MODEL PENJADWALAN BATCH PADA MESIN TUNGGAL YANG TERDETERIORASI DENGAN MEMPERTIMBANGKAN BIAYA INVESTASI UNTUK PERBAIKAN KUALITAS PROSES
Abstract
Penelitian ini mengembangkan model penjadwalan batch pada mesin tunggal yang terdeteriorasi dengan mempertimbangkan biaya investasi untuk perbaikan kualitas proses. Pada sistem yang terdeteriorasi, status sistem akan mengalami perubahan dari terkendali menjadi tak-terkendali dengan laju tertentu. Dalam kondisi tak-terkendali, probabilitas sistem untuk memproduksi non-conforming item akan lebih besar. Perbaikan kualitas proses produksi dilakukan untuk mengurangi probabilitas non-conforming item, sehingga ongkos kualitas yang ditimbulkannya akan berkurang. Model yang dikembangkan berusaha meminimasi total ongkos sistem produksi, yang terdiri dari ongkos persediaan, ongkos kualitas, dan ongkos investasi perbaikan kualitas proses. Dengan model ini, permasalahan penjadwalan dipecahkan secara analitik untuk menghasilkan solusi yang optimal. Model ini dapat menentukan probabilitas non-conforming item setelah perbaikan proses, ukuran batch produksi, dan jumlah batch yang meminimasi total ongkos. Hasil penelitian ini menunjukkan bahwa besarnya tingkat perbaikan kualitas proses mempengaruhi ukuran batch. Dalam penelitian ini, model diuji dengan menggunakan contoh numerik yang dibangkitkan secara hipotetik.
Kata kunci: penjadwalan, batch, proses produksi, kualitas, deteriorasi.
ABSTRACT This research develops a batch-scheduling model on a deteriorating single machine that considers investment cost for process quality improvement. In the system considered deterioration occurs, causing the system to shift from in-control state to out-of-control state in a certain rate. In out-of-control state, probability of the production system producing non-conforming items tends to be greater. Process quality improvement is performed to reduce the probability of producing non-conforming items, so that the resulted quality cost can be reduced. The objective function to be minimized in the model is total production cost, which consists of inventory cost, quality cost, and investment cost for process quality improvement. Batching and scheduling problems are solved analytically by the model so that optimal solutions can be obtained. The model can determine optimal probability of producing non conforming items, batch sizes, and number of batches as well as the optimal schedule which minimize total cost.This research indicates that batch sizes are influenced by process quality improvement level. In this research, the model has been tested using several hypothetical numerical examples.
Keywords: scheduling, batch, process production, quality, deterioration.
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