Value Stream Mapping: current state, future state, and the gap
Value Stream Mapping (VSM) is how Lean sees end-to-end flow. Current-state map first, then walk the process with a stopwatch, then design a future state that eliminates specific wastes. VSM separates real Lean practitioners from slideware consultants.
What goes on a VSM step
- Cycle time (C/T) — how long the step takes per unit
- Changeover time (C/O) — setup between SKUs
- Uptime % — how often the step is available
- Defect rate % — how often it fails quality
- Wait time — queue time before this step
- Operators — how many people staff this step
The 8 wastes — DOWNTIME
| Letter | Waste | What it looks like |
|---|---|---|
| D | Defects | Scrap, rework, complaints |
| O | Over-production | Making more than downstream needs |
| W | Waiting | Queues between steps — usually the biggest |
| N | Non-used talent | Skill wasted, ideas ignored |
| T | Transport | Unnecessary movement of product |
| I | Inventory | Buffers hiding problems |
| M | Motion | Operator reaching, walking, searching |
| E | Extra processing | Steps that don't add customer value |
Current state — facts only
Walk the process with a stopwatch. Capture actual cycle times, not nameplate. Measure wait time between steps — that's where the biggest Lean wins usually hide. Total process lead time is the sum of cycle and wait. Value-add ratio = sum of cycle / total lead time.
Future state — the gap
Where do you want value-add ratio to go? Which wastes will you attack, in what order? A credible future-state map names the countermeasure against each waste — not just 'reduce inventory.' 'Pull system at Station 4, eliminate 2-day buffer' is a countermeasure.
From map to Kaizen
The future-state map drives the Kaizen event. Each identified waste is a candidate. Pick 2-4, attack them in a 5-day event, then remap. Iterate, don't perfect.