Value stream mapping and flow

A current-state map documents how the value stream actually runs today, including its waste, inventory build-up and disconnected steps, so you can see where flow stops. A future-state map designs how it should run after specific lean improvements you can make within 6 to 12 months, with continuous flow, pull and less inventory. The first shows what needs fixing; the second sets the target and the roadmap.

In a pull system no process produces anything until the process downstream of it signals that it needs material. Production follows actual consumption instead of a forecast, which removes the overproduction, excess inventory and waiting that push scheduling creates. Pull is one of the core tools of the just-in-time pillar of the Toyota Production System.

Material lead time (getting raw materials procured and delivered), customer lead time (from the customer's order to delivery), production lead time (the time to make the product) and cumulative lead time (the total across the whole process).

A yamazumi chart is a stacked bar chart of the work at each workstation or operator. Each bar is a station, each segment in it is a task, and the segment's height is that task's cycle time. It makes bottlenecks and uneven workloads easy to see, which is where line balancing starts. Yamazumi is Japanese for “to stack up”.