Simulation study of constant work-in-process oriented production control

V magistrskem delu se osredotočamo na problem, ki se pogosto pojavlja v svetu industrije. Ker je za konkurenčnost podjetij pomembna tudi kakovostna zasnova vodenja proizvodnje, se tudi v praksi zadnje čase poudarja pomembnost nekaterih znanih in manj znanih algoritmov, s katerimi lahko izboljšamo produktivnost proizvodnih linij. Pri klasični množični proizvodnji se temu posveča premalo pozornosti, posledično pa se pri proizvodnih podjetjih pogosto pojavljajo izdelki brez končnega kupca in se znotraj sistemov kopičijo prevelike zaloge, kar povečuje končne stroške izdelave in zmanjšuje dobiček podjetij. Teoretični del zajema osnovni zgodovinski pregled na področju vodenja proizvodnje, opis ključnih terminov, ki so se s časom razvili na tem področju, in opis razlik med različnimi načini vodenja proizvodnih procesov s poudarkom na zaenkrat v svetu manj znanem algoritmu ConWIP, s katerimi omejujemo količino sproščenih opravil v proces in posledično kopičenje nepotrebnih medprocesnih zalog. Ker je dinamika vsakega proizvodnega procesa unikatna, je težko načrtati algoritem, ki bi dobro deloval na več, sicer podobnih, a vendar s strani vodenja povsem različnih procesih. Zaradi potrebe po prilagodljivosti smo v nalogi poleg osnovnega mehanizma ConWIP predstavili tudi nekaj fleksibilnih izvedb. Ker je ocenjevanje ustreznosti posameznega algoritma na realnem procesu lahko časovno zamudno in finančno obremenjujoče za podjetja, se je na tem področju uveljavila diskretno dogodkovna simulacija, ki nam omogoča, da lahko delovanje pred vpeljavo v dejanski proizvodnji preizkusimo na modelih. Tako smo poleg teoretične obravnave v delo vključili simulacijsko izvedbo algoritma ConWIP v programskem okolju Simulink SimEvents, ki je del programskega orodja Matlab. Za izvedbo simulacijskih primerov, kjer smo prikazali in analizirali delovanje algoritma, smo izbrali dve različni proizvodni liniji, eno enostavno s štirimi zaporednimi delovnimi postajami ter eno fleksibilno in za modeliranje zahtevnejšo linijo. Pred izvedbo pa so predstavljene osnovne zahteve za delovanje mehanizma in preizkus mehanizma na enostavnem testnem primeru. Rezultati simulacij so potrdili naše hipoteze o smiselnosti uporabe takega algoritma in pokazali, da bi se posledično lahko zmanjšali stroški proizvodnega procesa, kjer medprocesne zaloge predhodno ne bi bile ustrezno nadzorovane.In this master\u27s thesis, we focus on a problem that is frequent in the industrial world. Since effective production management is very important to ensure business competitiveness, the importance of some known and lesser known algorithms used to improve productivity of production lines has recently been stressed in practice as well. In terms of classic mass production, this aspect is paid too little attention, which results in companies producing products with no final buyer and excessive stocks piling inside systems, which increases costs and reduces companies\u27 profit. The theoretical part provides a historical overview in the field of production management, describes key terms gradually developed in this field and presents key differences between different types of production process management, emphasising a currently less known algorithm, ConWIP, used to restrict the quantity of tasks released into production process and, consequently, excess work-in-process. Since the dynamics of each production process is unique, it is difficult to develop an algorithm that could be applied to multiple processes, which are similar to one another, yet in terms of management completely different. Due to the need for adaptability, in addition to the basic ConWIP mechanism, we also presented some flexible implementations. Companies may find suitability assessment of individual algorithms in a real process time- and money-consumingin response to this, a discrete event simulation has been developed in this field, allowing us to test the algorithm on models before its implementation in the real process. In addition to a theoretical background, this paper thus includes a simulation of the ConWIP algorithm on the production line model in the Simulink SimEvents software environment, which is part of the Matlab software tool. In order to build simulation model and analyse the algorithm, we selected two types of production lines: the first one simple with four successive workstations and second one more flexible and more complex for modelling. Before the final simulation version itself, basic requirements for mechanism operation and test on a simple test case are presented. Simulation results confirmed our hypotheses about the usefulness of such algorithm, and they showed that production costs could be reduced if the algorithm was used in a real process in which amount of work-in-process would not be controlled appropriately