Production Control in Multi-product Systems with Common Machines under Process Queue Time Constraints
Date Issued
2016
Date
2016
Author(s)
Chen, Yu-Ting
Abstract
This research develops a dynamic scheduling method for multi-product production systems under process queue time (PQT) constraints, wherein waiting time between consecutive processing steps is constrained by predefined upper limits. If the waiting time of a work-in-process (WIP) violates the corresponding PQT constraint, the WIP may be scrapped or have to be reworked due to quality concern. Machine reliability is another concern in the research. Random machine failure in the system may leads to higher risk of scrap and the increase of cycle time. Thus an effective control method with real time machine reliability considerations is important. First, admission control method of two-product production system is developed using the technique of Markov decision process. The objective is to minimize total expected waiting and scrap costs. In the system having more than two products, a heuristic is developed based on two product model. Through the 3 types of experiment design, simulation analysis were implemented. The result of simulation indicates that both two-product model and heuristic used in multiple product system could improve total cost effectively.
Subjects
production control
machine reliability
queue time constraints
common machines
heuristic
Markov decision process
Type
thesis