بهينه‌سازي مقدار كالاي در جريان ساخت با توجه به عدم ظرفيت يكسان ماشين‌آلات و تعميرات اضطراري در سيستم ‌هاي توليدي پيوسته

Optimizing WIP considering unbalanced machine capacity and emergency maintenance in flow shop systems

افزايش بهره‌وري يكي از عمده‌ترين اقدامات مورد توجه هر سازمان است. تعيين سطح بهينه‌ي موجودي در انبارها باعث كاهش هزينه‌ها و افزايش بهره‌وري مي‌‌شود. در اين مقاله يك مدل رياضي مبتني بر برنامه‌ريزي خطي به‌منظور كاهش ميزان موجودي كالاي در جريان ساخت دستگاه‌هاي توليدي پيوسته با توجه به عدم يكسان بودن ظرفيت ماشين‌آلات از يك ‌طرف و توقفات ماشين‌آلات از طرف ديگر ارايه ‌شده است. از آنجا كه در اين نوشتار از يك مدل رياضي براي بهينه‌سازي استفاده ‌شده، مي‌توان مطمين بود كه ميزان موجودي بين كارگاهي تعيين‌شده در اين روش ايده‌آل بوده و با مثال عددي اين مدل حل ‌شده است. مدل پيشنهادي را مي‌تواند براي تعيين سطح بهينه‌ي موجودي بين كارگاهي در تمامي واحدهاي برخوردار از سيستم توليدي پيوسته به كار برد.

: Warehouses are one of the most important parts of the organizations. Decreasing inventories in warehouses cause reduction in the costs and increase in the productivity if their amount is calculated in a scientific manner. the production systems are devided into job shop and flow shop systems. In the job shop production systems, some places are usually considered as warehouse for work in processing parts. In the Flow Shop systems, usually there is not any special place to keep this kind of parts, and in fact, there should not be any place as warehouse to keep the work in process as inventory. So, calculation of WIP is very important in this production systems, because if they are not determined correctly, they will cover a great amount of the area in the production lines and will distribute the workers for doing their duty in the best manner and a messy place will appear in this area. So, work in process (WIP) is an important issue in flow shop systems. How much the amount of this stock should be is one of the factors that the management is faced with. Increasing this inventory causes blocking of the money, wasting area, and increase of expenses; on the other hand, more material handling causes reduction in the quality of the commodity. In this paper, a Linear Programming approach for decreasing work in process in flow shop production systems is introduced regarding unbalanced machine capacity and emergency breakdowns. By an optimization method, it can be claimed that work in process is optimized. This model is solved by some numerical examples. Because the approach is an optimistic method, it can be claimed that the result, which is the amount of inventory and overtime and quantity of the production, is the best. The proposed model can be used in every continuous production system.