Value stream mapping

What it means

Value stream mapping is a lean method that maps the entire flow of materials and information from a customer's order to delivery. It shows where value is added and where waiting, inventory, transport or unnecessary steps occur.

The result is a simple map with standard symbols showing the individual processes, the inventory between them, the information flow and time data. The key insight comes from comparing the time actually spent working on the product with the total lead time, which is usually many times longer.

The method comes from the Toyota Production System and is a basis for speeding up processes and cutting costs. It helps reveal bottlenecks and waste that stay hidden when departments are viewed separately, because they arise mainly at the hand-offs between them.

How it works in practice

Mapping starts with the current state: the team walks the process on site, records steps, times, inventory and waiting, and draws the information flow, such as orders and schedules. The aim is to map reality, not how the process is supposed to work according to procedure.

A future state is then designed to remove waste, for example by introducing a pull system and elements of just in time, combining steps or reducing waiting. The gap between the two states becomes an action plan that is implemented step by step in the spirit of kaizen.

The method also works outside manufacturing, for example in administration or accounting. A map of document processing from receipt of an invoice to booking and payment often shows that the document spends most of its time waiting for approval, hand-over or missing data rather than being processed.

What to watch out for

A map alone improves nothing. If mapping is not followed by implementing changes and regular review, it remains a nice poster on the wall. Owners, deadlines and measurable targets, such as a shorter lead time, must be set.

It is easy to focus on one part of the process and optimise it at the expense of others. According to the theory of constraints, it makes most sense to improve the part that limits the whole flow, otherwise savings elsewhere will not show up in the overall result.