Penentuan Lot Size Permintaan dan Perencanaan Pendistribusian Coca-Cola Softdrink dengan Metode Integer Linear Programming di PT. Coca Cola Bottling Indonesia Distributor Wilayah Surakarta
Nur Laili - - Fak. Teknik
Surakarta Distributor of Coca Cola Bottling Indonesian Company is coca cola softdrink distributor for retailer in Surakarta and surroundings. Completing retailer demand in every single month during of the year 2006 there were stockout in 6 items of coca cola softdrink that would cause a backlog. Stockout is the condition where retailer’s demands are not fulfilled because when an order came, the inventory didn’t enough to fulfill the demand. The stockout causes are an unoptimal product availability, retailer’s demand forecast error and uncertainty of retailer’s demand. By determining the optimal demand lot size and distribution planning from Ungaran to it’s distribution channel of Surakarta, this case can be solved.
Coca cola softdrink’s demand lot size and distribution plan are determined by these steps. First, demand forecasting with the proper method. Second, calculate the safety inventory level and then design an integer linear programming model. Demand forecast improvement is done in order to help channel distributor estimate the retailer’s demand accurately and determining safety inventory properly to anticipate stockout. Designing integer linear programming model to determine an optimal demand lot size and scheduling coca cola softdrink’s distribution from Ungaran to it’s distribution channel of Surakarta for January till March 2007. It’s objective function is to minimize the amount of ordering cost, transportation cost and inventory holding cost and it’s constraints are warehouse and transportation capacity and inventory proportional.
Outputs of integer linear programming model are coca cola softdrink’s optimal demand lot size and inventory. The other output is coca cola softdrink’s distribution schedule for January till March 2007. The implementation of these ouputs will reduce Rp. 6.860.574,03 of company cost and also avoid the stockout of completing retailer’s demand.
Key words : lot sizing, supply chain, integer linear programming , stockout.