How Do I Find the Bottleneck?
When everyone is busy, every station looks like the problem. The bottleneck is the one resource that limits what the line ships, and an hour lost there is an hour lost for the whole line. Finding it comes first for almost every other fix.
What Is Usually Going On
- The bottleneck moves with product mix, so last month's answer may be wrong.
- Utilization reports show every resource as busy, which hides the one that sets the pace.
- Standard cycle times differ from real ones, so the math points at the wrong station.
- Stops and rework at one station hide inside shift totals.
- A shared resource (test stand, oven, inspector) limits the line but is not on the routing.
How to Fix It
- Walk the line and look for the queueWIP piles up in front of the constraint and stations after it wait. Walk at different times of the shift.
- Time each stationTen or more cycles per station, stops included. Use observed cycle time, not the standard.
- Compare to taktTakt = available time / demand. Any station with effective cycle time over takt cannot keep up. The one furthest over is the constraint.
- Use effective capacityEffective cycle time = cycle time / (availability x yield). A fast station that is down often can still be the constraint.
- Load shared resourcesList anything used by more than one line or part: test, paint, heat treat, inspection, a crane. Load each with all the demand it sees.
- Confirm with a testAdd a person or a short shift at the suspect station. If line output rises, you found it. If WIP just moves, look downstream.
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Common Questions
Is the bottleneck always the slowest machine?
No. It is the resource with the least effective capacity against the demand it sees. A fast machine that is down often, or that every part routes through, can be the constraint.
Can a line have more than one bottleneck?
At any moment one resource limits output. With mix changes or unstable stations the constraint can move between two or three. Stabilize those first.
Bottleneck or constraint: which term is right?
On the floor they mean the same thing. Constraint is the theory of constraints term, and it can also be a policy, like a batch rule, not just a machine.
What do I do once I find it?
Keep it running, feed it good parts only, cut its setups, and move off any work it does not need to do. Then pace everything else to it.