Komatsu's Spare-parts Service Level and Day of Inventory Improvement for PT. MTN

PT UTB faced problem of its fluctuating demand of spare parts that make its inventory very high. The purpose of this research to increase the service level to meet its target at 80% and reducing days of inventory to reach below 50 days. The method used in this research used five whys analysis to find the root cause of the problem. Then, conducting forecasting using moving average method through several time series. Economic Order Quantity (EOQ) also was calculated to identify the best method to achieve the research objectives. The Human Factor Analysis and Classification System (HFACS) method is used to analyze the causes of human error in the ordering process based on human error and the role of the organization in fulfilling performance, as well as to obtain recommendations for prevention. Task analysis also was used to analyze the process of ordering spare part to improve it lead-time. The results showed that the moving average method and economic order quantity (EOQ) was able to make the stock more effective and efficient and increasing service levels and decreasing days of inventory (DOI). The Vendor held stock (VHS) system is used as a solution in improving service level measurements and increasing the speed of supply of spare parts to PT. MTN.