Once the
systems constraint is identified, it must be subjected to the red carpet
treatment. Nothing in your system is
more important than the constraint— nothing!
Once you have this information, you must decide how to best manage the
constraint. If the output from your
entire system depends solely on the output of the constraint, then it certainly
merits special considerations. One of
those considerations is to exploit the constraint, which is Step 2 of the Five
Focusing Steps. Exploitation means that
you evaluate the process to get the most out the constraint activity.
Rarely is a constraint being utilized at, or near, the maximum that it
can do. The exploitation effort means
looking for things that the constraints can stop doing. This could be an excellent opportunity to
employ the Interference Diagram (ID) to define the interferences that stop you
from getting more from your constraint. You may want to implement Lean concepts
to reduce waste or Six Sigma to better control variation and quality. It might also mean taking actions as simple
as keeping the machine, or process, busy during break time and lunch time, or
perhaps implementing a second shift or a third shift, or even off-loading work
to non-constrained processes or resources.
Exploitation does not mean buying a new machine or adding more
resources, at least not yet. It simply
means finding ways to get more out of the current process than you are
currently getting. There is a very high
probability that during the exploitation exercise, the constraint capacity
could be improved above and beyond the capacity of the next constraint in the
system. If such is the case, then go
back to Step 1 and redefine the constraint.
In a normal improvement effort, this repeating cycle between Steps 1 and
2 might be completed many times before the system is stabilized. When the system becomes stable, then go to
Step 3 in the Five Focusing Steps and ratify the subordination rule to
synchronize the product flow. The end result is to stabilize and synchronize
the system, and then focus on the constraint.
Let the non-constraints work as required to produce sufficient quantities
to keep the constraint busy.
The second
consideration is to make sure the constraints are busy all the time. Never let the constraint run out of work to
do. If the constraint stops or slows
down, then the entire system will stop or slow down. The best way to accomplish this objective
is to make sure there is always work in the queue in front of the
constraint. In other words, create a
buffer of work in front of the constraint.
The entire system output has total dependency on the constraint output,
and constraint output is directly proportional to system output. Think in terms of the right amount of work,
in the right location and at the right time.
The system
constraint not only determines the amount of throughput you can achieve, but it
also determines the correct amount of work-in-process (WIP) inventory that
should be maintained in the system. The
correct inventory level will be reached almost by default when system
subordination is actively pursued and implemented.
In my next post, we'll discuss the "rope' of Drum Buffer Rope.
Bob Sproull
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