Adjietama, Mochammad Novrizal (2025) Optimasi Pengelolaan Persediaan Suku Cadang di PT Petrokimia Gresik Dengan Pendekatan Metode Lagrange Multiplier. Undergraduate thesis, UPN Veteran Jawa Timur.
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Abstract
Spare parts inventory is one of the critical components in supporting the operational continuity of manufacturing companies, including PT Petrokimia Gresik. However, in practice, there is often a mismatch between actual needs and the amount of inventory stored, such as the overstock issue found in A283-A plate materials with thicknesses of 8mm, 10mm, and 12mm. This overstock leads to several problems, including increased storage costs and inefficient warehouse space utilization. This study aims to optimize spare parts inventory management using the Lagrange Multiplier method. The research utilizes purchase and usage data of plate materials from March 2024 to February 2025. The Lagrange Multiplier method is applied to determine the optimal order quantity while considering warehouse capacity constraints, and the results are compared with the company’s current inventory approach. The findings show that the total inventory cost using the company's method amounted to IDR 185,458,780, whereas using the Lagrange Multiplier method reduced the cost to IDR 65,279,469—resulting in a savings of IDR 120,179,311 or approximately 64.8%. Additionally, forecasting was carried out for the period of March 2025 to February 2026 to support future procurement planning. This research provides practical contributions for more efficient inventory decision-making and demonstrates the applicability of the Lagrange Multiplier method in managing spare parts with irregular demand patterns.
| Item Type: | Thesis (Undergraduate) | ||||||||
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| Subjects: | T Technology > TA Engineering (General). Civil engineering (General) | ||||||||
| Divisions: | Faculty of Engineering > Departement of Industrial Engineering | ||||||||
| Depositing User: | MOCHAMMAD NOVRIZAL ADJIETAMA | ||||||||
| Date Deposited: | 20 Jun 2025 03:48 | ||||||||
| Last Modified: | 20 Jun 2025 03:48 | ||||||||
| URI: | https://repository.upnjatim.ac.id/id/eprint/38547 |
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