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LEAN THINKING: LEAN IN THE
"lean" doesn't apply if you don't have a product line?
By David Dixon (as printed in Fabricating and Metalworking)
A persistent myth pervades the job-shop community. It suggests
that the strategies and tools that have "leaned out" countless
manufacturing operations around the world are simply not applicable
in low-volume, high-mix environments. This article, the first in
a series, aims to debunk the myth, factually and logically, once
and for all.
There are, to be sure, certain problems with the application of
lean tools in a job shop that we will have to address. We want to
offer ideas and suggestions on how to implement lean, and we will
ultimately demonstrate to the shop owner that embracing lean will
provide a true competitive advantage and economic benefits that
provide a decent return on the investment in the implementation
effort. This done, our "lean won't work in the job shop"
myth goes up in smoke, and we can get on with the application of
lean's powerful set of process-improvement tools.
markets we serve drive us to a given manufacturing strategy. Figure
1 illustrates the spectrum of alternatives, from a Make-to-Stock
(MTS) approach on one end to an Engineer-to-Order (ETO) environment
on the other. Assemble-to-Order (ATO) and Make-to-Order (MTO) are
"in between" strategies that cater to different customer
needs. Most MTS and ATO manufactures are original equipment manufactures
(OEMs) with marketing and design capabilities. MTO and ETO companies
are often (not always) suppliers to OEMs.
And herein lies the definition of a job shop: a company with many
OEM customers who buy a wide variety of component parts in relatively
small lot sizes. The degree of repetition is low for any one part
number, and the aggregate demand is "lumpy." Failures
in customers' order-planning processes create crisis conditions
in the job shop, and we measure success by how well we respond to
Now consider that "granddaddy" of all lean applications,
the Toyota Production System. Toyota is clearly an MTS, OEM company—a
far cry from the somewhat chaotic MTO/ETO environment of the small
job shop. Is it any wonder, then, that shop owners and managers
question the applicability of a "Toyota" type system in
their world? Add to that the fact that there have been too many
failed attempts to force-fit the repetitive lean model in the job
shop, and you have the basis for widespread rejection of the whole
The myth has evolved from the notion that there is a rigid template
for implementing lean. Fortunately, there are some who have used
a more flexible approach to achieve tremendous improvements in job-shop
Every manufacturer has the same market driven objectives:
- • Deliver smaller lots more frequently
• Deliver on time
• Cut lead time
• Improve quality
• Reduce total cost
2 depicts the basic lean tool kit (upper part of the diagram) and
the desired outcomes across the bottom. Clearly, these outcomes
support directly the common set of objectives listed above.
The trick is to selectively learn and apply the lean tools that
help to achieve the objectives in a given shop while de-emphasizing
or ignoring those that do not apply.
The Job Shop Lean Application chart on this page speaks briefly
to the purpose of each tool and, in the right hand column, suggests
the role of the technique in the job shop. Note that some tools,
e.g., autonomation, engineered packaging and handling, are not as
important in the job shop as they are in the OEM, repetitive environment.
Other tools, such as takt time/line balancing, focused layouts and
pull systems are adapted to the low volume, high variety shop. And
others, such as setup reduction, 5S workplace organization and error
proofing are particularly important.
note the chart's references (on page 19) to applying lean tools
to improving front-end processes. These activities prepare orders
for release to the floor, and in many shops every order passes through
this process. Delays or errors associated with the front end are
passed on to the shop where the cost of correcting problems escalates
exponentially. Many shop supervisors would tell you that if we could
only fix the problem of late or faulty job packets, the rest would
Thus we have a heavy emphasis on applying lean tools to enable
the timely delivery of perfectly "clean" orders to the
Order-planning requirements are typical of the many differences
between the job shop and the OEM. If orders are repetitive, process
documentation is prepared one time, documented as standard work,
and fine-tuned over time. In the job shop, the critical standard
work is the preparation of process documentation that may only be
used one time.
It is also difficult to dedicate resources in a small shop, so
we may employ virtual cells or the "cell for a day" concept.
Sometimes we use mobile equipment to set temporary cells. A push-pull
variation on true demand pull systems is more common in the job
shop, and we may measure performance to a run rate of planned labor
hours rather that a takt time based on piece-parts. Setup reduction
at constraint resources will be pursued relentlessly, and preventive
maintenance routines will be highly developed. And, of course, we
will use error proofing, both in the front-end processes and in
the shop to "get it right the first time."
There is one underlying objective that we share with the OEM—we
want to enable a flow of work through the shop. Perhaps the OEM
flows parts or products one at a time. We may flow small lots or
orders, but flow we will. As our selective, appropriate application
of lean tools bears fruit, we will become ever more compliant with
the Golden Rules of Flow:
- If you touch it, finish it!
- Flow one piece at a time.
- Flow in one direction.
- Never pass on a defective piece.
- Balance each task to takt time (or a run rate).
There are hundreds of small shops who have discovered the combination
of lean tools that have allowed them to flow their work through
a waste free process. They are dominating their local markets and
putting extraordinary profits to the bottom line.
Isn't it time you did the same?
David Dixon, president of Technical Change Associates, is a registered
professional engineer with more than 35 years' experience in lean
manufacturing, Six Sigma and other improvement initiatives.