Multi-Project Scheduling Cost Optimization in a Machine Manufacturer Engineer-to-Order

Authors

Farizal Farizal, Departement of Industrial Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424, IndonesiaFollow
Amar Rachman, Departement of Industrial Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424, Indonesia
Tifani Tandean, Departement of Industrial Engineering, Faculty of Engineering, Universitas Indonesia, Depok 16424, Indonesia
Sumarsono Sudarto, Departement of System Cybernetics, Faculty of Engineering, Hiroshima University, Hiroshima 739-8527, Japan
Katsuhiko Takahashi, Departement of System Cybernetics, Faculty of Engineering, Hiroshima University, Hiroshima 739-8527, Japan

Abstract

This paper discusses the utilization of mixed integer linear programming (MILP) model to optimize cost for multiproject scheduling in a machine maker company. The objective is to minimize total project’s penalty cost and labor cost. The model formulated shows how to achieve the objective i.e. whether to use outsourcing or overtime to finish all projects. The model of multi-project scheduling was solved by Branch & Bound algorithm coded in Lingo 14.0 software. The case study shows that if a company wants to minimize lateness, it should use overtime instead of outsourcing, which minimize total lateness of projects by 144 days or 73.5%. Whereas, if a company wants to optimize cost, they should use outsourcing instead of overtime, which reduces total cost of about 10,873,000 IDR or 28.5%. These results indicate that the model developed is applicable for optimizing multi-project scheduling.

Bahasa Abstract

Optimasi Biaya Penjadwalan Multi-Proyek pada Industri Pembuatan Mesin berbasis Engineer to Order. Paper ini membahas tentang penggunaan model mixed integer linear programming (MILP) untuk mengoptimalkan biaya dari problem penjadwalan multi-proyek pada industri pembuatan mesin. Industri ini dicirikan dengan adanya keterlambatan dalam memenuhi pesanan sehingga menyebabkan adanya biaya pinalti dan tambahan biaya pekerja. Karena itu tujuan dari studi ini adalah meminimalkan kedua biaya tersebut. Model yang dibangun dan dipecahkan dapat menunjukkan bagaimana mencapai tujuan tersebut yaitu melalui outsourcing (alih daya) atau melalui lembur. Model penjadwalan multi-proyek ini dipecahkan dengan menggunakan algoritma Branch & Bound yang telah di-coding dalam software Lingo 14,0. Hasil dari studi kasus yang menggunakan model ini menunjukkan jika sebuah perusahaan ingin menekan keterlambatan maka sebaiknya digunakan lembur bukan alih daya. Penggunaan lembur pada studi kasus dapat menekan keterlambatan multi-proyek hingga 144 hari atau 73,5%. Tetapi, jika perusahaan ingin menekan biaya maka alih daya harus digunakan. Dengan jalan ini perusahaan dapat mengurangi biaya sebesar 10.873.000 IDR atau 28,5%. Hasil ini menunjukkan model yang dibangun dapat digunakan sebagai model generic pada penjadwalan industry multi-proyek pembuatan mesin.

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Recommended Citation

Farizal, Farizal; Rachman, Amar; Tandean, Tifani; Sudarto, Sumarsono; and Takahashi, Katsuhiko (2016) "Multi-Project Scheduling Cost Optimization in a Machine Manufacturer Engineer-to-Order," Makara Journal of Technology: Vol. 20: Iss. 1, Article 3.
DOI: 10.7454/mst.v20i1.3050
Available at: https://scholarhub.ui.ac.id/mjt/vol20/iss1/3