Integrated Production And Maintenance Scheduling Optimization With Sequence Dependent Setup And Machine Breakdown Consideration

HELMY ANDAMARI K, Ir. Nur Aini Masruroh, S.T., M.Sc., Ph.D., IPM., ASEAN.Eng

2022 | Tesis | MAGISTER TEKNIK INDUSTRI

Frekuensi kerusakan dan biaya Corrective Maintenance (CM) dan Preventive Maintenance (PM) merupakan pertimbangan penting dalam menerapkan kebijakan pemeliharaan mesin dalam produksi. Penelitian ini dilakukan pada sebuah produksi elektronik yang memiliki gangguan frekuensi dipelajari untuk menyeimbangkan pemeliharaan dengan produktivitas. Dalam penelitian ini, integrasi inovatif penjadwalan produksi dan pemeliharaan diusulkan untuk mempertimbangkan trade-off dari Corrective Maintenance (CM) dan Preventive Maintenance (PM) secara bersamaan. Model matematika Mix Integer Non-Linear Programming (MINLP) dengan fungsi tujuan untuk meminimalkan total biaya, yang terdiri dari biaya pemeliharaan yang diharapkan, biaya setup, biaya produksi, biaya persediaan, dan expected income loss. Beberapa variabel keputusan yang digunakan seperti interval Preventive Maintenance (PM), sequence-produk, dan kuantitas produk. Berdasarkan data historis kerusakan mesin dalam produksi tersebut di atas, periode breakdown diasumsikan mengikuti distribusi Weibull dan parameter bentuk dan skalanya diestimasi menggunakan Maximum Likelihood Estimation (MLE). Beberapa skenario dibangun untuk mengevaluasi model berdasarkan kasus kerusakan mesin aktual di perusahaan yang menggunakan mesin cetak injeksi untuk produksi. Parameter mengenai produksi diekstraksi dari penelitian sebelumnya dengan mesin yang sama dan karakteristik produksi yang sama. Hasil percobaan menunjukkan bahwa metode yang diusulkan mampu mengoptimalkan biaya berdasarkan jarak antara pemeliharaan preventif. Terutama, penambahan pemeliharaan preventif mungkin tidak lagi menghemat biaya terutama ketika pemeliharaan korektif telah mencapai batas untuk diminimasi

The frequency of breakdown and costs of corrective and preventive maintenance are important considerations of applying the maintenance policy in the production. In this work, an electronic production which has frequency breakdown was studied to balance the maintenance with the productivity. In this research, an innovative integration of production and maintenance scheduling was proposed to consider the trade-off of the corrective and preventive maintenance simultaneously. This work defined a Mix Integer Non-Linear Programming (MINLP) mathematical model with the objective function that is to minimize the total cost, consisting of the expected maintenance cost, setup, production, inventory, and expected income lost. Multiple decision variables such as the length between the preventive maintenances, product sequence, and quantity of product were studied. Based on the historical failure data in the above mentioned production, the breakdown period is assumed to follow the Weibull distribution and the shape and scale parameter of it was estimated using Maximum Likelihood Estimation. Multiple scenarios are built to evaluate the model based on the actual machine breakdown cases in a company that used an injection molding machine for production. Parameters regarding the production were extracted by previous research with the same machine and same production characteristic. The experimental results show that the proposed method is able to optimize the cost based on the length between the preventive maintenances. Especially, the addition of preventive maintenance might not be cost-effective especially when the corrective maintenance has reached the limit

Kata Kunci : Scheduling, Mathematical Modelling, Sequence-Dependent Setup, Maximum Likelihood Estimation