Notice that each of these loops is a complete closed loop of material and infor-
mation flow. Material flows toward the customer and information flows backward
to trigger the next order from the immediate customer. Each loop can be inde-
pendently worked on from a lean perspective, and the supermarkets buffer one
loop from minor disruptions while another is being changed. A set of “kaizen
bursts,” specific point kaizen activities, are needed to stabilize the process.
Kaizen projects are not replaced by the value stream approach. Individual
processes must be stabilized and variation removed through kaizen projects. A
particularly challenging problem of process variation might benefit from a sophis-
ticated Six Sigma project. Nor does it replace the lean tools approach since lean tools
are needed to implement each piece of the future state value stream—cells, kanban,
etc. What it does do is put the use of these tools and process improvements into a
broader perspective—the material and information flow as a system. It also impacts
the sequence in which implementation occurs. There is often a tendency to imple-
ment one tool at a time, for example, to do quick changeover across the plant. In
the value stream approach you work pull loop by pull loop and do whatever is
required to stabilize, create flow, standardize, and incrementally level that particu-
lar loop. In some cases you may have the resources to work on multiple loops in
parallel, and in other cases you may want to work on them sequentially.
412 THETOYOTAWAYFIELDBOOK
Characteristics
“Learning to see” method
Select product family
Current & future state maps
Develop detailed action plan (“loop by loop”)Project management approach
Visual management (“glass wall process”)STRENGTHS- Efforts are well-integrated within a larger
view - Multiple benefits to value stream are
common - Results typically well-quantified and
tangible - Experience with lean as a system
TRAPS- Can be time consuming
- Fluff—if no follow-up
- Requires large involvement to be
effective - Wide variability in execution
- Can be difficult to identify product
families and value streams in certain
contexts - Others outside of model line are not
directly involved.
Figure 19-6. Strengths and traps of the value stream model line approach