Optimizing Spare Part Management Through Inventory Policy Efficiency Using Total Cost- Service Level Stochastic Model

Muthmainnah, Salsabila Aminatun (2025) Optimizing Spare Part Management Through Inventory Policy Efficiency Using Total Cost- Service Level Stochastic Model. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Spare parts management is a crucial aspect of maintaining production efficiency and cost control in manufacturing companies. At PTP Inc., spare parts contribute to 87% of stockout conditions, significantly affecting operational performance by increasing production delays, ordering frequency, and holding costs. Currently, PTP Inc. relies solely on a deterministic inventory model, which fails to address the highly variable and intermittent nature of spare parts demand and impacted to company struggles with both overstock and understock issues, which negatively impact total cost performance and customer service levels. To address this issue, this research aims to optimize spare parts inventory policy using four different models: (s,Q), (R,S), (R,s,Q), and (R,s,S). Based on the stockout level, 10 material numbers are plotted and chosen to represent others, with variety result of lumpy, smooth and erratic demand. These models will be evaluated using a total cost and service level approach to determine the most cost-effective strategy by weighting it to 30% (service level) and 70% (Total Cost). The study incorporates stochastic modeling to better handle demand uncertainty by Monte Carlo simulation, ensuring a more adaptive procurement strategy. By leveraging Gurobi optimization software, the research successfully identified the optimal inventory position for each policy, minimizing costs while achieving the company’s target service level of 95% and reducing cost up to 30%. The ultimate goal is to help PTP Inc. reduce its stockout rate to 5%, ensuring better decision-making in spare parts procurement. For critical spare parts, the policy chosen is Policy 1 (s, Q), avoiding the idle of review period. This research contributes valuable insights for procurement department and director by demonstrating how integrating stochastic models with inventory policy optimization can significantly improve procurement strategies. But then, the collaboration of Production Planning and Maintenance are most important since the most impacted of spare parts are their reliability and lifetime.
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Manajemen suku cadang merupakan aspek krusial dalam menjaga efisiensi produksi dan pengendalian biaya di perusahaan manufaktur. Pada 2024, di PTP Inc., suku cadang berkontribusi sebesar 87% terhadap kondisi stockout, yang secara signifikan memengaruhi kinerja operasional dengan meningkatkan delay, frekuensi pemesanan, serta biaya penyimpanan. Saat ini, PTP Inc. hanya mengandalkan model inventori deterministik, yang kurang efektif dalam menangani pola demand suku cadang yang bersifat tidak teratur (lumpy) dan berselang (intermittent), sehingga forecasting saja tidak cukup untuk menyelesaikan permasalahan overstock maupun understock. Untuk mengatasi permasalahan ini, penelitian ini bertujuan untuk mengoptimalkan kebijakan inventori suku cadang dengan mengevaluasi empat policy: (s,Q), (R,S), (R,s, Q), dan (R,s,S). Sepuluh material number dipilih berdasarkan tingkat stockout dan diklasifikasikan (lumpy, smooth, dan erratic) untuk mewakili keseluruhan populasi data. Evaluasi dilakukan dengan pendekatan total biaya dan service level, dengan pembobotan masing-masing 70% dan 30%. Simulasi Monte Carlo digunakan untuk mengakomodasi ketidakpastian demand stokastik, untuk menghasilkan strategi pengadaan yang lebih adaptif. Dengan memanfaatkan perangkat lunak optimasi Gurobi, penelitian ini berhasil mengidentifikasi inventory optimal dari masing-masing policy untuk mencapai target service level 95% serta menurunkan biaya hingga 30%. Secara khusus, untuk suku cadang kritikal, kebijakan terbaik adalah model (s,Q) karena menghindari risiko idle akibat periode tinjauan. Hasil penelitian ini memberikan kontribusi penting bagi departemen pengadaan dan manajemen, dengan menunjukkan bahwa integrasi antara model stokastik dan optimasi kebijakan inventori mampu meningkatkan efektivitas strategi pengadaan. Namun demikian, kolaborasi antara Departemen Production Planning dan Maintenance menjadi faktor penentu utama keberhasilan, mengingat reliability dan lifetime suku cadang menjadi aspek yang paling berpengaruh.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Spare Parts Management, Inventory Policy, Stochastic Model, Gurobi; Manajemen Suku Cadang, Kebijakan Inventori, Model Stokastik, Gurobi
Subjects:	H Social Sciences > HD Industries. Land use. Labor > HD55 Inventory control
Divisions:	Faculty of Industrial Technology and Systems Engineering (INDSYS) > Industrial Engineering > 26201-(S1) Undergraduate Thesis
Depositing User:	Salsabila Aminatun Muthmainnah
Date Deposited:	30 Jul 2025 06:35
Last Modified:	30 Jul 2025 06:35
URI:	http://repository.its.ac.id/id/eprint/123436

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