What a Value Stream Map Shows

A value stream is every action, value-adding or not, that is needed to bring one product or service from the customer's order to the customer's hands. A value stream map (VSM) is a one-page picture of that stream. It shows three things together: how the material moves, how the information that tells each step what to make moves, and how much time the product spends being worked on compared with the time it spends waiting.

The method was made widely known by Mike Rother and John Shook in their workbook Learning to See, published by the Lean Enterprise Institute in 1998. They based it on the "material and information flow" diagrams used inside the Toyota Production System. The icons and the step-by-step method in this course follow that tradition, because it is the one most teams and most software templates use.

Why a value stream map and not a flowchart?

A flowchart shows the sequence of steps and decisions. It is excellent for agreeing how a task should be done. But it usually says nothing about how many parts are waiting between steps, how each step learns what to do next, or how long a part takes to get through. A value stream map adds exactly those things. It is drawn at a higher level: one box is a whole process area, such as "Welding", not one task inside it.

The typical first finding is that a product is being worked on for a few minutes but spends days or weeks in the building. Improving the speed of one machine attacks the minutes. The map points the team at the days: the inventory, the batching and the scheduling that create the waiting.

A short example

Brenlow Engineering makes steel pipe-support brackets. Its managers believed the welding area was the problem, because welders were always busy and orders were late. A value stream walk showed that each bracket received under four minutes of work in total, but spent more than three weeks in the factory. Most of that time was in piles of cut and bent parts waiting for the next step. The welders were busy because they were working on parts the customer did not need yet. The map changed the conversation from "we need another welder" to "we need to stop building parts nobody has asked for".

The figures for Brenlow are invented for teaching. You will build its complete map, step by step, later in the course.