Paper Title
Reducing Inventory Costs by Determining an Appropriate Order Quantity Using Economical Order Quantity Principles Case Study of the Production Plant Machine

The objective of this research was to investigate the Economic Order Quantity of raw materials to serve production properly. This study used historical data from 2022 to identify the cause of the problems by applying “Fishbone Diagram”, and the ABC Classification System was applied to classify the material product groups. The Economic Order Quantity method followed, and the “Basic Model” was employed to find out the Economic Order Quantity. The total cost was compared between the current operations’ total cost and total cost determined by considering the EOQ concept. The results of this research revealed that the cost of group “A”, 9 items, compared with the original cost, was reduced to THB 128,737 per year. Group “B” was reduced to THB 76,982 per year and group “C” was reduced to THB 122,757 per year. In conclusion, the reduction of the total cost was reduced to THB 358,226 per year. accounting for 52.17 percent of the original total cost. Keywords - Inventory Cost Reduction, Fishbone Diagram, ABC Classification, Economic Or-Der Quantity