In this posting we will continue our
discussion on integrating Lean and Six Sigma with the Theory of Constraints by
focusing on the basic implementation steps I typically use. It’s important to remember that one of the
key prerequisites for any improvement initiative is to create a satisfactory level
of organizational stability.
Typically, the first step in this integrated
methodology is to develop a SIPOC Diagram followed right away with either a
Value Stream Map (VSM) or a Process Map (P-Map). It has been said that in order to create a
better future state, you must first understand what’s happening within the
current state and I do support this statement.
The primary reasons I start with mapping the process are to assist in
the identification of the system’s constraint and to better understand the
system’s flow issues. The VSM allows us
to see, first-hand, individual process cycle times and inventory stack-up,
which is normally directly in front of our constraint while the Process Map
allows us to run different simulations that confirms the constraint and
validates our improvements to enhance flow.
Many times I create a hybrid P-Map and add cycle times and inventory to
it. In this step I also evaluate all
policies and procedures that are in place that could and do form barriers to
enhanced flow.
Once the maps have been created, I normally
perform a value analysis on each step of the mapped process. I first identify value-added steps as those that
(1) moves an item through the process and changes it, (2) is something the
customer sees as valuable and is willing to pay for it, and (3) is done right
the first time. If the step in question
satisfies all three of these requirements, it’s considered value-added and I
color code it as green. If the step does
not satisfy these three conditions, it is considered non-value-added and is colored
either red or yellow. It’s yellow if it
is considered, non-value-added but necessary meaning that it is mandated by
some regulation and cannot be eliminated.
It’s colored red if it is not mandatory and is clearly wasteful. My experience tells me that a team seeking to
correctly evaluate each step in the mapped process for its value-added
component, sometimes has difficulty with the value analysis because they typically
can’t see what they are doing as not adding value.
Once the value analysis is complete, generally
my next step is to create a Future State Map (FS-Map) which is the same process,
but now being free of the waste that can be eliminated. It is not always easy for a team to develop a
FS-Map because the members many times don’t like to leave their comfort zones
and as a result resist changing it.
When the Future State Map is complete, I then
usually have the team work on quantifying/estimating the new cycle times and overall
lead time of this future state process. In
addition, it is important to identify the location of the constraint in this
new process.
Since performance metrics are intended to
motivate behaviors, I also review the performance metrics that are in place to
make sure that they will, in fact, motivate the right behaviors. Performance metrics like operator efficiency
and equipment utilization only serve to produce excess inventory which
negatively impact cycle and lead times.
If metrics like this exist, then I know that unless they are eliminated
or changed, the improvement effort will be negatively impacted. Having said this, both efficiency and
utilization are quite effective if they are measured only in the
constraint. The metrics I choose for
non-constraints are tied directly to how well the constraint is being supplied. The performance metrics also tell us to how
impactful our improvement efforts have been.
I frequently use run charts to plot these metrics so that trends and
cause and effect relationships can be observed in relative real time status.
In my next posting we’ll continue our
discussion on the subtleties of this important integration,
Bob Sproull
No comments:
Post a Comment