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| Toyota and TPM (Total Productive Maintenance)May 1, 2004 One of the most recognizable symbols in modern manufacturing is the “TPS House” diagram as shown below. The diagram is a simple representation of the Toyota Production System (TPS) that Toyota developed to teach their supply base the principles of the TPS. The foundation of the house represents operational stability and has several components, one of which is Total Productive Maintenance. Working with little inventory and
stopping production when there is a problem causes instability and a sense of
urgency among workers. In mass production, when a machine goes down, there is no
sense of urgency; excess inventory will keep the operation running while
maintenance fixes the problem. In Lean production, when an operator shuts down
production to fix a problem, the line will soon stop producing, creating a
crisis and a sense of urgency. A properly implemented and maintained Total
Productive Maintenance System (TPM) will provide the needed stability for Lean
production. A little more than thirty years ago, an
automotive supplier company in Japan (Nippondenso) realized that until you
address and systematically eliminate the causes of poor equipment performance,
you cannot deliver to your customers “just in time,” improve quality levels,
lower operating costs, or improve profits. In 1969, the ideas of Total
Productive Maintenance, facilitated by Seiichi Nakajima, helped take the Toyota
Production System to the next level. Since the Toyota Production System was
focused on the absolute elimination of waste to reduce manufacturing cost, TPM
was designed to systematically identify and eliminate equipment losses
(downtime, inefficiency, defects). In implementing Lean manufacturing practices,
machine availability plays an important role. Preventive maintenance is a key
aspect in ensuring machine availability. This practice achieves maximum
efficient usage of machines through total employee involvement. Toyota has created an organizational
culture that encourages employee participation, which is essential for
successful TPM. Group activities are promoted among the shop floor team members.
The knowledge base of all the employees is used to improve equipment reliability
and productivity thereby lowering maintenance and operating costs. Two other
important aspects of TPM are training and open communication between operators
and engineering. Production personnel are trained to perform routine
maintenance. The traditional approach to preventive
maintenance is a clear-cut division of labor. ·
Machine operators perform routine
maintenance functions. ·
Maintenance technicians are responsible
for specialized maintenance and for improving maintainability. ·
Engineering is responsible for improving
the process. This practice is not capable of
achieving the TPM targets, as there is a lack of communication between operating
and maintenance teams. Nippondenso came out with an alternative
approach of appointing a machine technician (MT) that supports communication
between operators and maintenance. The responsibilities of the MT were to
perform minor maintenance and repair tasks. These MT’s underwent classroom
training on tool finishing and fitting as well as on the job training. On the
job training gave them exposure to machines and helped them gain expertise in
their area. There are two different types of
philosophies of TPM. Firstly, there is the centralized maintenance approach.
This requires maintenance personnel to be cross-trained, thus providing
flexibility of using a number of workers for scheduling maintenance tasks. This
flexibility is essential because as workers move up in seniority level there is
a tendency to opt for convenient shifts instead of third shift. The second approach is decentralization.
As personnel become more experienced in one functional area, they gain more
expertise. Sometimes it requires 6 months of training before a person becomes
proficient in a new area. Thus frequent job rotations may result in
under-utilization of skills gained through training. A good example of this type
of approach is at Honda Motors for its three departments – suspension
assembly, facilities and engine assembly. Each department has a separate
maintenance team. The reasons for this shift were the need for 12 to 18 months
of training in each area, and local regulations required maintenance to take
place only on weekends and shutdowns. Toyota has a centralized maintenance
function with cross-trained employees. The benefits of decentralized maintenance
are derived from the use of MT’s. These MT’s are experts in their areas.
However, availability of limited maintenance personnel necessitates
cross-trained employees. Toyota also collects data for analysis
and trend establishment. Sufficient data on the trend and pattern of
equipment’s performance should be available for identifying and setting up
standards and procedures for preventive maintenance. This data would also be
useful in determining costs of preventive maintenance and repairs,
run-to-failure versus preventive maintenance, and failure history. Organizations also need to evaluate the impact of organizational structure and processes on preventive maintenance. Change in these can have an overwhelming impact on employee morale, efficiency, and effectiveness. As Toyota has shown, preventive maintenance management calls for long-term commitment to the goal and pays dividends in the long run. 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. | |||||||||||||||||
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