Flow and Schedule

My Production Line Is Behind Schedule

Every line falls behind at some point. The gap usually starts as a few lost hours at one station and grows quietly until it shows up in the schedule review. The way out is to find where the hours are lost, not to push every station harder.

What Is Usually Going On

  • One station, the constraint, loses time to stops, starving or blocking, and the whole line runs at its pace.
  • Work is released by the schedule, not by what the constraint can finish, so WIP and lead time grow.
  • The plan uses standard hours the floor has never hit.
  • Shortages stop jobs partway and units get set aside.
  • Absences leave key stations short and nobody is cross-trained to cover.

How to Fix It

  1. Size the gapUnits owed x constraint cycle time = hours to recover at the constraint. That number, not total labor hours, is the real gap.
  2. Find the constraintWalk the line. It is the station with work waiting in front of it and idle stations after it. Confirm with observed cycle times against takt.
  3. Protect the drumKeep the constraint running through breaks, lunch and shift change. Hold a small buffer in front of it. Inspect before it so it never works on bad parts.
  4. Stop releasing ahead of itRelease work at the pace the constraint finishes it (drum-buffer-rope). Extra releases only add WIP.
  5. Put added hours at the constraintOvertime or added heads raise output only there. Hours added anywhere else build WIP.
  6. Re-plan to demonstrated rateIf the gap holds after recovery, it is a capacity question. Size it in FTE or machine hours and take it to the planning review.
Make shop (asset-bound)
The constraint is usually a machine. Recover machine hours: run it through breaks, add a shift on that machine only, cut its setups, move work to an alternate machine.
Assembly shop (labor-bound)
The constraint is usually labor at a station. Move trained people to it, split its work, and have kits complete before the shift starts.

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Common Questions

Should I just add overtime?

Only at the constraint. Overtime on stations that already have spare capacity builds WIP and spends hours without adding output.

How do I know which station is the constraint?

Look for the queue in front of it and starved stations after it. Then check that its cycle time, with stops included, is the longest against takt.

How long will recovery take?

Hours owed at the constraint divided by the extra constraint hours you can add per week. If that is longer than the customer will wait, reset the date now.

Why do we fall behind again after we catch up?

The cause was not fixed. If the constraint keeps losing time to the same stops, the gap returns. Track its losses by cause and work the top one.