Tam zamanında üretim sistemi ve bir yan sanayi işletmesinde değerlendirilmesi
Just in time production system and evaluation of fit
- Tez No: 66721
- Danışmanlar: PROF. DR. SITKI GÖZLÜ
- Tez Türü: Yüksek Lisans
- Konular: Mühendislik Bilimleri, İşletme, Engineering Sciences, Business Administration
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 1997
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: İşletme Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 114
Özet
ÖZET İlk kez otomotiv sektöründe faaliyet gösteren Toyota motor firmasında doğan, çeken sistemler olarak da adlandırılan Tam Zamanında Üretim Sistemlerinde sıfır hata, sıfır stok ve sıfır hazırlık zamanlan ile üretimin sağlanması hedefine, verimli malzeme hareketi, yüksek motivasyon ve sabit işlem zamanlan ile desteklenmiş stok yönetimi uygulanarak ulaşılmaktadır. Minimum kayıplar ile yüksek kalitede ürün üretilmesi neticesinde maliyet azalmasıyla sonuçlanan, organizasyonun tüm seviyelerindeki işe yaramayan uygulamaların sistematik olarak elenmesi ve sistem, teknoloji ve insan yönetiminde etkinlik anlayışı üzerine kurulan TZÜ felsefesi dağıtım ve lojistik fonksiyonlarının yanında satınalma ve malzeme yönetimini içeren belirli uygulamaları da içermektedir. Maliyet ve fiyatlar üzerinde direkt etkili bir sosyo ekonomik güç olan, stok kontrol, planlama, sipariş etme ve malzeme çizelgelemenin imalat sisteminde kullanılması anlamına gelen satmalına, faaliyetler sırasında kalite gereksinimlerini karşılayacak doğru malzemenin, doğru kaynak ve yerde, doğru zaman ve miktarda, doğru fiyattan, doğru hizmet ile elde edilebilmesine dayanmaktadır. TZÜ uygulamasının en önemli unsuru olan TZÜ satınalma, küçük miktarlarla sık teslimat, çok az sayıda tedarikçi ile yalan ilişki içerisinde çalışma ve malzemenin istenilen zamanda kullanımı için temin edilmesi esaslarına dayanmakta, stok-malzeme kontrol ve emniyet stoklan üzerinde etkili olup depolama için ayrılacak yer miktan ile hurda, ıskarta oranlarının azaltılmasını sağlamaktadır. TZÜ sisteminde amaç alıcıya gereksinim duyduğu zamanda, gereksinim duyduğu miktarda, yüksek kaliteli malzemenin, küçük partiler ve sık teslimat ile sağlanmasıdır. Tedarikçi firma günlük hatta saatlik sevkıyat yapabilecek esnekliğe sahip olmalıdır. Küçük kafilelerle çalışma prosesler arası sıkı bir stok kontrolünün uygulanmasını da beraberinde getirerek sistem genelinde hedeflenen sıfır stok kavramı gerçekleştirebilecek, gelen parçanın kontrolünü kolaylaştırarak hataların çabuk bulunmasını ve düzeltilmesini sağlayacaktır. Bu özellikler aynı zamanda tedarikçilerin sevkiyat performansının değerlendirilmesinde en önemli kriter olarak dikkate alınmaktadır. Bu çalışmada TZÜ felsefesi ve bu felsefe altında yan sanayiden ana sanayiye hangi kriterler eşliğinde sevkiyatlann yapıldığı irdelenmiştir. Çalışma müşterilerin sınıflandırılmasına ve mevcut üretim performansı sorgulanmadan, bu sınıflandırma baz alınarak makina, ürün özellikleri ve acil sipariş miktarlarına göre, kapasite planlaması faaliyetlerine dayanmaktadır. Kapasite üzerinde sipariş girilmesinin, öngörülmeyen makina duruşlarının ve üretim planlarının yapımı ve takibi sırasındaki hataların önlenmesi, makina kapasiteleri hakkında yeterli bilgi ve acil siparişlerin müşteri sınıflandırması çalışması dikkate alınarak kabulü ilkeleri ile firmanın Tam Zamanında Sevkiyat oranı % 62.5lardan 97 yılının ilk dört ayında %92.51ara ulaşmıştır. Ük iki bölümde sistem, sistemin işleyişi, olması gerekenler ve kavramlar verilmiş, son bölümde yer alan değerlendirmede de TZÜ sistemine geçiş dönemini yaşayan firmaların tedarikçisi bir firmada iyileştirme projesi olarak seçilen Tam Zamanında Teslimat sorununun hangi metodlarla ve nasıl bir uygulama ile çözümlendiği anlatılmıştır. VI
Özet (Çeviri)
SUMMARY JUST IN TIME PRODUCTION SYSTEM AND EVALUATION OF JIT AT A SUPPLIER FTRM The concept of Just In Time Production System (JIT) that can be expressed as an approach, a methodology, a way of thinking or a strategy, has emerged from the idea of American supermarket and first used in Toyota Motor Co. which operates in automotive sector. JIT means an operation of material aiming that the right parts are produced at desired quantity, time, place and quality in a flow of business and it can be accepted as an industrial culture change and a result of total change in management thought. The real aim of JIT is increasing the productivity of the firm by the way of decreasing costs in the production process. JIT is not only a Japanese inventory management system that arises the interest and attention of personnel to the concept of quality providing a close relationship with suppliers, but also an international concept and approach that is known as perfection of production and application of operation management aiming at eliminating waste and holding no inventory. Also increasing quality and productivity at the same time is an important aim of JIT, too. The most important specifications of JIT are small lot sizes depending on monthly production plans, short set up times which is the core part of process design and low order costs. Implementation of JIT philosophy, resulting with a reduction in costs because of high quality production with minimum waste, includes the techniques of purchasing and material management with certain supplier certificates, MRP, MRP U, contracts, electronic data interchange, quality implementations of Deming, value analysis and job simplification as well as distribution and logistics functions. The elements of JIT are as follows: 1. Waste 2. Total Quality Control 3. Participation of Employees 4. Pull systems 5. Group Technology 6. Reduction of Set up Time Over production, waiting time, transportation, inventory and defective parts are main types of waste and under JIT it can be defined as increase of costs without adding any value to production process. The ultimate aim is the elimination of inventory which is the source of waste and all the other problems in the plant. JIT is based on production without holding inventory, the systematically elimination of all unuseful implementations at every level of organization and the effective management of the system, the technology and the people. In order to reduce the level of finished goods vuand work in process inventories that is one of the main objectives of JIT, the lot size and related with that set up time should be decreased. Shorter set up time provides smaller lot sizes that enable firms to adapt themselves to market conditions and also increases the effective usable time of machinery. In JIT which had been famous with Japanese and then took an important role in American industry, three types of inventory is controlled in order to provide lower unit and operation costs, optimum customer service, effective use of capital invested and to identify quality problems. By that way the tendency to hold inventory between production processes is prevented. The philosophy of JIT is based upon the idea of eliminating or reducing the inventories in the whole system. Japanese, being conscious of using the physical sources in the most productive way, liken the inventories to a wide and deep lake and the problems like wrong estimates, bottle-necks, unreliable suppliers, quality and industrial relations to rocks in that lake. JIT also reduces the purchasing costs as it prevents safety stocks. It is observed that the interdependency of processes increase after the inventory levels are reduced. Increasing interdependency causes effective and multifunctional communication, coordination and cooperation mechanisms and that part of JIT affects the organizational structure. Because of that the materials should be converted into products and sold on time. As the system does not allow to hold inventory in order to be used in place of unaccepted parts, high quality and standard materials are required. Distribution and quality problems, fluctuations in the production, inefficient purchasing policies and changes in macroeconomic conditions cause material inventory; Machinery breakdowns, defective production, long set up time, different worker productivity, absenteeism, insufficient maintenance and production planning, fluctuations in production cause work in process inventory; Demand fluctuations, defective products, production fluctuations and changes in macroeconomics conditions cause finished goods inventory. When the total flow of operations in production industry is taken into account as a scheme, reducing inventory will provide a rational benefit first from the buyer to the supplier and then from the supplier to its suppliers. In JIT production environment suppliers are required to make frequent deliveries in small lot sizes. This attitude minimizes the inventory holding costs of the buyer. In other words in JIT system the buyer has no financial burden for the material it purchases. In the case that the materials are kept in the plant of the supplier, the physically closer suppliers are preferred. Today not only the product, but also the quality is produced and sold. JIT and the quality are the supplementary concepts. Quality is a more important objective than the output in JIT production system. The success of JIT is dependent upon the supply of high quality material. In other words quality makes JIT possible. So what is quality? Total quality control that has an objective of customers' satisfaction of the quality of the product and no defects within the system, means the activities of development, design, production and after sale services that satisfy the demands of customers with the minimum cost and continuously improving for perfection. According to JIT philosophy this objective can be reached by reporting all the VUlmaterials processed in the production and all the problems related with production, by controlling the defects emerging because of machinery and equipment and by delegating the responsibility to the workers participating in the production. In other words production process is responsible for quality control. By that way defective parts and problems in the production line are determined by stopping the line and solved immediately. The workers are responsible of stopping the line and solving the problem when an error or quality problem occurs. Since the workers take place of the quality control personnel a closer control of processes and outputs becomes possible and as a result the level of quality increases. JIT is an implementation of management in order to increase quality and productivity and can be successful only by the participation of every department in the firm. Organizations should be flexible against unexpected problems that can occur during process flow. In the operational strategy and human resources policy of JIT, continuous improvement of all employees for better customer service, more product specifications, higher quality and lower costs take the place of the scientific methods in which experts determine everything. In JIT systems that are named as pull systems, the objective of no defect, no inventory and zero set up time can be reached by applying productive material flow, high motivation and inventory management supported by fixed operation times. In these systems as the later process pulls parts from the previous process in determined quantity and time every process produces on time to satisfy the demands of the later processes. By that way work in process inventory is eliminated and production scheduling and inventory control is performed by kanbans. Kanban which is a Japanese term meaning card, is an information system that controls the production quantity at every process and informs every process about production quantity and delivery time. Kanban does not only link the production phases by moving from the end to the start together with physical units but also provides the reflection of sudden changes in market conditions to the production system. This information system includes supply, transfer and production information and realizes the information flow both horizontally and vertically. Kanban can operate only under JIT conditions and helps set up time, lot size, work force, level of inventory and number of warehouses to be reduced whereas JIT can be successful without kanban. JIT purchasing is a socioeconomic power directly affecting the costs and the prices and means the use of inventory control, planning, ordering and material scheduling in production system. JIT purchasing is effective on inventories, material control and safety stocks and provides smaller place for inventory and less waste. The system is based upon frequent delivery in small lot sizes, a small number of suppliers that are in close relations and supply of material on time. JIT purchasing system was first used by Japanese and it is a part of JIT system meaning the delivery of 100% acceptable material on time. The most important element of JIT implementation is JIT purchasing which is directly effective on product quality and productivity. Today most of the firms begin to use JIT purchasing instead of traditional purchasing. During purchasing activities the right materials that will satisfy the quality needs should be supplied from the right source at the right time and place with the right quantity, right price and right service. This can be named as seven rights. Purchasing procedure of JIT includes the nine steps below: 1. Continuous service and material flow at right quantity and quality should be maintained from the suppliers, IX2. Inventory costs should be kept at minimum level, 3. Required quality standards should be continuously provided, 4. Efficient suppliers should be found and developed, 5. Purchased material should be standardized, 6. Required services and materials should be purchased at minimum price, 7. Purchasing should increase the competitiveness of the organization, 8. Close and productive relations with other departments of the organization should be established, 9. Purchasing objectives should be reached with possible minimum administrative costs. Purchasing is an important area of operational decision making. According to that, one of the important purchasing decisions is finding the efficient supplier group and continue to work with them. In other words the most important responsibility of the purchasing department is selection of the right source. The selection of supplier is a teamwork and generally in these teams people from finance, production, product development, quality, engineering and purchasing departments participate. Suppliers that are used passively in most cases are potential source of development for purchasing agents. It is observed that strategic management decisions affect the importance given to the different criteria during the selection of the supplier. As a result strategic decision making analysis in supplier selection constitutes an important area for future/ studies. Decisions like period of contracts, number of suppliers and place of suppliers should be analyzed by their strategic effects. The participation of suppliers that are few in number and providing high quality material to the buyer in required quantity and on time is essential for the successful implementation of JIT. For quality and delivery to be at the required levels, buyers and suppliers should work very closely and share all the information as soon as possible. In the long term working with physically closer suppliers can solve most of the existing and potential problems. Purchasing function which was an operational function in the firm once upon a time, now has the function of strategic orientation. When the multi-purpose nature of of supplier selection decisions and their financial importance in a highly competitive environment are taken into account, it is recognized that multi-purpose programming techniques can be useful. The process of supplier selection has experienced an important transformation in the last 20 years because of increasing importance of quality, development of computer communication and technological efficiency. The selection of suppliers and providing the required material, service and equipment are the most important purchasing functions. In today's competitive environment it is impossible to produce high quality but low cost products without efficient suppliers. So the selection and the management of the right supplier is the most important part of the JIT philosophy. The first step is the selection of the right supplier, but it is not the supplier which offers the lowest price. The supplier that provides on time delivery, the best quality and the lowest cost in total should be selected. By working with limited number of suppliers long term relationships can be established and required quality can be performed. The criteria for the selection of suppliers in JIT are as follows: 1. Quality, 2. Delivery,3. Net Price, 4. Geographical Place, 5. Production operations and efficiency (capacity), 6. Technological efficiency, technical skills and innovativeness, 7. Behavior, 8. The management and the organization, 9. Packaging, 10. Operational control, 11. Maintenance Service. In JIT production system, production and purchasing are based on frequent delivery in small lot sizes. The supplier should have the flexibility to make daily, even hourly deliveries. Working with small lot sizes will lead to the objective of no inventory by implementation of a tight inventory control between processes and also it will provide quick discovery of defects. In JIT system, in order to decrease lot sizes, set up time and set up costs should be decreased first. Price, quality, timing, flexibility and innovation that are reflecting the performance of the firms in highly competitive environment are determined partially by suppliers. This indicates that the competition should be traced at the level of industry and the manufacturing firms should undertake the responsibility of developing industry within a competitive supplier network. Delivery on time in required quantities requires a close relationship between the customer and supplier. In the global network of industry the firms help JIT developing by reducing production costs, improving quality and making the product cycles shorter. Restructuring activities in 1980's has changed the structure of the industry and the competitive environment. As the firms aim at having closer relationships with suppliers by reducing the number of suppliers, dependency on only one source becomes important. As the number of suppliers are reduced in JIT system, the suppliers compete and try to carry on their relationships with customers by showing their technological efficiency and loyalty. A healthy communication first between the supplier and its suppliers is a must for JIT purchasing. This communication in Japan, holds both parties responsible for organization of delivery schedules according to JIT rules. If the firms want to select the best supplier, to have a long-run relationship based on mutual needs and trust and to improve quality, they should have work closer with suppliers. In multi-supplier environment this objective can not be reached, but when the purchasing policy is based on only one supplier, this supplier knows that it will lose its job forever if it can not perform as well as to satisfy the customer. Working with few suppliers is preferred because of the reasons below: 1. Developing suppliers is costly and if the number of suppliers is not limited it can not be cost efficient. 2. Close relationships can be established with limited number of suppliers and communication and coordination works well with them. 3. Limited number of suppliers provides cooperation with them and quality improvements are considered as awards 4. Long term relationships are possible for limited number of suppliers. 5. The participation of supplier beginning with product design provides production of high quality products. XI6. As the materials are bought totally from the supplier the supplier can produce high quality products. 7. As the customer has a share of the supplier, the supplier gives close attention to the customer. 8. Deliveries can be adjusted as required, as the orders are given to limited number of suppliers. 9. Establishment of a long-term relationship between the customer and the supplier causes supplier loyalty and reduces the risk of interruption of delivery. Increased cooperation includes joint technology development efforts, partnership in product development, mutual program implementations and continuous training programs to provide high quality standards. For the partnership to be advantageous for both parties the costs should be reduced, on-time delivery should be provided and joint efforts should be performed to renew products. Continuous evaluation of suppliers is as important as selecting the supplier as a duty of purchasing which means to supply the required material with the best price, quality and delivery. The delivery performance of supplier is evaluated by on-time deliveries. So the most important criteria of delivery performance can be denned as high quality material delivery that is made in small lot sizes, in required quantities and on time. The reduction ofset up time and on-time deliveries in small lot sizes decrease the ordering costs. The quality control of the material is done at the source that is the supplier. Materials are not controlled by the buyer and directly sent to the production line. By that way costs of inspection and moving of materials are eliminated. The supplier should provide the quality standards required by the buyer for the materials to be sent directly to the production line. So the buyer has the responsibility of informing its suppliers about quality specifications and training them on quality reliability. This training can be provided by frequent visits to suppliers with technical personnel, quality certificates or special training programs. In JIT, the objective is on time delivery of required quantity of material to the buyer. In JIT buyers support their suppliers to have their facilities or warehouses, physically closer as it reduces transportation costs, helps on-time delivery and regional economic development. When there exists physically long distances contracted transporters should be employed and supply system should be coordinated as a whole to reduce transportation costs. Transporters should be controlled more closely, some improvements should be made and a transportation system harmonious with JIT material schedules should be planned. Instead of producing all the parts inside, buying them from suppliers is in parallel with backward integration. The important thing here is the participation of suppliers in product design as soon as possible and continue cooperation with the buyer during the life cycle of the product. So existing and potential problems will be reduced. For the success of JIT purchasing system, definitive monthly schedules should be sent to the suppliers 2-4 weeks ago and the indefinitive monthly schedules of coming 1-2 months should be sent, too. These schedules should reflect the most possible situations. A deviation of 15-20% will cause distrust of supplier and it can begin to work with inventories and will have less cooperation. In JIT environment transportation firms are accepted as a part of the system, so the success of JIT is dependent upon them. The contracts between the producers and transporters should be made around the on-time delivery and small lot xusizes. Many firms control their operations with JIT system different from classical system and on-time delivery is one of the most important elements of that control. In that study the JIT philosophy and the relations with the suppliers under JIT system has been discussed and a real case of a supplier firm's efforts and implementations to provide on-time delivery to the main firms which are trying to implement JIT system are described. ABC customer analysis and capacity planning improvement project aims to eliminate all the problems resulting in late delivery to customers. Because of that, in the first place the capacity is determined by taking product, machinery specifications, rush order quantities and machine breakdowns into account. Delivery on time to the customers which are classified as A, B and C is the main objective of this project and while reaching that objective no change in capacity is considered. In other words, the objective of the project can be summarized as the fulfillment of promises to the customers. A Group Customers: These are the customers that have a long term relationship ordering in optimum quantities whose products can be easily handled by the machines and make their payments on time. They have a good image and show a continuous development in their sectors. Also they expect high quality products and service. C Group Customers: This group of customers are weaker in financial position and invoiced rarely according to the market conditions. Their order quantities and specifications affect the productivity of the machinery negatively and the supply of required materials is relatively hard. Their orders cause a high inventory burden and their performances are also not very promising in the market. B Group Customers are those customers that are included neither in A group nor in C group. In the project, 40 firms were evaluated under 24 criteria and classified in 3 groups defined above. After that study, importance was given to capacity planning. In the first place, on time delivery was accepted as a more important issue than waste reduction and the software related with order entries was modified to prevent order entries that are in excess of capacity. As a result of these efforts, on time delivery increased from 62,5% to 92,5%. When the orders are in excess of capacity, A group customers have the priority in delivery, but when there exists a problem for A group customers, a committee comprising of production planning and sales personnel decides on delivery. As the firm does not have an activity based cost accounting system, profitability could not be used as a criterion for the ABC analysis. Also the firm does not use the reserve capacity tool since the sales are not so high because of seasonality and the need for reserve capacity is satisfied by adjusting idle shifts. But after the required modifications in the software is made and the advantage of idle shifts is eliminated in XUIthe high season, reserve capacity will be determined and implemented. There are also new projects to implement activity based cost accounting in the near future. Improvements in the existing software will not only provide revising the capacity but also will provide the necessary statistics and information for the continuity of the ABC customer analysis. Kav Ambalaj is at the beginning of customer analysis study, but the results are impressive. For the first quarter the target İs exceeded almost 10%. As the feedback is received, the system will be improved and the results will be better. XIV
Benzer Tezler
- Tam zamanında üretim sistemi ve bir sanayi işletmesinde uygulama çaışmaları
Başlık çevirisi yok
ALİ CEMNUR BAYRAM
Yüksek Lisans
Türkçe
2000
İşletmeGebze Yüksek Teknoloji Enstitüsüİşletme Ana Bilim Dalı
YRD. DOÇ. DR. GÖKHAN ÖZER
- Üretim kaynakları planlaması (MRP II) ve yan sanayi maliyet analizi ve kontrolü sistemi
Manufacturing resources planning (MRPII) and vendor firms cost analysis and control system
SERKAN SANCAN
Yüksek Lisans
Türkçe
1997
Endüstri ve Endüstri Mühendisliğiİstanbul Teknik ÜniversitesiEndüstri Mühendisliği Ana Bilim Dalı
DOÇ. DR. TUFAN VEHBİ KOÇ
- Bir otomotiv yan sanayi işletmesinde hücresel üretim sistemi tasarımı ve çok amaçlı çizelgeleme problemi çözümü
Cellular manufacturing system desing and multi-objective scheduling problem solution in an automotive supplier industry enterprise
SENA AYDOĞAN
Yüksek Lisans
Türkçe
2020
Endüstri ve Endüstri MühendisliğiKütahya Dumlupınar ÜniversitesiEndüstri Mühendisliği Ana Bilim Dalı
PROF. DR. ŞAFAK KIRIŞ
- Tam zamanında üretim sistemi ve Adıyaman ilinde nitel bir araştırma
Just in time production system and a qualitative research in Adıyaman province
ZÖHRE GÜLER
- Tam zamanli üretim sistemleri ve bir israf azaltma uygulama örneği
A industrial establishment is selected in a order to taper pff the waste and execute jit production.
AYHAN KOYUNCUOĞLU
Yüksek Lisans
Türkçe
2007
Endüstri ve Endüstri Mühendisliğiİstanbul Ticaret ÜniversitesiEndüstri Mühendisliği Ana Bilim Dalı
DR. ZAFER UTLU