Determine raw material quantity for multiple station production line

In manufacturing, the work-piece will be processed in multiple stations to produce the finished goods. Each station needs to maintain a certain amount of raw materials and semi-finished products to keep the production run continuously. This stock in each station creates the dead cash flow and large amount of waste for the production. This research aims to find a reasonable amount of stock in each station so that it can not only maintain a smooth production, but also makes the enterprise as a whole in a lean manufacturing environment. To find the best storage strategy, a mathematical model which minimizes work-in-process (WIP) has been worked out considering the takt time, raw materials replenishment time, and cycle time of each station, and considering overproduction as a factor that will effect to enterprise. Sensitive analysis for this model is conducted with the numerical examples provided in this paper.