General design rules for the allocation of buffers in closed serial production lines

Graduation date: 2007One of the classic problems in industrial engineering is the buffer allocation\ud problem. The objective of the buffer allocation problem is to maximize some line\ud output, typically throughput, through the allocation of buffers throughout the\ud production line. Previous work in this area has focused on either determining\ud general design rules or developing heuristics to determine optimal buffer\ud placement. Most of this work was done on production lines which were assumed\ud to have an unlimited supply of jobs to the first workstation and an unlimited\ud storage space after the last workstation (open production lines).\ud The purpose of this research was to study buffer allocation in closed production\ud lines and focus on the validation and development of general design rules for\ud buffer placement. Balanced and unbalanced lines were studied with workstations\ud representing manual stations, and then with workstations representing automated\ud machines.\ud The general approach taken was to first identify an existing buffer allocation rule\ud established for open lines and then determine the corresponding rule for closed\ud production lines. Next, a set of experiments were designed to test the closed\ud production line design rule. Finally, the design rule was validated, modified, or\ud reformulated.\ud The findings of this research indicate that an even buffer allocation is optimal for\ud balanced closed production lines. It also showed similar behavior to open\ud production lines when a bottleneck is present, but the effect of the bottleneck is not\ud as strong. Also, differences between reliable and unreliable lines were observed.\ud Finally, the rules developed seemed to be consistent for short lines as well as long\ud ones.\ud Several of the rules developed in this research can be utilized immediately in the\ud design of closed production lines. Also, because of the lack of literature on closed\ud production lines, it will serve as a good first step into the understanding of the role\ud of buffers in closed production lines