THE OUTPUT PROCESSES OF SERIAL PRODUCTION LINES OF GENERAL MACHINES WITH FINITE BUFFERS

Little is known about the interaction among manufacturing subsystems i n a factory. The output of one manufacturing subsystem is usually the input to one or more others in the plant. For example, a production li ne may provide input to another manufacturing stage, a shipping system , or an automated parts conveyor. In all of these examples, the charac teristics of the output from the production line can affect the subseq uent process. This paper examines the output process of a serial produ ction line of N machines with general processing time distributions an d finite buffer capacities. Simulation is used to examine the effects of line length, buffer capacity, and buffer placement on the inter-dep arture distribution and correlation structure (autocorrelation functio n) of the output process of the production line. Results from this ana lysis are useful in setting production line design parameters and in d etermining the extent to which buffer placement can be used to control the variability of the output process, and thereby the amount of work -in-process present in downstream subsystems. Additional insights are provided to help explain why small buffers in production lines are nor mally adequate and to help us better understand the effects of buffers on tightly coupled production systems. By using a variety of processi ng time distributions, previously unknown effects attributed to skew o f processing time are revealed. Since skew can often be reduced or eli minated by operator training, these effects are of particular interest since they can help to quantify some of the benefits of training.