Malzeme ihtiyaç planlama sistemi ve bir uygulama
Material requirements planning
- Tez No: 46518
- Danışmanlar: DOÇ.DR. ORHAN KURUÜZÜM
- Tez Türü: Yüksek Lisans
- Konular: Mühendislik Bilimleri, İşletme, Engineering Sciences, Business Administration
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1995
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 139
Özet
İşletmelerin piyasadaki rekabete karşı güçlerim ekonomik olarak koruyabilmeleri için bir üretim yönetim faaliyeti olan üretim planlaması ve kontrolüne son derece önem vermeleri gerekmektedir. Çünkü üretim planlaması hangi ürünün üretileceğini belirleyen, teçhizat ihtiyacım ortaya koyan, ürünleri talep edildikleri miktarlarda ve istenilen zamanlarda yapılmasını sağlayacak çizelgeleri temin eden bir ön üretim faaliyetidir. Üretim planlama ve kontrolünün hedefi kaynak kayıplarım en aza indirmek ve üretimde en yüksek verimliliği sağlamaktır. En yüksek verimlilik ise istenilen miktarda ürünü, istenilen zamanda ve kalitede en iyi ve en ucuz yöntemlerle üretmekle sağlanır. Talep tahmini üretim planlama ve kontrol fonksiyonlarının ilki olan ön planlama safhasında yapılmaktadır. Talep tahminleri programlarım ana çizelgelerin, satın alma siparişlerinin, üretim planının insan makina ve araç ihtiyacının teminine temel oluşturmaktadır. İşletmelerde politika ve hedefler stratejik planlar ile sağlanırken bunların somut kararlara indirgenmesi, daha kısa zaman dilimleri için hazırlanan taktik planlar ile sağlanır. Bu düzeydeki planlar genellikle fonksiyonel yapıdadır ve toplu üretim planlama (TÜP) bunlardan biridir. TÜP, işletmelerde orta vadeli planlama aracıdır. Toplu üretim planlan, taleplerin mamul gruplarına göre belirlenmesini sağlayan üretim stratejilerim yaratırlar. TÜP, işletmenin uygulayacağı üretim oranım belirleyen fonksiyon olarak tanımlanabilir. Orta dönem planlama hedeflerinin etkin biçimde gerçekleştirilmesi için, daha kısa dönemli modüler yapılı planlardan oluşan ana üretim programı kullanılır. Ana üretim programı, modüller arasındaki koordinasyonu sağlayacak şekilde üretim planlamasında anahtar rol oynar. Malzeme ihtiyaç. planlama, üretim planlama ve envanter kontrol faaliyetlerini gerçekleştiren bilgisayar destekli bir sistemdir. Malzeme ihtiyaç planlama programı, ana üretim programından hareketle envanter durumunu, temin sürelerini hesaba katarak planlanan amaçlar doğrultusunda malzeme ihtiyaçlarının bir programım yapmaktadır. -X11-.
Özet (Çeviri)
In todays competitive marketing conditions companies must follow a serious manufacturing policy to control production flow to minimize the production costs and to supply their customers orders on the due dates. By means of their high working rates and with relational data base structure, using computers in this field is more advantageous. To control production effectively and to produce economically the companies management must know approximately what output will be needed during a future time period. The company must produce only the number of items that can be sold by the sales department. It will do no good to produce more items in order to get a lower cost per unit if the sales department can not sell the additional units even a lower price. The volume of production should stem from a forecast of sales unless there is a shortage of raw materials or of production facilities and personnel. Such a forecast is always approximate. The importance of forecasting future sales cannot be underestimated. The failure to forecast future sales may mean the production of more goods than the market can absorb and result in an excess finished goods inventory for the company. Low consumer income or a better selling substitute product might prevent the goods being absorbed. An excess finished goods inventory may mean financial ruin for a company, but under production is also financially bad. If a company does not produce enough good, it does not make the maximum possible sales, with the result that the cost per unit is probably not at its lowest point Many business have suffered such financial loss because they have not analyzed their marked position and estimated future sales. Manufacturing has been described as the primary source of all wealth in the world. It has clearly been the corner stone of the great economic growth in western society. But it has become a very difficult process to control That's largely because of the way manufacturing operations have evolved over the years. Manufacturing systems and methods developed in recent years our being developed in the way to profit maximum advantage from computers, hi these study, the definition of MRP system, its purpose and application is described and its tried to describing the knowledge of manufacturing and also various systems related to manufacturing. In the second part, the planing phase of production system has been described. Production planning is the processes of the through the current mission of the organization and the current environmental conditions facing it, than setting forth a guide for future decision and result. Production planning is concerned with the determination of production, inventory and work force levels to meet fluctuating demand requirements. This process is based on three steps; L- ?XHl--Long tenn strategic planning, -Medium term tactic planning, -Short term planning. Strategic planning is buut on fundamental concepts, that current decisions are based on future conditions and results, that strategic planning is a process that it embodies a philosophy and that it provides a linkage or structure with in the organization. In the production or operations function strategic planning is the broad, overall planning the proceeds the more detailed operational planning. Executives who head the production and operations function are actively involved in strategic planning, developing plans mat are consistent with the firm's overall strategies as well as such functions as marketing, finance accounting and engineering. Once developed, production and operations strategic plans are the basis for operational planning of facilities and operational planning for the use of the faculties. In the third part, the tactical planning a control of manufacturing has been described. A tactical production plan is sometimes called an aggregate plan, resource requirement plan or a rough cut resource plan. The tactical plan is used to determine the impact of planned production on key resource considerations such as the work force levels, overtime requirements, machine capacity limitations. A tactical production plan also begins with a sales forecast The forecast may be a detailed as the master schedule, but most likely it is only as detailed as necessary to accomplish the purpose just stated. Normally the forecast detail for tactical planning is by product group, subdivided by each major finishing process. A tactical production plan developed from the forecast relates to manufacturing unit, not a business unit A tactical plan may bring together similar products that may be sold to different markets. Tactical production plans are mostly built around bottleneck operations and finishing or final assembly operations. In the manufacturing environment, inventory scheduling capacity and resources are just a few considerations that require aggregate planning. As manufacturing facilities grow, the problems of planning and control become extremely complex. The production control department must schedule to meet fluctuating demands for increasing varieties of products. Master schedules must be found within operating and customer-relations policies of the company. Clearly a methodology is needed to assist the production control department in establishing these master schedules. Such methods are usually referred to as aggregate planning techniques. The objective of aggregates planning is the productive utilization of both human and equipment resource. The word aggregate means mat the planning is conducted at a gross level to meet the total demand from all product that' share the same limited resources of a dedicated facility. In the production control flow of events, aggregate planning plays a critical role. oov-Ih the fourth part, these part describes the master production schedule (MPS). A master production schedule differs from a tactical production plan in that it is a detailed, item-by-item schedule of finishing products. It represents what a plant plans to produce, expressed in specific configurations of products or styles or colors or finishes. It specifies the dates on which the material is required and the exact quantity to be produced. The master schedule is usually subdivided in weeldy, rather than monthly, time increments. It is generally developed for each specific manufacturing organization where final determination of the finished product is established. A tactical production plan and a MPS complement each other. The tactical production plan is used the set the output level that must fit within the MPS. After the specific items to be produced are verified, the MPS is used to verify that the aggregate tactical production plan will cover the demand as it currently appears. In the fifth part, MRP system has been described. Material requirements planning (MRP) is a computational technique that converts the master schedule for end products into a detailed schedule for the raw materials and components used in the end products. The detailed schedule identifies the quantities of each raw material and component item. It also indicates when each item must be ordered and delivered so as to meet the master schedule for final products. MRP is often thought of as a method of inventory control. While it İs an effective tool for minimizing unnecessary inventory investment, MRP is also useful in production scheduling and purchasing of materials. The master schedule provides the overall production plan for the final products in terms of month-by month deliveries. Each of the products may contain hundreds of individual components. These components are produced from raw materials, some of which are common among the components. For example, several components may be made out of the same sheet steel The components are assembled into simple subassemblies, and these subassemblies are put together into more complex subassemblies, and so on, until the final products are assembled. Each step in the manufacturing and assembly sequence takes time. All of these factors must be incorporated into the MRP calculations. Although each calculation is uncomplicated, the magnitude of the data is so large that the application of MRP is virtually impossible unless carried out on a digital computer. Material requirements planning is based on several concepts that are implicit in the preceding description but not explicitly defined. These concepts are: 1 -Independent versus dependent demand. 2-Manufacturing lead times. 3-Common use items. -xv-The distinction between independent demand and dependent demand is important in MRP. Independent demand means that demand for a product is not directly related to demand for other items. End products and spare parts are examples of items whose demand is independent Independent demand patterns must usually be forecast Dependent demand means that demand for the item is related directly to the demand for some other product MRP is the appropriate technique for determining quantities of dependent demand items. These items constitute the inventory of manufacturing raw materials, work-in-process, component parts, and subassemblies. That is why MRP is such a powerful technique in the planning and control of manufacturing inventories. The lead time for a job is the time that must be allowed to complete the job from start to finish. There are two types of lead times in MRP: ordering lead times and manufacturing lead times. For the MRP program to function property it must operate on datacontained in several files. These files serve as inputs to the MRP processor. They are: 1. Master production schedule 2. Bui of materials file. 3. Inventory record file. The master production schedule is a listing of what end products are to be produced, how many of each product are to be produced and when they are to be ready for shipment The bul of materials file is used to compute the raw material and component requirements for end products listed in the master schedule. It provides information on the product structure by listing the component parts and subassemblies that make up each product The inventory record file is referred to as the item master file in a computerized inventory system. The material requirement planning processor operates on the data contained in master schedule, the bul of material file, and the inventory record file. The master schedule specifies a period by period list of final products required. The BOM defines what materials aid components are needed for each product The inventory record file contains information on the current and future inventory status of each component The MRP program computes how many of each component and raw material are needed by 'exploding' the product requirements into successively lower levels in the product structure. At the end of the firm part; some of lot sizing techniques has been described. In recent years, the traditional interest in the classic problem of the economic order quantity (EOQ) has shifted to lot sizing in environment of discrete period demands of MRP systems, which express demand for inventory items in descreate time series fashion, by computing time phased gross and net requirements. -XVI-.The most widely recognized approaches to lot sizing are as follows: 1. Fixed order quantity, 2. Economic order quantity (EOQ), 3. Lot for lot, 4. Fixed period requirements, 5. Period order quantity (POQ), 6. Least unit cost (LUC), 7. Least total cost (LTC), 8. Part period balancing (PPB), 9. Wagner-Wbitin Algorithm, 10. Gozinto Algorithm. The first two of the above are demand rate oriented; the others are called discrete lot sizing techniques, because they generate order quantities that equal the net requirements in an integral number of consecutive planning periods. MRP is simply a formalization of the informal system known to every plant It uses the computer in the following ways: 1. To run a master schedule against automated bills of material to determine which materials are needed to make the product and checks and inventory to see if these material is on hand. 2. If the material is not on hand or on order, it establishes the due date and releases a purchase requisition or shop work order. 3. If mere is an open order for the material, it win reevaluate the due date and tell the planner if the due date needs adjusting. These procedure is a formal system that predicts shortages just as and expediter might try to do, but it looks far enough ahead to allow something to be done to prevent the shortages. Material requirements planning systems are uniquely applicable to manufacturing. MRP is generally inappropriate for distribution or warehousing businesses mat deal with finished items. It is, however, a superior inventory management tool in manufacturing environments mat deal with assembled products. MRP's applicability is determined by the nature of demand of the inventory items being considered. The independent / dependent demand principle serves as a guideline for determining which inventory management technique - order point or requirements planning - should be used in a given situation. The principle states that inventories of independent demand should be replenished using order point, but inventories of dependent demand item should be calculated within the framework of a MRP system. Companies interested in utilizing MRP need: 1. A realistic master schedule, 2. Accurate bills of material, 3. Accurate inventory record files. -xvn- I
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