When you have ghosts, who do you call? The Ghost Busters! So, who do you
call when you have bottlenecks? The Bottleneck Busters, of course! But
who are they? Answer: The people on your own plant floor.
of all, what is a bottleneck? Simply stated, it is a condition in any cell
or work center where the Required Capacity exceeds the Demonstrated Capacity.
Bottlenecks are not stationary constraints. They move all the time. Every
time the product mix changes or the master schedule changes, the Required
Capacity changes. When new products are introduced, a few new people are
hired, equipment ages or processes are improved, the Demonstrated Capacity
changes. The system should discover and identify bottlenecks. The Bottleneck
Buster's role is to find a way to increase the Demonstrated Capacity and
eliminate the bottleneck. (See the archives for a previous article that
defined and discussed Demonstrated Capacity).
cause havoc in a manufacturing company. The symptoms are clear. Lead times
become longer, work-in-process inventory increases and schedules are missed.
Inevitably, expediting becomes rampant, causing poor quality, more rework,
increased scrap and higher costs -- and usually causes an even lower Demonstrated
the informal system, bottlenecks are discovered after work piles up on
the shop floor. When the plant floor managers plead "Just release the work,
get it out on the plant floor and we'll get it out," that's a dead giveaway
that the informal system has taken over! This is an "after the fact solution."
They are depending on visually spotting physical piles of work to discover
the bottlenecks. Sometimes the visual signal for a bottleneck might be
a pile of kanban signals. Unfortunately, in either case the work gets behind
schedule before the bottleneck is discovered and can be reduced. It's an
formal system anticipates bottlenecks by calculating the Required Capacity
before the work (or kanbans) physically piles up on the plant floor and
comparing it to the Demonstrated Capacity. Required Capacity is the work
to be done to meet the master schedule. It can be calculated with simple
techniques such as Capacity Requirements Planning and Resource Requirements
Planning. Visibility can extend out as far as the SOP supply plan or master
schedule planning horizon.
Demonstrated Capacity is simply a measurement of work actually done in
the past. Future Demonstrated Capacity is a prediction of future capability
of the cell or work center. Demonstrated Capacity is a function of how
many hours are worked and the effectiveness of those hours. Better methods,
better tooling, overtime, subcontracting, and hiring more people are a
few ways to increase Demonstrated Capacity. The only limits to increasing
Demonstrated Capacity in the future are time and money. The Bottleneck
Busters are experts at finding ways to increase Demonstrated Capacity --
just look at the end-of-the-quarter miracles!
important principles should be considered when overcoming bottlenecks:
Beware of automated, automatic solutions to overcome bottlenecks. People,
not the computer, must be accountable for overcoming the bottlenecks. Did
you ever notice that they still put windows around the cockpit of planes
in spite of the sophisticated automatic pilot electronics? When flying,
I like the idea of a person, not a compute, being accountable for uneventful
takeoffs and landings. The same holds true for bottleneck accountability.
If a formula or algorithm programmed in the computer is used to solve the
problem, people on the shop floor have a built-in excuse if the solutions
don't work. They claim with glee, "The computer did it!"
The logic of the system must be transparent. Computer programs should give
people data to help them decide how they will overcome the bottlenecks.
But if the information is calculated by mysterious formulas and complex
logic that the Bottleneck Busters don't understand, they have only two
options; blind faith or ignore the software data. The first alternative
can be a disaster! The second alternative means that the company invests
in a formal system, but continues to use the informal system to run the
on the shop floor can be avoided. We have experts all over our factory
floors who know how to eliminate bottlenecks. Give them a credible prediction
of the Required Capacity and I'll bet they know exactly how to avoid the
bottlenecks! Try this in your own company. And send us an email about your