Tam zamanında üretim sistemi ve imalat kaynak planlaması (MRP II) sistemi ile ilişkileri
Just-in-time productıon system and its relatıons with MRP II (Material Resource Plannıng)
- Tez No: 39859
- Danışmanlar: DOÇ.DR. MEHMET TANYAŞ
- Tez Türü: Yüksek Lisans
- Konular: Endüstri ve Endüstri Mühendisliği, Industrial and Industrial Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1993
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 139
Özet
İnsanlık yüzyıllar boyunca gerek sosyal gerekse bilirnsel ilerlemesini sürdürürken pek çok problemle karşılaşmış ve bunları ortadan kaldırmak için çeşitti yöntemler ve sistemler geliştirmiştir. Zaman geçtikçe artan dünya nüfusuna bağlı olarak artan liretim ihtiyaçları sonucu, gelişen teknoloji ile kârlılık ve pazar ortaklığına dayalı endüstriyel toplumlar ortaya çıktığında pek çok konuda olduğu gibi üretim alanında da sistemler yaşam üzerinde baskın hale gelmiştir. Belirtilen nedenlerden ötürü ve özellikle de kıt kaynakların mümkün olabildiğince verimli kullanılması ihtiacı 19-40' lı yılarda Japonya1 da yepyeni ve farklı bir üretim sistemi geliştirilmesine neden olmuştur. ingilizce adıyla Justin-Time türkçe adı ile de Tam Zamanında üretim adı verilen bu sistem, uygulama koşulları kullanan firmaya uygun olduğunda firmaya büyük yararlar sağlamaktadır. TZÜ basit olarak doğru samanda ve uygun kalitede yapılan ve satın alınan doğru gerekli miktarları herhangi bir israfa yol açmaksızın sağlayan (temin eden bir sistemdir. Son yıllarda üretim planlama ve kontrolü için Batıda yaygın olarak kullanılan diğer bir sistem de MRP II, İngilizce adıyla Manufacturing Resource Planning, firmanın tüm fonksiyanlarını içeren ve bu fonksiyonlar arasında iletişim sağlayan“ Üretim Kaynakları Planlaması ”sistemidir. Bu çalışmada Gerekli birimlerin gerekliği yer ve samanda gereken miktarlarda üretilmesi amanı taşıyan ancak kullandıkları yöntemlerde farklılık gösteren bu sistemler öncelikle Tam Zamanında Üretim Sistemi olmak üzere ele alınmış "v'e tırmanın üre tim kaynaklarını planlarken kullandığı bilgileri olduğu gibi kabul eden ve onları iyileştirmek için herhangi bir faliyette bulunmayan MRP II sistemi ile Tam Zamanında üretim sisteminin bir karşılaştırılması yapılmıştır. Sonuç olarak bu iki sistemin birbirlerinin eksiklerini tamamlayacak şekilde bir araya getirilmesiyle oluşturulacak yeni bir Meles sistem ( Hybrid system 3 üzerinde durulmuştur. Uygulama aşamasında ise imalat firmaları için entegre bir kaynak yönetim ve kontrol sistemi olan ve öselhlde bütün MRP II uygulama olanaklarını da beraberinde getiren MTMS l] Manufacturing Total Management Solution } ve Executive Line paket programlan genel hatlarıyla incelenmiş ve modüler bir tarzda ele alınarak açıklanan bu programın özellikleri seçilen örnekler aracılığıyla ele alınmıştır. -xx-
Özet (Çeviri)
This work describes and e^lains two management systems which has been used m E ast and West. One of them is the production flow and inventory control system used in Japanese automobile rnanuf acturing plants, in the plants of parts arid compo - nerrt suppliers to the aiitomcbilemartafacturers. and also in other industries is usually called the“ Toyota Production System ”in other words“ JusHfrTime Production System ”. The other system is MRP II ( Manufacturing Resource Planning J inclu ding all functions of a firm and can communicate between these functions. The designation“ Toyota Production System ”is used because the system was developed by vice president of Toyota Motor Company. Mr Taüchi Ohno. Toyota implemented the Toyota production system under Mr. Ohno' s guidance and direction over a period ot 15 years. The Toyota production system pervades all aspects of the production and inven tory flow process. It covers such areas as process design, job design, and job standar disation, economic lot sises and accelerated setup times, autonomatiom. Karfoari. Jido ka, Andon, Yo-i-don, and just-in-time production,. Shortly. a& of these create Toyota production system. Autonornationis a Toyota coined word that refers to the automatic or manual stopping of a production operation if a defective or abnormal part is produced. Kari han refers to the use ot a card system to control, not only in-process inventory, but also production flow and inventory flow trom parts and component suppliers. Jidoka is the Japanese term for a production problem warning system that alerts everyone to the source of the problem through a battery of lights mounted high above the pro duction operation or assembly tine floor. The battery of lights is called Andon. When a problem occurs at a production operation, the lights will turn to yellow or red. Yel low indicates a problem or slight delay. A red light means an actual production or as sembly üne stoppage because of a more serious problem. Yo-i-don is the Japanese term used for co-ordinated production of parts or subassemblies that simultaneously are produced for assembly into a next stage subassembly. The Jidoka } Andon light method is used to identify problems in any of the co-ordinates of the co-ordinated pro duction operations. Probably the most critical and important aspect of the Toyota production system is the just-in-tirne production concept therefore most of this work allocated to Just-in- time production system Just-in Time { JIT )is a disciplined approach to improving overall productivity and eliminating waste. It provides for the ?cost-effective production -and delivery of only the necessary quantity of parts at the right quality, at the right time and place, while -x-?using a minimum amount of facilities, equipment, materials and“human resources. JIT is dependent on the balance between the supplier* s flexibility and the user' s flexibility. It is accomplished through the application of elements which require total employee in volvement and team work. A key philosophy of JIT is simplification. Just -incime production accomplishes several objectives or -goals, mot all unrelated in a production operation. First, it reduces in process inventory and inventory produ ced suppliers to a considerable and significant extent. In Japanese plants of automo bile manufacturers inventory measured in days of production ranges from three to to rn' days. S econd, the lead time required to produce a part or subassembly is ”reduced considerably. The benefit of this is considerable in case of necessary design changes or modifications because of design errors or weaknesses. It has been reported that m one of the Japanese automobile engine plants the engine hlock that is cast early in the morning appears in a finished and functioning automobile engine at night. Third. with just-in-time production there is no surplus parts production, and no lost parts, which even if they are found later may have to be scrapped. Fourth, just-ifi-tiffie pro duction requires that all parts are in-process and“visible ”at all time. Hence there is no need of parts or subassembly expediter s. Finally, the low inventory level signifi cantly lowers the cost of hoi - ding inventory, including the storage space required to store in-process inventory. Just-in- time production is accomplished by a“puling ”system instead of a“pu shing ”system which is used in traditional production systems. In the traditional pro duction system, including the previously cited MRP (mariufacturmg recrement sys tem \ system, the production schedule of the final product is“ exploded ”to determi ne the requirements of al subassemblies and component parts that make up the final product. Allowing for adequate production lead times, the production schedules for al subassemblies and component parts are developed. As the component parts are produced they“ push ”on or up to the next production stage end eventually are“ pu shed ”to the final product assembly stage. If every thing goes well, al component parts and subassemblies will be completed or delivered on time and final assembly can take place as scheduled. Since delays can occur at any one of the rjumerous produc tion stages, the production schedules are usually provided with buffer times or buffer inventories to ensure that delays of a limited 'number of parts out of thousands ot parts and subassemblies do not delay the final product assembly. The above“push ”system is not only the traditional way of producing products, it is also current method of production in al American manuf acturing plants. The meth od is, however, traditional for most Japanese firms who have adopted the just-in-time production process which is a“pufl ”process of production control. In the“push ”process described above, the inventory hwldup is considerable and whereas in Japa nese firms inventory is measured in days of inventory (three or four days in the auto motive firms J.inthe United States it is measured in weeks of inventory. In the“pul ”system of production control, also called just-in-time.production, the more advanced stage of production draws just the right amount of inventory from the preceding process in order to keep going. 1 ach preceding process has, of course, its respective preceding process, and the practice of drawing just the right amount of in ventory from each respective preceding process continues right down to the raw ma terial stage, or in case of purchased parts or subassemblies, down to the parts or sub - assembly delivery stage. -xx-Based on the above“pull ”system, all parts production and subassembly ope - rations are connected together in the tree ot chains and each final product order will generate a“pull ”which will be felt throughout the tree of chains of production opera tions. The connecting links of all production and subassembly operations makes it pos sible for an entire production and assembly plant to engage in jus-in-time production with out the need of the the costly and comprehensive bureaucratic procedures em bedded in a computer-based or manual production control process based on the“push ”system concept. used or is using the traditional“push ”system of production control The important rneans of accomplishing just^n^nme production is the Kantian system of inventory con trol. Any ever-increasing number of companies.are introducing JIT, with many more wishing to do so. The company wishing to introduce JIT have to know : >: What are the benefits of JIT ? x What are the techniques of JIT '? >: How to implement JIT“? Most of this work tries to answer this questions and then compare JIT system with MRP II system. Let' s summarise these questions: Benefits of JIT '. JIT has a lot of important benefits in the areas of scrap, quality, rework, and worker attitude and responsibility. We can summarise this benefits as.”-“' Work-in-progress reduction x”Increased flexibility x law materials /parts reduction *? Increased quality '“' Increased productivity x Reduced space requirements x Lower overheads Techniques of JIT ; There are a very large number of techniques and appro aches associated with JIT. These major techniques fal into three main areas and these are : Manufacturing Techniques : Cellular manuf acturing, set-up time reduction, pul scheduling ( Kanban ). group technology, smallest machine, fool- proofing (pokayoke) üne stopping (jidoka J. U-shaped Ines. housekeeping methods ( seiri. seiton ). In this work, pull scheduling { Kanban J that is most important mararfacturing tech nique will he explained in more details. It will be touched on the other techniques shor tly. -xix-Production.' Material Control : JiT- MRP(haektTushing, flat bills of material ). U PT ( schedule balance and smoothing, ”under capacity scheduling, visible control ) Inter- Company JIT : JIT purchasing ( single sourcing, supplier Quality certifica tion, point-of -use delivery, family of parts sourcing ) Organising for Change: Quality. Continuous improvement, enforced problem solvingimplementatiof,“ These are the techniques with which most companies will probably begin their ef fort. JIT focuses on flow through the operation and ceMar manufacturing is one of the core techniques that leads to flow. A key analytical technique leading to cellular ma nuf acturing is group technology. These are supported by set-up time reduction. a key technique that enables manufacture to be in very small batch sises. Small batch sises in turn make continuous flow easier to attain. Once these have been implemen ted. the next technique that can be used is pull scheduling. This is ”normally known Kanban. These core techniques are supported by a host of other non-core JIT techniques. such as the principles of“ Seiri ”(putting away everything that is not needed j.“ Set on ”( ar- ranging those things in the best possible way ).“ Fokaybke ”(foolproof devices to pre -vent mistakes and defects }. But in this work, only Kanban technique (because of welHonown and most important technique ) will be mentioned. Implementing JIT : The main objective of JIT is the elimination of waste. Imple mentation focuses making this happen. To implement JIT effectively three areas must be considered. The first is that of quality. Very high levels of quality are a neces sary condition for JIT. Any JIT effort must have an accompanying quality improve ment programme. One core JIT philosophy is that of continual improvement. There is no best, only better. This goes hand-in-hand with the technique of enforced problem solving. There is more than distance separating Japan and America. In the field of pro - duction planning and inventory management, the two countries are going in different directions. To the east, it is Kanban ( subsystem of JIT };tofhe west, it is Manufactur ing Resource Planning ( MRP II }. MRP His a planning method of all resources of a manufacturing urrn effectively. Ideally, it gives operational planning results as units, financial planning results as mone tary units and includes simulation modules can answer to the“ what- if ”questions. MRP II is a composition ot several functions that al of them are dependent to eachother. These are work planning, production planning, master production sche - dule. MRP. CRP ( capacity resource planning J. production support systems for capa city and material It is created a general database with output of these systems. And all informations of these systems are joined with work plan, execution of purchasing rapport, loading budget, stock plan and so on that can be explained as monetary unit. Presentation of these rapports as monetary unit facilitates understanding events rap idly and making a decision more accurate for top level management. MRP His called as a“firm execution system ”and sometimes as“a computer model of firm”. Another word. MRP His a standard logical formal system can simula -xxix-te to test every action's effects cm^he real manufacturing company. It is a way to ta ke more accurate decisions between a lot of alternatives for top level management The goals of MRP II and JIT are identical to aid manufacturing companies in improving customer service, inventory turnover, and productivity. Spectacular results can be cited by the companies employing each. However, the tools used by JIT' s Kan- ban are dramatically different from the tools used by MRP II. >: Kanban succeed only where the user produces highly repetitive products. MRP II. however works equally well for highly engineered one- of-a-kind environ - ments. make-to-stock products, and finished-to-order products. K MRP II has better tools than Kanban, but these tools are more costly. It is very import ant for a company to properly evaluate not only the costs, but what the pay- backs will be. unless the general manager and his staff can visualise a sisable return, they will not invest enough of their time and energy to ensure that the company will become a successful user. * With an MRP II system, computer reports advise purchasing people what i - terns should be bought. The reports also suggest what existing purchase orders sho uld be rescheduled to either arrive earlier or later, based on the changing needs of the company. The planned orders permit purchasing to provide visibility to vendors bey ond the. lead times. Under Kanban. the vendors do get advance notification to permit prior planning to occur. From the master schedule, the customer sends to each of his suppliers a rol ling, ninety days projection. The notices to the vendors are treaded as“ unofficial or ders ”. They are used to aid the vendor in material and capacity planning, but do not constitute a firm commitment on the customer“ s part After the above emanations, the companies in the automotive, machine tool, el - ectrical, computing machinery and other discrete and repetitive manufacturing indus tries started implementing the set of manufacturing philosophies and techniques popu larly known asiust-rn-trrne ( JIT J in their operations needed to have a hybrid system that connects JIT and MRP II systems. With the implementation of JIT. many of the production processes must be rati - onalized or simplified, resulting in operating environments containing both repetitive and discrete processes a hybrid environment. Since the efforts to improve qualify, re duee inventory and simplify processes are on-going, the hybrid environment is always changing. Simplifying processes in a discrete environment creates a higher degree of repe - titiveness in many production operations. For example, proper implementation of work cells canreduce material handling, improve flow and obtain a higher degree of frequency of a set of operations for a rela ted group of parts or assemblies. Yet. this can complicate the task of scheduling pro duction using manufacturing resource planning ( MRP II ). As the JIT concepts become the norm, the need for change becomes evident. The need to manage and JIT production techniques such as kanban result in a hybrid - X1V--system. Ân approach to handling the ”hybrid system entails using MRP II to plan pro - auction while employing JIT to execute and control production. ÂU of the mentioned subjects will be explained and discussed in four chapter. Res pectively, chapter one allocated to the raising of JIT and a general looking at this pro duction system, chapter two allocated to regunrements of JIT system and Kariban sys tern, chapter three allocated to purchasing, quality and quality control functions aid JIT and chapter four allocated to comparison MRP II and JIT. End chapter ( chap ter five Jis a practise giving general informations about MTMS (ma-nufacturing total management solution ) and Executive Line that's integrated resource management and control systems for -manufacturing conıpanies.orferirigfuîlmanufacturirıgresom'- ce planning capabilities ( MRP II capabilities |i. In addition to these, a comparison tab le is given in chapter five to explain the differences of some production management systems. -xv-
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