132 THETOYOTAWAYFIELDBOOK
In Chapters 4 and 5 we discussed the need to isolate variation so that stan-
dardization may be achieved. The following case example illustrates the challenge
of standardizing a task with built-in variation. In these cases, before the task can
be standardized the variation must be separated or isolated from the remaining
portion, which can then be standardized.
Case Example: One Job, Three Different Tasks
The “job” in this case example is to operate two automatic screw
machines, which cut and machine long bars of steel into discrete metal
parts. The operator’s work includes three distinctly different tasks. The
variation inherent in the three tasks makes the job nearly impossible to
standardize.
The first task is to perform in-station quality checks and serve the
machine (removing metal chips and moving finished product). The
operator is required to perform a specific number of part inspections
each hour. The inspections are repeatable in nature, and the task is
repeated within a one-hour time frame (a standard cycle time).
The second task involves loading raw material as needed. This task is
also repeatable in nature, but the cycle time varies, based on the part
being produced and the cycle time of each part produced. The time
variation is between one and two hours.
The third task is to set up and change tooling when worn and between
product changes. This portion of the job is not repeatable within
several hours, and the frequency of this event is highly variable.
The tasks range from fairly repeatable and consistent to very variable
and inconsistent. When blended into one job, it is not possible to
determine a repeatable pattern that can be standardized. To complicate
matters, each operator is responsible for two machines. If one machine
is in setup and the other needs material, the machine in setup will wait.
If both machines are in setup simultaneously, one machine will wait for
attention. In many cases this lost time exceeded several days. If both
machines were operating normally, the first task was not enough to fully
occupy the operators’ time and they had considerable waiting time. This
scenario created waiting time for boththe operator and the machine.
To isolate variation, the work tasks were reassigned. The first task was
assigned to one person who was now responsible for servicing 10
machines and performing the quality checks. The loading of material
was assigned to one operator who was responsible for 10 machines,
and the setup responsibility was assigned to two people for all 10
machines. This reassignment “freed up” an operator, and the team
leader role was created to provide additional support to the line.