Processing time
The time a piece is actually being worked on. Everything else in lead time is waiting.
Formula
In practice
A station's cycle time is derived from its work elements and never stored as a figure somebody typed. Elements that overlap machine time are excluded, because a gauge check performed while the machine runs does not extend the cycle and does not occupy the operator. Where a process has several machines, the per-unit figure divides by the machine count; the time a unit resides in the process does not.
An observed cycle time can be recorded alongside, and where the two differ by more than 10% the gap is reported. It is never used as an input and never overwrites the derived figure — a stopwatch reading that disagrees with the elements is a finding about the element list, and resolving it silently would delete the finding.
How this is calculated
Cycle time is derived from work elements, never stored:
cycle time = Σ element times, excluding elements that overlap machine time
per unit = cycle time / machine count
manual content = Σ elements that are neither machine time nor overlapping it
The overlap rule matters: a gauge check performed while the machine runs does not extend the cycle and does not load an operator.
An observedCycleTime, where recorded, is compared against the derived figure.
A gap above 10% is reported. It is never used as an input and never overwritten.
changeover loss = duration × frequency per day
available for run = net available − changeover loss
capacity = available for run / per-unit cycle time
bottleneck ⟺ capacity < required passes
Methodology — Cycle time and capacity
Common questions
Does processing time include waiting?
No. Processing time is the sum of the cycle times on the route — the part of the wait that is work. Everything else a unit spends on the map is queue time, and the two are added to give lead time. Keeping them apart is what makes process cycle efficiency mean anything.
My stopwatch says something different. Which figure wins?
The derived one, and the disagreement is published rather than resolved. A gap above 10% usually means an element is missing from the list, or that one recorded as overlapping machine time is not actually overlapping it.
This definition is the one the product itself shows, read from its interface catalogue at build time.