Page 189 - The Toyota Way Fieldbook

Chapter 7. Leveling: Be More Like the Tortoise Than the Hare 165

allowance for variation. The variation method would be defined so it
was consistent (standardized variation).

Analysis of the production data revealed the ratio of finishes was 75 per-
cent stained to 25 percent solid colors. The burnished jobs (the more
difficult ones) accounted for approximately 25 percent of the total stain
jobs. For solid colors, the split was nearly even, with slightly more light-
colored (easy) jobs. This allowed us to create a primary leveling factor
for establishing mix based on the ratios of finish colors and types. Since
the actual daily mix did not necessarily match the averages, there were
secondary conditions added to the pattern. For example, the regular
pattern was:
STU, STU, SOLL, STU, STU, STUB, STU, SOLD, STU, STU
STU Stain, unburnished
STUB Stain, burnished
SOLL Solid, light color

SOLD Solid, dark color
But because the workload for solid light color and unburnished stain
was similar, they could be substituted on the pattern. The goal was to
create as consistent a workload as possible, while processing the cor-
rect ratio of each type job.
The second layer of the pattern was the individual components. The
team identified that the trim work should always be the first item of any
job because of the special processing needed. The small parts went at
the end of a job because they tended to have a low workload and
provided a “spacer” between jobs to allow for color changes, etc. In
addition, two empty racks were sent through between jobs to provide
an empty zone to prevent overspray from job to job. A pattern was
developed that adequately mixed the size and surface area combinations
of each job. Like the color application, some of the categories were
similar and could be substituted as defined (the standardized variation).
The pattern for components was: trim—cabinet—doors—cabinet—
drawers—shelves—doors—cabinets—drawers/doors—repeat as needed—
miscellaneous parts—space—space (next job) trim . . .
Secondary rules were established based on the finish type (because of
workload). For example, cabinets were placed two to a rack if small,
and one if large (or one only of any size for burnished and dark fin-
ish). Doors were six to a rack for unburnished and light colors, four to
a rack for burnished and dark colors. The same logic was applied to
drawers and shelves.
In this case example, the production volume was difficult to define.
The number of pieces, racks, and jobs all had variation. The company