A bottleneck is the condition that limits finished work now; it may be a machine, setup, inspection step, material shortage, outside process, information gap, or scheduling decision.
Trace the Queue Before Naming the Constraint
A growing queue, long wait, late work, repeated expediting, blocked downstream operations, and limited alternate routing can all point toward the limiting condition. Follow representative jobs far enough to see whether the same point controls completion.
Was the job actually ready to enter production?
Where did released work wait, and for what input?
Which condition governed completed good output?
Did the change improve the promised completion?
Expect the Constraint to Move
In high-mix work, the limiting condition can shift with product family, material, outside processing, staffing, downtime, inspection demand, or the schedule. Compare representative routings before declaring one machine the permanent answer.