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Finite Buffer Closed Lines - Diagnostics

As we saw, a finite buffer system can be considered as a constrained version of an infinite buffer system. Thus, the performance (throughput for any given WIP level) of the infinite buffer system is an upper bound on that of the finite buffer case. So, we can still use the concept of the practical worst case to establish an internal benchmark for the finite buffer system.  However, now a potential reason for performance worse than the practical worst case is inadequate buffer space.

• Example: Consider the line we saw before, with bottleneck rate 1/1.2 min. and the raw process time equal to 1 + 1 + 1.2 + 1 = 4.2 min. For a WIP level of 5 jobs and with no inter-station buffers we saw the throughput was 0.53 jobs/min. Using the diagnostic tool, we see that the practical worst case throughput for the line with a WIP level of 5 is 0.56 jobs per minute. So we conclude that the performance of the line is not very good.  However, if we add a single buffer between each of the station in the line, the throughput jumps to 0.62 jobs/minute, which is better than the practical worst case.  The diagnostic tool is telling us that the original line is under buffered.

In order to carry out diagnosis on lines click here.

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