Group: Murat Ercan, Ahmet Umut Durmuş, Zelina Genel, Ogün Davutoğlu, Merve Civelek

The firm that we have been conducting our System Design projet with is TAI-TUSAŞ which is a leading aerospace industry. Its purpose of existence is to produce for Turkish Air Force and to provide support to Turkish Air Force. In the project, thick panels of project based production are selected in the pilot area in which transformation for lean manufacturing is intended. Thick panels are produced in two different routes in the system. While the main produciton route is mechanical route, since its capacity is not sufficient to meet the demand, chemical route is also present as an alternative route. In the weekly visits to company, system dynamics and processes are observed and inventory holding, setup and extra shift costs are specified as conditions that are improper to lean manufacturing. When these are taken into consideration, we have defined our problem definition as the lack of an inventory management system which assures that assembly never stops and which is agile to customer requirements as well as being proper to lean manufacturing philosophy. After that, mathematical model which minimizes overall cost is conducted. In the model constructed, dynamic and static lot size options with different scenarios are reflected with several versions of model. In addition to this mathematical model, outputs of static lot size models are taken as inputs to simulation model to compare the performance measures.