Determining Inventory Policy in Remanufacturing Industry for Heavy Equipment Component

Hakim, Rasyid Aiman (2026) Determining Inventory Policy in Remanufacturing Industry for Heavy Equipment Component. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Pengelolaan persediaan spare part disposal pada kegiatan remanufaktur menghadapi tantangan akibat pola permintaan yang tidak pasti dan tidak teratur. Penelitian ini bertujuan untuk merancang kebijakan persediaan yang sesuai untuk spare part disposal pada perusahaan remanufaktur alat berat (PTX) serta menentukan parameter persediaan yang diperlukan untuk meningkatkan efisiensi persediaan sekaligus meminimalkan kekurangan dan kelebihan persediaan. Penelitian dilakukan terhadap 30 spare part kritis representatif dari komponen AHD menggunakan data permintaan historis periode Januari–Desember 2025. Karakteristik permintaan diklasifikasikan menggunakan metode ADI–CV², dengan ketidakpastian permintaan direpresentasikan melalui fitting distribusi probabilitas dan simulasi Monte Carlo. Dua kebijakan persediaan stokastik, yaitu continuous review (s,Q) dan periodic review (R,S), kemudian dikembangkan dan dibandingkan menggunakan metode normalisasi berbobot yang menggabungkan biaya persediaan (70%) dan fill rate (30%) menjadi satu skor kebijakan. Hasil penelitian menunjukkan bahwa 26 dari 30 spare part (87%) memiliki pola permintaan erratic, mengindikasikan tingginya variabilitas permintaan disposal di PTX sehingga pendekatan stokastik lebih sesuai dibandingkan pendekatan deterministik. Berdasarkan skor kebijakan berbobot, kebijakan (s,Q) terpilih untuk 27 dari 30 spare part (90%) karena memberikan respons lebih baik terhadap fluktuasi permintaan dan biaya total lebih rendah, sementara kebijakan (R,S) terpilih untuk 3 spare part sisanya (10%), di mana peningkatan fill rate yang diperoleh melampaui kenaikan biayanya. Secara keseluruhan, kerangka kebijakan persediaan stokastik yang diusulkan memberikan PTX dasar pengambilan keputusan pengisian ulang yang sistematis dan kuantitatif, mendukung ketersediaan spare part sekaligus mengendalikan biaya persediaan.
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Inventory management of disposal spare parts in remanufacturing operations is challenging due to uncertain and irregular demand patterns, compounded by reliance on external procurement rather than internal return cores to fulfil replenishment needs. This study aims to design an appropriate inventory policy for disposal spare parts in a heavy equipment remanufacturing company (PTX) and to determine the inventory parameters, namely order quantity, reorder point, review period, and order-up-to level, needed to improve inventory efficiency while minimizing both stock shortages and excess inventory. The research analyzed 30 representative critical spare parts from the AHD component using historical demand data from January to December 2025. Demand characteristics were classified using the Average Demand Interval–Coefficient of Variation (ADI–CV²) method. Demand uncertainty was represented through probability distribution fitting and Monte Carlo simulation, generating forecasts for the planning horizon of Weeks 49–96. Two stochastic inventory policies were then developed and evaluated for each spare part: continuous review (s,Q) and periodic review (R,S), with parameters determined through grid-search optimization. The two policies were compared using a weighted normalization method that combines normalized total inventory cost (70%) and normalized fill rate (30%) into a single policy score. The results show that 26 of the 30 spare parts (87%) exhibit erratic demand patterns, while the remainder are classified as smooth and lumpy demand, indicating that disposal demand at PTX is highly variable and better suited to stochastic rather than deterministic inventory approaches. Based on the weighted policy score, the continuous review policy (s,Q) was selected as the preferred policy for 27 of the 30 spare parts (90%), as it provided better responsiveness to demand fluctuations and lower total cost, while the periodic review policy (R,S) was preferred for the remaining 3 spare parts (10%), where the gain in fill rate outweighed its higher inventory cost. Overall, the proposed stochastic inventory policy framework provides PTX with a systematic, quantitative basis for replenishment decision-making, supporting spare-part availability while controlling inventory-related costs and reducing reliance on intuition-based stocking practices.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	kebijakan inventori, remanufaktur, alat berat, (s, Q), (R, S), inventory policy, remanufacturing, heavy equipment, (s, Q), (R, S)
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:	Rasyid Aiman Hakim
Date Deposited:	27 Jul 2026 02:23
Last Modified:	27 Jul 2026 02:23
URI:	http://repository.its.ac.id/id/eprint/137767

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