Production Control in Batch and Multi-product Manufacturing Systems under Process Queue Time Constraints
Date Issued
2010
Date
2010
Author(s)
Cheng, Yu-Ching
Abstract
This paper studies the admission control method for different manufacturing system with process queue time constraints. In semiconductor, Thin Film Transistor-Liquid Crystal Display (TFT-LCD), other industries, the waiting time of WIP is limited to upper bound in system, the time constraint is called the process queue time constraint (PQT). When the PQT constraint is violated, a significant scrap cost will be accrued. The queue time constraint makes the production control difficult, production managers need to balance the need for achieving production targets and yield quality.
To raise the productivity, batch process machine is widely applied in manufacturing system. The batch machine can process several jobs to reduce waiting time and improve system throughput rate, the increased productivity will facilitate industries to gain more revenue. To fulfill the variety customer demand, multiple product machine is also broadly used in manufacturing system. The multiple product machine can process different type of jobs to meet customers’ diversified demand, the overall revenue will be increased. Hence, this research focuses the batch process manufacturing system and multiple product manufacturing system. Under the PQT problem, we develop the optimal production control method for the manufacturing systems aforementioned.
We use Markov decision processes (MDP) to formulate a batch process admission control (BPAC) model in batch process manufacturing system under PQT constraint. Moreover, we also propose a dynamic admission selection control (DASC) model in multiple product manufacturing system under PQT constraint. The objectives of our policies are to minimize the sum of inventory holding costs and scrap costs. We also conduct simulation study to verify the robustness of our method. The simulation results reveal that our policies significantly reduce total costs while improving throughput and system utilization.
Subjects
admission control
process queue time constraint
batch process manufacturing system
multiple product manufacturing system
production control
Markov decision processes
Type
thesis
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