A New approach to sheduling shifting bottlenecks in job shop production systems

ABSTRACT MSc THESIS A THEORY OF CONSTRAINTS APPROACH TO BOTTLENECK SCHEDULING IN JOB SHOP PRODUCTION SYSTEMS B. GULSUN K. SARIOGLU DEPARTMENT OF INDUSTRIAL ENGINEERING INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor: Assoc. Prof. Rızvan EROL Year:200I, Pages: 158 Jury: Assoc. Prof. Rızvan EROL Assistant Prof. Funda YILDIRIM Assistant Prof. Arzu GÜÇRAY In this study, the bottleneck shiftiness problem faced especially in job shop production systems with product-mix changes or variations in production environment is investigated and a dynamic production scheduling and control algorithm is developed. Based on the Management with Constraints approach, it is proposed to control the possible bottleneck resources and schedule the production around these resources. In case of bottleneck shiftiness, a new scheduling algorithm, a modified version of the DBR (drum buffer rope) technique, is developed to control the production dynamically. The proposed new dynamic scheduling algorithm aims to reduce work in process levels, the ratio of positively late jobs, and the average flow time. This developed algorithm are compared with the well-known dispatching rules (EDD, FCFS, STR, MOPNR, MWKR, S/RO, SD, LWKR, SPT) using simulation experiments. Simulation results indicate that the developed algorithm outperform the stated dispatching rules especially in terms of ratio of positively late jobs and work in process levels. Simulation experiments use the productiion data collected at a large textile firm. In addition to the current production data, simulation experiments are conducted for varying job arrival rates and due dates. Key Words: Job-shop production, Dynamic scheduling, Bottleneck scheduling, Bottleneck shiftiness