The 7 Manufacturing Wastes
August 29, 2003
Waste elimination is one of the
most effective ways to increase the profitability of any business.
Processes either add value or waste to the production of a good or
service. The seven wastes originated in Japan, where waste is known
as “muda." "The seven wastes" is a tool to further categorize “muda”
and was originally developed by Toyota’s Chief Engineer Taiichi Ohno
as the core of the Toyota Production System, also known as Lean
Manufacturing. To eliminate waste, it is important to understand
exactly what waste is and where it exists. While products
significantly differ between factories, the typical wastes found in
manufacturing environments are quite similar. For each waste, there
is a strategy to reduce or eliminate its effect on a company,
thereby improving overall performance and quality.
The seven wastes consist of:
1. Overproduction.
Simply put, overproduction is to manufacture an
item before it is actually required. Overproduction is highly costly
to a manufacturing plant because it prohibits the smooth flow of
materials and actually degrades quality and productivity. The Toyota
Production System is also referred to as “Just in Time” (JIT)
because every item is made just as it is needed. Overproduction
manufacturing is referred to as “Just in Case.” This creates
excessive lead times, results in high storage costs, and makes it
difficult to detect defects. The simple solution to overproduction
is turning off the tap; this requires a lot of courage because the
problems that overproduction is hiding will be revealed. The concept
is to schedule and produce only what can be immediately sold/shipped
and improve machine changeover/set-up capability.
2. Waiting
Whenever goods are not moving or being
processed, the waste of waiting occurs. Typically more than 99% of a
product's life in traditional batch-and-queue manufacture will be
spent waiting to be processed. Much of a product’s lead time is tied
up in waiting for the next operation; this is usually because
material flow is poor, production runs are too long, and distances
between work centers are too great. Goldratt (Theory of Constraints)
has stated many times that one hour lost in a bottleneck process is
one hour lost to the entire factory’s output, which can never be
recovered. Linking processes together so that one feeds directly
into the next can dramatically reduce waiting.
3. Transporting
Transporting product between processes is a
cost incursion which adds no value to the product. Excessive
movement and handling cause damage and are an opportunity for
quality to deteriorate. Material handlers must be used to transport
the materials, resulting in another organizational cost that adds no
customer value. Transportation can be difficult to reduce due to the
perceived costs of moving equipment and processes closer together.
Furthermore, it is often hard to determine which processes should be
next to each other. Mapping product flows can make this easier to
visualize.
4. Inappropriate Processing
Often termed as “using a sledgehammer to crack
a nut,” many organizations use expensive high precision equipment
where simpler tools would be sufficient. This often results in poor
plant layout because preceding or subsequent operations are located
far apart. In addition they encourage high asset utilization
(over-production with minimal changeovers) in order to recover the
high cost of this equipment. Toyota is famous for their use of
low-cost automation, combined with immaculately maintained, often
older machines. Investing in smaller, more flexible equipment where
possible; creating manufacturing cells; and combining steps will
greatly reduce the waste of inappropriate processing.
5. Unnecessary Inventory
Work in Progress (WIP) is a direct result of
overproduction and waiting. Excess inventory tends to hide problems
on the plant floor, which must be identified and resolved in order
to improve operating performance. Excess inventory increases lead
times, consumes productive floor space, delays the identification of
problems, and inhibits communication. By achieving a seamless flow
between work centers, many manufacturers have been able to improve
customer service and slash inventories and their associated costs.
6. Unnecessary / Excess Motion
This waste is related to ergonomics and is seen
in all instances of bending, stretching, walking, lifting, and
reaching. These are also health and safety issues, which in today’s
litigious society are becoming more of a problem for organizations.
Jobs with excessive motion should be analyzed and redesigned for
improvement with the involvement of plant personnel.
7. Defects
Having a direct impact to the bottom line,
quality defects resulting in rework or scrap are a tremendous cost
to organizations. Associated costs include quarantining inventory,
re-inspecting, rescheduling, and capacity loss. In many
organizations the total cost of defects is often a significant
percentage of total manufacturing cost. Through employee involvement
and Continuous Process Improvement (CPI), there is a huge
opportunity to reduce defects at many facilities.
In the latest edition of the Lean Manufacturing
classic Lean Thinking, Underutilization of Employees has
been added as an eighth waste to Ohno’s original seven wastes.
Organizations employ their staff for their nimble fingers and strong
muscles but forget they come to work everyday with a free brain. It
is only by capitalizing on employees' creativity that organizations
can eliminate the other seven wastes and continuously improve their
performance.
Many changes over recent years have driven
organizations to become world class organizations or Lean
Enterprises. The first step in achieving that goal is to identify
and attack the seven wastes. As Toyota and other world-class
organizations have come to realize, customers will pay for value
added work, but never for waste.
About the Author
David McBride is co-founder of EMS Consulting Group, 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.
EMS Consulting Group helps companies implement lean strategies through lean training and lean consulting services. To learn more, read our lean manufacturing case studies or lean manufacturing articles.