Atelye tipi üretimde gazinto yöntemi ile malzeme ihtiyaç planlaması ve bir uygulama
In workshop type production system material requiremets planning by use of the method of gozinto and one application
- Tez No: 14388
- Danışmanlar: PROF.DR. AYHAN TORAMAN
- Tez Türü: Yüksek Lisans
- Konular: İşletme, Business Administration
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1991
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 91
Özet
ÖZET Bu çalışmada tipik bir Atelye tipi üretim sisteminde Ana üretim Planlama ve Kontrolü aşamasının ilk basamağı olan Malzeme ihtiyaç Planlama konusu Gozinto Yöntemi ve bilgisayar desteği ile incelenmiştir. Gozinto yöntemi Vazsonyi (1958) tarfmdan büyük sayıda ürün ve parçanın sözkonusu olduğu durumlarda planlamanın yapılabilmesi için matris cebrine dayalı sistematik bir yöntem geliştirilmiştir. Çalışmanın birinci bölümünde üretim Planlaması kavramına bir giriş olmak üzere Üretim Sistemleri üzerinde durulmuş, uygulamanın yapıldığı Atelye tipi üretim ile klasik üretim tipleri özet olarak tanıtılmıştır. ikinci bölümünde Atelye tipi Üretimde üretim Planlama ve Kontrol faaliyetleri detaylıca incelendi. Üçüncü bölümde Malzeme Planlama kısmı görevleri ve yapısı açısından ele alındı. Dördüncü bölümde ise Malzeme ihtiyaç Planlama (M.i.P) sisteminin teorisi ve uygulaması örnekler verilerek açıklanmıştır. Beşinci bölümde ise Malzeme ihtiyaç Planlama (Gozinto) kararları ele alınmış olup aynı zamanda Kapasite ihtiyaç Planlaması da ele alınarak M.i.P. sistemi ile olan ilgisi incelenmiştir. Altıncı bölümde Atelye tipi üretim yapan bir işletmede (ADAPAZARI T. C.Z. DONATIM KÜRÜMÜ 'nda) bir mamul örnek alınarak Bilgisayar yardımı ile uygulama yapılmıştır. Bu uygulamada mamulün tanıtımı, veriler ve bu verilere göre Bilgisayardan elde edilen çıktılar yer almaktadır. Sonuç bölümünde ise çalışmada elde edilen sonuçların yorumu ve konu ile ilgili genel bir değerlendirme yer alıyor. VII
Özet (Çeviri)
SUMMARY IN WORKSHOP TYPE PRODUCTION SYSTEM MATERIAL REQUIREMETS PLANNING Bf; USE OF THE METHOD OF GOZINTO AND ONE APPLICATION The method of material requirements planning (MRP) was developed specifially for the purpose of dealing with the complexity of these timing and inventory relationships in the discrete parts manufacturing environment. Fundamental to the MRP approach is the distinction that is made between independent and dependent demand as it affects inventory and production decisions. In practice it is rare to find situations in which demand is constant, although this may be a good approximation where the variance to mean ratio of demand is quite small. More often than not, demand for an item comes in lumps; tahat is, some units may be demanded during one period of time and then there will be ne demand for awhile. This is especially true within a discrete parts production facility. Demand for a particular blank of raw material stock from which a part is to be machined occurs only when that part goes into production. In a discrete parts production facility, in which there are typically 20.000 to 100.000 component parts, the demand for that particular blank, will be infrequent. Hence inventorying that blank based on a continuous demand model is inappropriate. A statistical inventory model may be appropriate to describe final demand for the end products of the firm. End product demand is said to be independent demand, since it originates from independent sources outside the production system. However, the demand for subassemblies, component parts, and raw material stock is derived from the planned production levels of the end products. Once production planning determines the weekly master production schedule for end products, the requirements for subassemblies, components and raw stock items related to those and products can be simply computed. For this reason, it is said that demand for these items are dependent on the planned production of final products. VIIIThe manufacturing routing sheets and product bills of materials describe the departmental routing and production times to manufacture the subassemblies and components. Using these data bases in conjunction with a schedule of end product requirements, it is possible to compute the timing of production for each component to meet the given end product schedule. This, in effect is what an MRP system does. In other words, given a master schedule of end (or final) product, MRP computes the timing of all the subassembly, component, and raw material production and purchasing activities required over the specified production horizon to meet the master schedule af the end product. Moreover, it does so in such a way as to attempt to minimize workin-process inventory. The methods of MRP are not new. However, until recently, it has been economicall impractical to employ these methods in any nontrlvial production situation. The dramatic reduction in computer cost oyer the last 20 years has changed that circumstance. As ve shall see, operating an MRP system requires massive data storage, retrieval and computational capabilities which can only be accommodated by computers. Once a master schedule of end product production is determined, production planning roust address the problem of producing subassemblies and components. Components are produced or purchased from which subassemblies and final assemblies are eventually made. Therefore, when a master schedule is proposed, the first problem is to convert it efficiently into the requirements for purchased and manufactured parts. This is referred to as performing a parts explosion. To present a formal description of the problem, we classify items to be produced into three categories: end items, subassemblies, and parts. A number of tabular and graphical procadures can assist us in developing an operations plan. Since some of these can be used as decision-making processes, they may be called tarnsfer functions. Their main use, however, is in conjunction with other operations planning taransfer functions. We discuss four tabular and graphical aids: bills of material, operations IXsheets, production flow charts, and requirement time profiles. The GOZiNTO procedure; We have seen previously that demand for finished goods is generated in two basic ways, sales forecast (when we produce for stock) and customer orders ( when we produce to customer order ). Regardless of how the demand for finished goods is generated, it in turn generates a requirement for subassemblies. The demand for subassemblies generates a requirement for fabricated parts and purchased part. The demand for fabricated part generates a demand for raw materials. We can see how this process works by reviewing the example involving the two bookcasas. In the example, we determined the number of square feet of sheet metal required to produce 10 units of each of the two types of bookcases. We could determine other parts and material requirements in the same manner for thee small problem, but this procedure would be too clumsy for larger problems involving more products and more parts. Vassonyi (1958) developed a systematic procedure based upon matrix algebra that provides a good framework for performing the planning function when large numbers of products and parts are involved. Large applications are normally performed on a computer. The solution cold be obtained using a linear programming software package or by other matrix inversion schemes, but the algorithm presented is much faster. In all computer applications of the Gozinto procedure, efficient schemes for packing matrices must be employed because of the large number of empty elements in the matrices. Gozinto Decisions; The procedure for determining parts requirements outlined in the previous section is most useful for processing customer orders for a single time period. When we want to determine requirements for forecasted demand over several time periods, an extended procedure is needed. Such a procedure, developed in this section, will also generate a great deal more information needed in making several other planning decisions.The decisions to be rendered are: 1. Time-phased parts requirements (gross). 2. Time-phased parts requirements (netted against stock on hand and outstanding production and purchase orders). 3. From decision 2, we can obtain these decisions * Whether to order raw materials; how much to order. * Whether the requirements can be met with present capacity, considering machine time and man-hours availeble. Possibilety of extra shifts and overtime is considered. We used the Gosinto procedure to determine the time-phased requirements for finished goods, subassemblies, fabricated parts, and purchased parts. We can apply the Goainto procedure to the forecasted demand pattern of each of our products for an entire planning period, thereby obtaining the number of each stock number needed for each month's expected demand. We can now convert unit requirements to machine hours, or simply to processing time in each department, and then summarise each department's time requirements for each operating period (usually 1 month ) in the planning period (usually 1 year). In this stuty, Material Requirements Planning, which in the first step of the Main Production Planning and Control in a typical workshop type production system, has been studied by the method of Gozinto and using the computer. In the first Chapter at the study, the production systems have been studied in order to introduce the production planning. Concept; and the workshop type production and classical production types have been analized in summing up. In the second Chapter, production planning and control activities in the workshop production type have been studied in detail. XIIn the third Chapter, the structure and functions of the Department of Material Planning have been analyised In the forth Chapter, the theory and practice of Material Requirements Planning (MFP) have been explained with the examples. In the fifty Chapter, Material Requirements Planning (or Gozinto) decisions have been analyised and also the capasity requirements planning has been exemined in the relation with the material requirements planning. In the sixth Chapter, a sample product has been taken and with the using a computer, this product has been studied in a firm that uses workshop production type in Adapazarı (Adapasarı T.Z.D.K). In this exercise, the defination of the product, data and the outputs based on the data have taken placa. In the conclusion Chapter; the interperetation of the results which were obtained from the study and a general evaluation related to the subjekt have taken place. XII
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