Malzeme İhtiyaç Planlaması Ve Üretim Kaynakları Planlaması

Abstract

Üretim ortamında temel sorun ihtiyaçların sonsuz, kaynaklarınsa kıt olmasıdır. Bu da kıt kaynakların en verimli şekilde kullanılmasını zorunlu kılmaktadır. Kıt kaynakların en verimli şekilde kullanılabilmesi için neyin, nerede, ne zaman ve ne şekilde kullanılacağı, çözülmesi gereken ilk sorun olmalıdır. Bu sorunun çözülebilmesi için etkin bir malzeme ve kapasite ihtiyaç planlaması sistemi gerekmektedir. Basit malzeme ihtiyaç planlama sistemleri zaman içerisinde bilgisayarların da devreye girmesi ile, malzeme ihtiyaç planlaması (MÎP) ve kapasite ihtiyaç planlaması (K±P) sistemine dönüşmüş ve bu sistemler işletmelerde etkin olarak kullanılmaya başlanmıştır. Son olarak da malzeme ihtiyaç planlaması sistemi bilgisayarla bütünleştirilerek ÜKP sistemi geliştirilmiştir. Çalışmanın birinci bölümü giriş bölümüdür. Bu bölümde genel olarak ihtiyaç planlama sistemi anlatılmaktadır. ikinci bölümde Malzeme İhtiyaç Planlaması (MİP) sistemi anlatılmaktadır. M±P sisteminin kullandığı önkoşullar ve varsayımlar, sistemin girdileri, sistemin çalışması ve çıktıları bu bölümde ele alınmıştır. Bu bölümde son olarak sistemin değerlendirmesi yapılmıştır. üçüncü bölümde üretim Kaynakları Planlaması (ÜKP) sistemi anlatılmaktadır. ÜKP paketlerinin yapısı ve ÜKP sisteminin uygulama aşamaları bu bölümde anlatılmaktadır. Dördüncü bölümde ise halen MÎP sisteminden ÜKP sistemine geçiş aşamasında olan Bekoteknik Sanayii A.Ş.'de eski ve yeni sistemler karşılaştırılmakta ve yeni sistem anlatılmaktadır.

In today's competitive marketing conditions, companies must care about production planning and inventory control more than ever before to minimize the production costs and to supply customers' orders on the due dates. Computers proved to be very appropriate for Keeping records and files about inventory in most of the manufacturing corporations where thousands of different units are involved. Material Requirements Planning (MRP) is the most widely used design philosophy to deal with multistage production planning. MRP is essentially an information system and a simulation tool that generates proposals for production schedules which managers can evaluate in terms of their feasibility and cost effectiveness. An MRP system is a collection of logical procedures for managing, at the most detailed level, inventories of component assemblies, subassemblies, parts, and raw materials in manufacturing environment. It is a modern and, by necessity improved version of an older technique utilized for quite a while in scheduling multistage production operations, called "parts explosion", used in determining the amounts of components required in the manufacturing of 6ome end item. A key element to the determination of component requirements is the bill of material, which is an engineering document and can be represented as a symbolic exploded view of the end item stucture. A parts explosion implies computing the necessary amounts of every component material, part, subassembly, and so on required for the manufacturing of a given number of end item units. For this we have to know the "quantity per" factors, that is, amounts required of each component item in order to obtain one parent item. Then conceptually, it is quite simple ; multiply the desired quantity of a parent item by the "quantity per" factor to obtain the needed number of component item units, called "gross requirements". Repeat while going from top to the bottom of the bill of material. In the context of multistage production, distinguishion between independent demand and dependent - vii - demand should be made. The independent demand originates in market demand for an item. The demand by a parent item for its components is dependent demand. If an item is needed both as a component and as a spare part, this item is said to exprience both dependent and independent demand. An MRP system is designed to deal with dependent demand items. In the case of component items also having independent demand, forecast quantity is added to the gross requirement in the same period. As far as end-items are concerned, they are forecast and their production is planned outside MRP. This action results in what is called a "master production schedule". MRP accepts the master schedule as an input, assumes that it is feasible from the viewpoint of the resource requirements, and plans orders of component items accordingly. If planned load exceeds available capacity in some work centers, the problem is referred for solution to someone else. The system signals it but can not deal with this problem. Net Requirements are determined by netting the grosss requirements against any amount on hand or already on order. Lot sizing in the MRP context requires the construction of a dynamic multistage inventory model as each stage expriences a deterministic time varying demand Effective use of dependent inventory models requires that the operations manager know the: 1) Master production schedule (what is to be made and when) 2) Specifications or bill of material (how to make the product) 3) Inventory availability (what is in stock) 4) Purchase orders outstanding (what is on order) 5) Lead times ( how long it takes to get various components) The master production schedule tells what is required to satisfy demand and meet the production plan. - viii - This schedule establishes what items to make and when. Additionally, managers must adhere to the plan for a reasonable length of time. Many organizations, establish a master production schedule and then fix the near-term portion of the plan. The fixed portion of the schedule is then referred to as "fixed", "firmed" or "frozen" schedule. Only changes beyond the fixed schedule are permitted. The schedule then becomes a rolling production schedule. The master schedule can be expressed in terms of 1) an end item in a continuous (make-to-stock) company 2) a customer order in a job shop (make-to-order) company 3) modules in a repetitive (assemble-to-stock) company A bill of material provides the product structure. Bills of material are also useful for costing, and they can serve as a list of items to be issued to production or assembly personel. When bills of material are used in this way they are called "pick lists". Knowledge of outstanding orders should exist as a by-product of well-maanaged purchasing and inventory control departments. When purchase orders are executed, records of those orders and their scheduled delivery date must be available to production personnel. Only with good purchasing data can managers prepare good production plans and effectively execute an MRP system. Management must determine when products are needed. Only then can it be determined when to purchase, produce or assemble. This means, operations personnel determine wait, move, queue, set-up and run times for each component. When grouped together, these times are called lead times. While dependent demand makes inventory scheduling and planning more complex, it also makes it more beneficial. Some of the benefits of MRP are ı 1) Increased customer service and satisfaction 2) Improved utilization of facilities and labor 3) Better Inventory planning and scheduling - ix - 4) Faster response to market changes and shifts 5) Reduced inventory levels without reduced customer service. Although most MRP systems are computerized, the analysis is stright forward and similar from one computerized system to the next. A master production schedule, a bill of material, inventory and purchase records, and lead times for each item are ingredients of a material requirements planning system. Material requirements planning II (MRP II) has substantial applications beyond scheduling and inventory management. It is an extremely powerful technique. Once a firm has MRP Ilin place, inventory data can be augmented by labor hours, my material cost (rather than material quantity), by capital cost or by virtually any resource variable. When MRP is used in this way, it is usually referred to as manufacturing resource planning. Furthermore, most MRP II computer programs are tied into other component programs that provide data to MRP system or receive data from MRP system. Order entry, invoicing, billing, purchasing, production scheduling, capacity planning and warehouse management are a few examples. Manufacturing Resource Planning (MRP II) had evolved out of Material Requirements Planning (MRP) into a company game plan. And the successful users demonstrated that these tools could be used to raise the level of professionalism in running manufacturing businesses. It was the users who took the tools they had and extended them. Manufacturing Resource Planning (MRP II) is a game plan for planning and monitoring all of the resources of a manufacturing company ; manufacturing, marketing, finance and engineering. MRP II is literally a simulation of a manufacturing business. It can be used to schedule the factory, schedule vendors, plan manpower far better, plan capacity requirements for new equipment more accurately further into the future and with more capability of testing various plans. Structures of MRP II programs and application steps of a MRP II project is disccussed more detailed in Chapter 3. - x - Some of the results of implementing MRP II in an organization can be given as followsi 1) Increased customer service and satisfaction 2) Improved utilization of facilities and labor 3) Better inventory planning and scheduling 4) Faster response to market changes and shifts 5) Reduced inventory levels without reduced customer service. 6) Reduced production and purchasing costs 7) Improved adaptibility to regenerated plans 8) Decrease in over works and shifts In Chapter 4 of this study, an electronis company has been introduced in terms of production steps and product structures. Later in this chapter, the MRP system which has been used in this company till now and the new MRP II system which the company is at the stage of implementing is compared. The system areas manufacturing data, resource planning, inventory control, work-in-progress, sales control, purchase control, cost control, financial management, application utilities and foundation utilities in addition to the orderin policies of the new system has been explained.