Lean teams use VSM to see the whole system before fixing parts of it. It separates value-added time from waiting and points improvement at the biggest delays.
Where it comes from
VSM grew out of the material and information flow diagrams used in the Toyota Production System. Mike Rother and John Shook's workbook "Learning to See" codified the method for wider use.
At a glance
A current-state value stream map
Swipe sideways to see the whole diagram.
How to apply Value Stream Mapping
- 1
Choose a product family
Pick a group of products or services that share most process steps. Map one value stream at a time.
- 2
Walk the current state
Follow the work from customer back to supplier at the gemba. Record each process step, inventory point and handoff.
- 3
Collect data per step
Capture cycle time, changeover time, uptime, batch size and people. Note wait times and queues between steps.
- 4
Draw the information flow
Show how orders, schedules and signals reach each step. Mark where work is pushed rather than pulled.
- 5
Build the timeline
Add a ladder of value-added time against total lead time. The gap shows how much of the flow is waiting.
- 6
Design the future state
Use takt time, continuous flow, supermarkets and leveling to sketch a better stream. Turn the gaps into a dated improvement plan.
Worked example
A team maps how a custom order moves from quote to shipment. The timeline shows a few minutes of actual work inside about ten days of lead time, mostly orders waiting for approval and batching. The future state adds a daily approval slot and smaller batches.
Common mistakes
- Mapping from a conference room instead of walking the actual process.
- Drawing a beautiful current state and never building or executing a future-state plan.
- Mapping too broad a scope, so the map has no clear product family or owner.
When Value Stream Mapping is not the right tool
A value stream map suits one product family with a repeating flow. In very high-mix, low-volume work, start with the most common path or group similar jobs.
It is a planning tool, not an improvement in itself. A map that does not lead to a future state and an action plan has little value.
What a value stream map shows
A value stream map is a one-page picture of how a product or service moves from request to delivery. It shows each process step, the inventory or queue between steps, and the information flow that tells each step what to do.
Under the steps runs a timeline. Its top line adds up waiting time and its bottom line adds up processing time, so the map shows how much of the total lead time is work and how much is waiting.
Value stream mapping template
A basic template has four bands. The top band holds the customer and the supplier, with the planning or control function between them. The middle band holds the process boxes with data boxes underneath. The bottom band holds the timeline.
Each data box usually records cycle time, changeover time, uptime, the number of operators and the batch size. Teams draw the first version by hand with a pencil, then redraw it in a value stream mapping software tool if they want to share or update it.
How to create a value stream map
Pick one product family and walk the process from the shipping end back to the receiving end, so each step is seen from its customer's point of view. Record the data at each step while you are there rather than from reports.
Draw the current state first. Then mark the waste you saw, set a target, and draw a future state that shows flow, pull and fewer handoffs. The gap between the two maps becomes the improvement plan.
Common symbols
Process boxes show each step, with a data box for cycle time, changeover and uptime. Triangles mark inventory. Push arrows, supermarkets and kanban symbols show how material moves.
A timeline along the bottom compares lead time with value-added time. The ratio shows how much of the lead time is spent waiting.
Designing the future state
Learning to See, by Mike Rother and John Shook, guides the future state with a set of questions. They cover takt time, where flow is possible, where to use supermarkets and where to schedule.
Each change becomes a kaizen burst on the map, with an owner and a date. Value stream mapping software is covered in the VSM software category.