Many manufacturers look for capacity where it is easiest to measure — machine speed and staffing. But a large part of the loss lies in waiting time, changeovers and micro-stops that rarely appear in the daily numbers. This article explains how value stream mapping can make the hidden loss visible.
Why the loss is hidden
Capacity loss is rarely one big problem. It is the sum of many small ones: a couple of minutes' waiting time here, a changeover that takes longer than necessary, a micro-stop that goes unrecorded. Each single occurrence seems insignificant, and so it isn't measured. Together they can make up a substantial share of the available time.
Value stream mapping (VSM) as a method
A value stream mapping follows the product through the entire process and separates the time that creates value from the time that does not. The result is often surprising: the value-adding time typically makes up a smaller share of the total lead time than expected.
The three sources of loss most often overlooked
- •Waiting time — materials, information or decisions that aren't ready when the process is
- •Changeovers — time spent switching between products, often without a standardised procedure
- •Micro-stops — short interruptions below the threshold that are never recorded systematically
From analysis to action
A mapping only has value if it leads to changed behaviour. What matters is not the map itself, but the routines that ensure the identified losses are followed up and removed at the source — and that they don't return when attention moves elsewhere.
To get started yourself, you can use our value stream mapping template and the accompanying VSM guide. If the capacity loss is tied to the machine rather than the flow, systematic OEE improvement is the natural next step.
✓Concrete takeaways
- →Measure lead time, not just machine time — it reveals the waiting time between the steps
- →Record micro-stops systematically — what isn't measured can't be improved
- →Prioritise the biggest sources of loss first — avoid spreading the effort thin
- →Anchor the follow-up in a fixed routine — otherwise the loss returns
Sources and further reading
- Rother, M. & Shook, J. (1999). Learning to See: Value Stream Mapping. Lean Enterprise Institute.
- Womack, J. P. & Jones, D. T. (1996). Lean Thinking. Simon & Schuster.
- Lean Enterprise Institute — lean.org.
The references show the professional basis. Sources are reproduced in their original language.