Flow Interruption Analysis examines where and why work stops moving through a process.
The interruption may appear as waiting, starvation, blocking, queue growth, detour, or restart.
The objective is to improve flow stability, not merely average speed.
Define the intended flow
Start with the expected sequence.
One-Piece Flow provides the broader Lean principle of moving work in small increments with minimal waiting between steps.
Even processes that cannot achieve literal one-piece flow can still define the intended movement of work.
Observe interruption points
Go to the process and identify where work waits, accumulates, returns, stops, or changes route.
Process Mapping helps make steps, decisions, handoffs, and delays visible.
Do not rely only on average cycle-time reports.
Separate interruption types
Useful categories include upstream starvation, downstream blocking, equipment stop, quality hold, material shortage, and information delay.
Different interruption types require different countermeasures.
Measure duration and frequency
A short interruption repeated 50 times may be more important than one long event.
Capture frequency, duration, location, and operating condition.
Short Interval Control can help detect recurring flow losses during the operating day.
Identify the system effect
Ask what happens downstream when the interruption occurs.
Possible effects include queue growth, missed takt, overtime, expediting, or sequence disruption.
Flow Efficiency helps compare active processing time with total elapsed time.
Interruption often explains why flow efficiency is low.
Investigate recurring causes
Use evidence to identify why the interruption repeats.
Possible causes include unreliable equipment, poor replenishment, uneven workload, approval delay, or excessive batch size.
Bottleneck Analysis helps determine whether the interruption affects the resource that limits system output.
Improve the system around the interruption
Possible countermeasures include material triggers, standard work, buffer adjustment, layout change, maintenance action, or workload leveling.
The countermeasure should match the interruption mechanism.
Common mistakes
Measuring only average cycle time, mixing all interruption types together, blaming the downstream step for queue growth, improving a noncritical interruption while the constraint remains unstable, collecting data without observing the work, and treating every queue as automatically wasteful are common mistakes.
Practical sequence
- define intended flow.
- observe where flow stops.
- classify interruption type.
- measure frequency and duration.
- quantify downstream effect.
- identify recurring conditions.
- test likely causes.
- prioritize interruptions affecting system performance.
- implement targeted countermeasures.
- verify that flow stability improves.
The practical lesson
Flow Interruption Analysis focuses on the moments when work stops moving.
Stable flow improves when repeated interruptions are made visible, classified, and removed at their source.