I. INTRODUCTION
Managing the activity within the supply chain area is equal with several interrelated business that need to be optimized in purpose to depress the cost and increase the profit. The substantial aspects that most take the role are distribution and production planning. The considerations of integration between both of them are leading the company to have several goals such as minimizing the sum of holding cost, backorder cost, production cost, setup cost, capacity change cost, and unused capacity cost while satisfying the demand over specified time horizon [1], or in other words the output of production planning should be calculated precisely because it will become the input for distribution process. In consequence to achieve all the goals, the production planning will highly related with the manufacturing process which are based in 8 manufacturing plants whose location are centralized inside the industry area in Gresik and also the supply policies which are generally based on geographical
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These aspects will be followed by several constraints that should be satisfied in order to fulfill the real condition inside the industry. The constraints can be defined as capacity for each plant, capacity for each type of transportation mode, capacity for ship loader and unloader, working hours/ day, inventory cost, shortage cost, penalty cost for exceeding the congestion allowance, etc. By considering the constraints, the company should achieve the objectives by completing the needs of subsidiary fertilizer corresponding to government rules, optimizing the plant utilization, and also optimizing the company profitability.
II. METHODOLOGY
Problem that will be discuss in this research solved by distribution requirements planning method (DRP). These are the following steps used.
A. Rough Mater Production Scheduling (Monthly Time