to “external” (performed while the saw continues to add value) was
borrowed from the quick changeover technique. These changes were
easy to implement, and the cost was minimal.
Out-of-cycle losses were the secondary focus: primarily, reductions in
time for blade change (quick changeover) and in cleaning time. The
blade change time was reduced from 10 minutes per change (average
two times per shift) to 2 minutes, and cleanup time was reduced
from 30 minutes to 15 minutes per shift.Reduce Variability by Isolating It
Reduction of variability is the key to achieving stability. Variability comes in
two forms:
- Self-inflicted variability—that which you control.
- External variability, which is primarily related to the customers, but also
to suppliers and to the variation that is inherent to the product itself (dif-
ferent sizes, shapes, and complexities). External variability may not be with-
in your ability to change. However, you can build systems to compensate
for the effects of the variability, mitigating the impact.
A common example of self-inflicted variability is the way many companies
apply resources—people and equipment. Many companies that operate with
the “island” method—with each operation working independently of others—
have no way to fill a position if an employee is absent. This includes vacation,
which is a plannedoccurrence. In most companies, planned and unplanned
absences amount to between 10 and 20 percent of workdays. During these
occurrences, planned work is not completed, workers are shifted around to the
“hot” jobs, and other work—much of it already in process, thus wasting the
time and effort already expended—is left to wait. Once this first domino falls, a
chain reaction begins of chasing the hottest jobs and shifting resources (now
peopleandmachines), all of which magnifies the variation.
The problem with variation is that once it gets started and an “adjustment”
is made, it sets off additional waves of variation, making it difficult to return to
“normal.” We should note here that many people incorrectly believe that a lean
process is rigid and inflexible because the ability to make “adjustments” ran-
domly is removed. We will explore this in Chapter 6, but for now we can say
that the idea is that a standard condition will manage planned occurrences such
as absences, and that response plans will handle unplanned events such as
equipment failure—without negative consequence to the customer, and with a
quick return to the standard method.