Abstract:
PT. Indo Jaya Equipment is a company that specifically operates in the automotive industry, namely the
manufacture and modification of vehicle bodies. PT. Indo Jaya Equipment, one of the commonproblems often faced by industrial companies is problems with inventory. One way to reduce
production costs is to save raw material supplies to reach optimal levels. The problem in this researchis how to apply the Material Requirement Planning (MRP) approach in controlling rawmaterial
inventory at PT. Indo Jaya Equipment. Even though the company has planned the purchase of rawmaterials according to the number of orders. The company has to buy raw materials again whichmakes the costs of procuring raw materials and storage costs increase. When this happens, the
company has to buy raw materials from other suppliers when the main supplier does not have stock. This can disrupt production because the delivery of raw materials is not according to schedule. The
raw material analyzed in this research is 4 mm x 1200mm x 2400mm iron plate. The analytical methodused is forecasting the use of raw materials in the future using the Least Square method, Multiplicative
Decomposition, and Trend Analysis with the help of Ms. Excel software. Based on the results of
calculating the smallest MAD, MSE and MAPE error values, the method chosen was the Multiplicative
Decomposition method. And based on the research carried out, results were obtained fromacomparison of 3 lot sizing techniques with the most optimal results to be applied with expenditure costs
which include inventory costs and storage costs, namely Part Order Quantity (POQ). Inventory of rawmaterials with a frequency of arrival of 2 times amounting to IDR 15,400,000. With an ef iciency level
of 71% compared to the company's method with an arrival frequency of 7 times Rp. 53,000,000, it is
possible to recommend an option for raw material inventory control methods for companies to produce
ef iciency and minimize total inventory costs.
