Publication: Envanter ve stok kontrol modellerinin incelenmesi ve en iyi sipariş miktarının belirlenmesi üzerine bir uygulama
Abstract
Bu tez çalışması tarafımdan dört bölüm halinde hazırlanmıştır. Birinci bölümde envanter ve stok kontrol modelleri ele alınmış olup, envanter tanımı, maliyeti, politikası, stok miktarı ve stok takibi üzerinde durulmuştur. İkinci bölümde malzeme ihtiyaç planlaması (meterials requirments planing) anlatılmış, devamında MRP sisteminin tasarlanmasında en önemli konulardan birisi olan sipariş miktarlarının belirlenmesi üzerinde durulmuştur. Sipariş miktarlarının belirlenmesinde kullanılan yöntemlerden tek tek bahsedilip, hepsi için ayrı ayrı toplam maliyet hesapları yapılmış ve yöntemlerin performansları karşılaştırılmıştır. Üçüncü bölümde en iyi sipariş miktarının belirlenmesine yönelik bir uygulama yapılmıştır. Askeri alanda faaliyet gösteren bir elektrik motorları fabrikasında parti büyüklüklerinin belirlenmesine yönelik bu uygulamada dünyada en yaygın kullanım alanına sahip kesikli sipariş algoritması ( lot for lot ) Wagner whitin algoritması (WW) en düşük birim maliyet algoritması (LUC) Silver-Meal algoritması kullanılmış ve elde edilen sonuçlar karşılaştırılmıştır. Dördüncü bölüm sonuç bölümü olup, elde edilen sonuçlar değerlendirilmiş. Sonuç olarak firma sipariş miktarını her dönem için hesaplanmış net ihtiyaçlar kadar değil de parti büyüklüğü tekniklerini kullanarak hesapladığı değerleri sipariş miktarları olarak alırsa daha düşük maliyete sahip sipariş politikasına sahip olacağı sonucuna ulaşılmıştır.
This research has been prepared in four sections. In the first section inventory and stock control methods has been defined. Within this section, inventory cost, inventory startegy, stock quantity and stock control are the issues that has been highlighted. Second section describes the Materials Requirement Planning and continiued with the determination of the order quantity which is one of the most significant topics in the scheming of Materials Requirement planning. The methods to determine the order quantity has explained one by one and the total cost analysis has been done for each of the methods together with the comparison of their performances. An example application to determine the most favourable order qantity has beeen done in the third section. The application is aimed to determine the lot quantities in an electric engine manufacturing company for military usage. Wagner Whitin algoritm which has got the widest usage of lot for lot algoritm, the Least Unit Cost algoritm and Silver Metal algoritm has been used and the outcomes has been compared in the section. Fouth section is the conclusion and the outcomes of the research has been evaluated. As a result, it has been found that the particular company in the example, has a lower cost of order strategy when the lot quantities has been considered by using the methods briefly explained in the third section. On the other hand, determining the lot quantity in terms of the net requirements of each particular time period is a higher cost strategy.
This research has been prepared in four sections. In the first section inventory and stock control methods has been defined. Within this section, inventory cost, inventory startegy, stock quantity and stock control are the issues that has been highlighted. Second section describes the Materials Requirement Planning and continiued with the determination of the order quantity which is one of the most significant topics in the scheming of Materials Requirement planning. The methods to determine the order quantity has explained one by one and the total cost analysis has been done for each of the methods together with the comparison of their performances. An example application to determine the most favourable order qantity has beeen done in the third section. The application is aimed to determine the lot quantities in an electric engine manufacturing company for military usage. Wagner Whitin algoritm which has got the widest usage of lot for lot algoritm, the Least Unit Cost algoritm and Silver Metal algoritm has been used and the outcomes has been compared in the section. Fouth section is the conclusion and the outcomes of the research has been evaluated. As a result, it has been found that the particular company in the example, has a lower cost of order strategy when the lot quantities has been considered by using the methods briefly explained in the third section. On the other hand, determining the lot quantity in terms of the net requirements of each particular time period is a higher cost strategy.