|
|
| Kanban: Are You ReadyMarch 1, 2004 I recently had an executive at a large
organization tell me “We are going to implement a Kanban system first, and
then we will think about a Lean implementation.” This seems to be common in
companies today as they pick and choose the tools of Lean but do not look at
them from a systems standpoint. Lean tools like 5S, SMED, Kanban, TPM etc., are
very powerful but are so often misused due to improper thought process. Many
companies look to Toyota and the success they have had with a Kanban
implementation and think it is the answer to all their problems, but what they
fail to realize is to be successful they must have stable production processes.
Organizations should look at the success Toyota has had through development of
the Toyota Production System (TPS), but they need to keep in mind that it has
taken them 50 years. Let’s look at Toyota. At
the 2003 Automotive Parts System Solution Fair, held in Tokyo, June18, 2003,
Teruyuki Minoura, then-managing director of global purchasing, Toyota Motor
Corporation, talked about his experiences with TPS (the Toyota Production
System), and what it means for suppliers and for the future of the In simplest terms, just-in-time is “all about producing only
what’s needed and transferring only what’s needed,” says Minoura. Instead
of the old top-down “push” system, it represented a change to a “pull”
system where workers go and fetch only what is required. Tools, including the
kanban (information card), andon (display board), and poka yoke (error
prevention) were developed to implement the pull system. But, Minoura warns
“simply introducing kanban cards or andon boards doesn’t mean you’ve
implemented the Toyota Production System, for they remain nothing more than mere
tools. The new information technologies are no exception, and they should also
be applied and implemented as tools.” There
are several barriers in production processes that companies should look at as
they begin a Kanban implementation. Short
die changeover and machine set-up time are critical to respond quickly to a
production signal. If die changeover and machine set-up time is long, it makes
the system less responsive. Toyota’s officials believe that short die
changeover and machine set-up times have been responsible to a large extent, for
the success of kanban implementation at Toyota. The reduction in die changeover
and machine set-up times also reduces the production lot size. Short die
changeover and machine set-up time offers the necessary flexibility for a pull
system. A study conducted on the US automotive industry in 1997, reported that
the die changeover time for Chrysler, Ford, and GM was nine times more than that
of Toyota. Changeover cost being proportional to changeover time, the
recommended economic lot size is three times that of Toyota. Additional finished
goods inventory is required for a pull system to operate with long die
changeover times to offset the effect of slow response time and reduced resource
availability. Therefore, Toyota has an edge over the rest to implement the pull
system. Another
roadblock to implementing a pull system is varying production schedules. Since a
pull system causes production to start only when there is a demand for the
product, a large variation in demand will cause production levels to change. A
study at Toyota’s assembly plant showed that a hybrid system outperformed a
pure pull system, in the case of variable demand. The
third obstacle to pull system implementation is production variability.
Production variability is a result of problems in the production process. Two
common reasons for stalling of production are equipment downtime and quality
stops or rework. The reliability of the production process is very important to
respond quickly to a production signal. The
fourth obstacle, large batch size, needs to be reduced to implement a pull
system. Large batch sizes do not provide the production flexibility
required for an effective pull system. The
fifth obstacle is a critical bottleneck in the production process. Applying the
Theory of Constraints approach, the bottleneck is scheduled first, and the rest
of the processes are forced to meet this schedule. This system is superior to a
pure pull system. The
sixth and the last obstacle is long lead times. Long lead times prevent the
produced parts from reaching their destination in time. For example, a pull
system may not work when there are vast geographical distances separating
assembly plants and suppliers. An analysis of Toyota’s Motomachi plant reveals
that almost all its suppliers are within 30 kilometers of the plant. This
physical proximity with suppliers reduces lead times. Efforts
to implement a pull system before making the necessary process improvements will
fail to bring about the desired benefits. The implementation of kanban is not
the only reason for Toyota’s success. The process improvements, prerequisites
for the implementation of kanban, have resulted in Toyota’s world-class
production system. Click here to subscribe to our free e-newsletter Learning to Lean and receive three articles like this one each month. About
the Author David McBride is co-founder of EMS Consulting Group (http://www.emsstrategies.com), a Carlsbad, CA based engineering and management consulting firm. David has a BS in Mechanical Engineering from Ohio State University. He has a successful track record in the development and implementation of FMEA and Design for Manufacturability programs at several organizations and has greatly reduced Manufacturing costs through the utilization of Lean Manufacturing, Kaizen Events, and Manufacturing System Analysis. He has also been highly successful at developing and executing New Product Introduction processes, and Staffing and Capital Equipment Plans. To contact David about this article, send an e-mail to davidm@emsstrategies.com. | ||||||||||||||
Send mail to
webmaster@emsstrategies.com with
questions or comments about this web site.
|
