Downtime variability: the impact of duration-frequency on the performance of serial production systems

It is intuitively appealing to measure downtime in terms of total time lost (i.e. frequency times duration). However, the same total downtime can be produced by an infinite number of frequency/duration combinations. This study reports the findings of a computer simulation study on the impact of varying combinations of downtime frequency/duration pairs on performance of serial production systems. The research reported here clearly shows that different downtime frequency/duration combinations affect serial production lines differently even when the total downtime remains equal. Analysis suggests that long duration, infrequently occurring variation has a much more negative impact on system performance than short duration, frequently occurring variation.