Bilgisayar destekli üretim ortamının simulasyonu

Abstract

The mass production method is defmite as producing a defined quantity of goods in öne step, which is especially used in medium scale plants that has various kind of products. in this project, in the automation of mass production it is aİmed to establish a solution bridge between operators and production units when the analysis made by known methods are no more valid, also, the model of plant is established and the problem is tried to solve by applying simulation method. INTRODUCTION : Todays, production are getting more important due to difficulty of continuation of the firms in the competitive market conditions. The production technics can be named under the four main headlines : 1. Continious flow process, 2. Batch Production, 3. Mass production, 4. Jobshop production. The production quantity and variety of goods are two main factors in deciding the type of production method. Now, we try to examine these production methods briefly: in continious flow process, obviously, continious automation of the process is required. The petroleum rafmeries and chemical plants are two appropriate samples to this type of production method. Due to lack of uninterrupted control and prediction of problems and feedbacks should be applied in small periods, make the application of the automation necassary in the continious flow processes. The automobile production lines can be regarded as second type of production method. in that type, the production is continious and in high amounts, so automation is valid for ali system. The steps of production should be settled for each type of goods. Due to high amounts of production, the automation cost can be faced easily. Since high cost of human labour and lack of high quality, the robotics systems have been used in high capacity production plants for a long time, and, obviously this is ideal for continious flow process method. ix in mass production method, the amounts are in medium scale. Especially, printing houses and garment industry work in this manner. Although existing of too many kinds, it can be easily seen that, variation is around some main structures, and also the production is in öne step and in high quantities. The ship and plane building plants and heavy machinery workbench production are main examples of jobshop type production method. The production is various and, in common, the produced machine cannot be reproducable again in same dimensions. in this type of production engineering spends have an important portion in total cost. The custumer requirements are regarded as vital part of production. Although, using computer has an important wellfare in control of workbenchs such as milling machines ör lathes, in the design and project studies and also in management, looses its effectiveness in the total automation of production process. Usually, due to the high weight of product, it should be stationary and the workbenchs are settled around the product (ex.. construction of bridge). When the mass production method is examined detaily, such a condition can be faced:. For the integration of a model in a mass production method, the good should pass from each machine in a definite order and the time passed in each machine can be different for another type of product.. The capabilities of vvorkers in production has great effect on production period. For those reasons, the corner stones of mass production method; product, machines and workers should be examined, so we will mention this subject more detaily later on. The previously determined production steps are known during production period but, the time spent in each step depends on :. The capability of worker on that machine,. The probability of reliability of machine,. The probability of vvhether the worker is on machine ör not. ( due to health ör any other problem). So we are facing with a stochastic condition. Since the reasons mentioned above, it is not possible to determine the number of the machines during production period, when the production of n different model is required by using deterministle ways, but also this gives us a starting point. For that reason the necessity of solutions depend on stochastic and simulation is obvious. X BASIC METHOD USED İN SIMULATION : The choosen process method in this project is the mass production method. Some basic laws which are valid for this type of production method are mentioned below:. The proses is continious.. The number of variety of goods which are planned to produce is nn, but the variety of goods in the factory is n. The kinds of goods in the production field should be organized such that, the machines and operators can be sufficient for the production.. There may be more than öne machine to do same work. Although, there are m various kind of machine, also there may be different quantities for each type of machine. The quantity of machine is represented by q. « The quantity of machines is greater than the quantity of operators.. An operatör can use more than öne type of machine but, he can not show same skill on every machine.. Appropriate to the production flow, the quantity of machines may differ, but at the same time, due to the fixed number of operators the total number of machines will be constant, so, an operatör can use another machine only if he leave a machine. in the mass production method; whose basic laws are specified above, the production period last as defined below:. in a definite period of time, for example in a week, the goods which will be produced are settled to the entry queue orderly by regarding the production priorities.. When the production begin, the goods in the entry queue are sent to the production field in the order of its production priority. « The product will entry to the queue of a new production step after the previous step is finished.. At each production point, there is the probabilty of being three type of product:. reserve product,. the product working on,. completed product. xi . The product passed through all production points will entry to the exit queue, and from there it is sent to the store-house.. An other point important during the production period is the queues. As mentioned before, there are three type of queues in a production field.. Entry queue,. Interqueue,. Exit queue. The completeness of the organization of production field can be easily understood by the unaccurance of queues and inexistance of waiting products at production points. The existance of interqueues or the condition that a production point is waiting work are two main reasons to reorganize the production field. The existance of an interqueue may be due to the reasons occured next production point, which are axamined below:. The damage or spoilt of the machines,. A worker may get rid of work due to a reason,. The capability coefficient of workers may decrease due to a reason,. There may be a problem about the product working on. AIM OF THE PROJECT : The aim of this project is the simulation of a production process and displaying the drawn conditions by modelling the production machines and workers as in real world and also preparation of a condition inwhich the user can reorganize and apply the required differences during the process. To reach that aim, the aggrement of workers and machines on which stochastic structure is examined and under the light of these facts the process is modelled. After than the transient simulation of production machines is displayed to the user on the computer screen. To computerize all the explained things above, the programming language TC++ is used. In the second part of the project, the basic definitions used in modelling, approaches and main logic of simulation are given. In third part, the programming technic of simulation method whose main descriptions are previously described in second part, is given. Xll In the fourth part, the resource codes of written program are specified. In the fifth part of the project, the conclusion and recommandation of study are put in consideration. The confection factory examined in this project, in which ready made clothes are producing is a typical example of the mass production method. Since, to make the project easily understandable, a knitting factory is taken as a sample, and each product is regarded as a model. For that reason, to respond the mass production method, more than one factory was examined, interviews were made with autorized personel to determine the problems in this type of production method.