a Kanban-basedKanbanmaterialhandling system. Robotics and Computer-IntegratedComputerManufacturing, 24(5),(5), 635-646.635doi:10.1016/j.rcim.2007.09.012Lödding, H. (2013). Handbook of ManufacturingControl. Fundamentals, description, configuration.Berlin: Springer.Minovski, R. (2007). Management Information Systems.SystemsSkopje: UKIM.Monden, Y. (1998). Toyota Production System: AnIntegrated Approach to Just-In-Time:JustChapman &Hall.
60Golchev et al.Müller, E., Tolujew, J., & Kienzle, F. (2012). PushKanban – a kanban-based production controlconcept for job shops. Production Planning andControl: The management of operations(April), 113. doi: 10.1080/09537287.2012.701021Ohno, T., & Bodek, N. (1988). Toyota ProductionSystem: Beyond Large-Scale Production:Productivity Press.Pisuchpen, R. (2012). Integration of JIT flexiblemanufacturing, assembly and disassembly using asimulation approach. Assembly Automation, 32(1),51-61. doi: 10.1108/01445151211198719Robinson, S. (2004). Simulation: The Practice of ModelDevelopment and Use (Vol. 67): John Wiley& SonsLtd.Siemens. Plant Simulation. fromhttp://www.plm.automation.siemens.com/en us/products/tecnomatix/plant design/plant simulation.shtmlSugimori, Y., & Kusunoki, K. (1977). Toyotaproduction system and kanban systemmaterialization of just-in-time and respect-forhuman system. Journal of Production (April2013), 37-41.Welgama, P. S., Mills, R. G. J., & Osmond, G. (1995).Use of simulation in the design of a JIT system.International Journal of Operations & ProductionManagement, 15(9), 245-260.
Figure 2: Information and material flow in the KANBAN system-two Japanese actually be a - The basic information carrier within the KANBAN system is a rectangular card, enveloped in a plastic case, called a KANBAN card KANBAN card is always at tached to the container that contains the parts for which the card is intended.