Optimal control policy for two consecutive operations with time constraints

Abstract

Today, with the advancement of the production line, the queue time constraints become an important instrument to improve the product quality. Proper production control for time constraints not only secures product quality but also improves fabrication productivity.

Achieving high utilization and low rework rate are the important objectives. A good control policy should maintain a balance between these two objectives. In order to achieve this goal, an approximation queuing model of two single servers with a fixed queue time constraint in between is been proposed.

To understand the impact of this project, start from studying the performance of two single servers with fixed time constraint in between. The tandem queue is fed with jobs of a single product type and the service time is constant. In this project assume both servers suffer identically distributed time based pre-emptive interruptions. The objective will validate with an optimal queuing model using Matlab program. The Matlab program is to stimulate the queuing system with different combination of parameter set such as service time between station 1 and station 2, queue length, warm up size, sample size, material cost, mean time to failure (MTTF) and finally mean time to repair (MTTR). This report presents the analysis of the rework rate, loss rate and the safety (Work In Process) WIP level of the queuing system in order to minimize the production cost with considering the trade-off between rework rates and loss rates.