Ordering Size Optimization of Raw Material to Minimize Inventory Costs using Wagner-Within Algorithm and Silver-Meal Methods

Abstract

Inventory is one of the current assets that can be classified as company assets. But in reality, inventory often turns into an operational problem that can affect the company's overall performance. This problem occurs due to the incorrect determination of the amount of inventory. Both excess and shortage of inventory can lead to cost overruns. This study applies the Wagner Whitin Algorithm and the Silver-Meal method in the lot-sizing process and the ABC (Always Better Control) method in determining the classification of raw materials at PT. X. Using the ABC method, it is known that the ADC-12 Ingot item has a very significant effect to inventory. Inventory optimization using the Wagner Whitin Algorithm and the Silver-Meal method resulted in the optimal frequency of ordering ADC-12 Ingots is 9 times and the total inventory cost is 994,098,000 IDR as well as inventory cost savings of around 18,403,180 IDR or 1.8% of the cost of existing inventory.