Page 446 - The Toyota Way Fieldbook

416 THE TOYOTA WAY FIELDBOOK

1. The two stages of assembly (Assembly and Secondary Assembly in
Figure 19-7) were combined into a single Assembly & Secondary
Assembly cell (flow where you can).
2. The manufactured component operations (Tube Bending, Stamping)
and purchased components are on a pull system using a super-
market and kanban (pull where you must).

3. One of the manufactured components that had been in batch mode
(the Spun Res., or spun resonator) is built on a machine dedicated to
Toyota with parts flowing through a small first-in, first-out buffer to
1
Assembly. There are three boxes of inventory as compared to 1 ⁄2
days in the old system.
4. A daily order goes to one place—Assembly—and is leveled, with
everything else pulled to Assembly. MRP (Material Requirements
Planning) has been turned off for everything except long lead-time
purchased parts.
The purchased parts supermarket is modeled after Toyota’s system.
There is one central supermarket, and then a “water spider” makes
regular timed routes from the supermarket to the various operations,
delivering parts on a one-hour route. She picks up kanban and manages
the entire kanban delivery system inside the plant. The route repeats
over and over each hour, and there is even detailed standardized work
that shows minute by minute where she will be—like a well-executed
bus or train system. The result was a reduction in material handlers
even though deliveries went from once a day to every hour.

The results in Figure 19-9 are impressive. Complete implementation took
nine months and purchased parts inventory was cut in half, one-quarter
of the floor space was freed up, parts per employee almost doubled, and
overtime was reduced from 252 to 10 hours per week. Bear in mind
that these levels of improvement are possible in a relatively short time
because this plant had previously developed a broad base of lean
capability that allowed Tenneco to work on multiple value streams
simultaneously. While this value stream was being worked on, Tenneco
extended the model line approach to their other main value streams,
which were mostly complete about six months after the original model
line. System-level changes like these are generally far more sustainable
because they drive more significant cultural change.

Are there disadvantages to the value stream approach or is it nirvana?
Obviously, no one approach is perfect. As seen in Figure 19-6, above, the value
stream approach can be time consuming, require leadership of a cross-func-
tional team, and a lot of involvement at all levels; and while the model is being
developed, other managers and team associates are kept waiting to see how it