Optimal design of automatic transfer lines with two stations

Abstract

This thesis describes some methods of analyzing two stage transfer lines with a finite interstage storage buffer. Automatic transfer lines, defined as an integrated system with a number of workstations, interstation storage buffers, automatic transfer device and a control system, play a major role in mass production systems. Due to high capital investment needed for an automatic transfer line, greater care should be taken in its design so as to optimize the system performance. One way to control the system performance is to control buffer storage between successive stations, and so we give attention to the control policy of the buffer storage. To control the work-in-process inventory in two stage transfer lines, we propose dual limit switches that control the system using two parameters, R and r. Under the policy, preceding station is forced down when the inventory level in the buffer reaches R until the level falls to r. We apply the policy to several cases as follows : First system consists of unreliable stations in which the processing times are random variables. Second system has no failures but random processing times. Deterministic processing times and random failures are considerd in final system. For each feature of system, we analyze the relationships between the system parameters (processing times, failure/repair times and buffer control parameters, i.e., R and r) and system performances.