U.S. manufacturers have always searched for efficiency
strategies that help reduce costs, improve output, establish competitive
position, and increase market share. Early process oriented, mass production
manufacturing methods common before World War II shifted afterward to the
results-oriented, output-focused, production systems that control most of
today's manufacturing businesses.
Japanese manufacturers re-building after the Second World
War were facing declining human, material, and financial resources. The
problems they faced in manufacturing were vastly different from their Western
counterparts. These circumstances led to the development of new, lower cost,
manufacturing practices. Early Japanese leaders such as the Toyota Motor
Company's Eiji Toyoda, Taiichi Ohno, and Shingeo Shingo developed a
disciplined, process-focused production system now known as the "Toyota
Production System", or "lean production." The objective of this
system was to minimize the consumption of resources that added no value to a
product.
The "lean manufacturing" concept was popularized
in American factories in large part by the Massachusetts Institute of
Technology study of the movement from mass production toward production as
described in The Machine That Changed the World, (Womack, Jones and Roos,
1990), which discussed the significant performance gap between Western and
Japanese automotive industries. This book described the important elements
accounting for superior performance as lean production. The term
"lean" was used because Japanese business methods used less human
effort, capital investment, floor space, materials, and time in all aspects of
operations. The resulting competition among U.S. and Japanese automakers over
the last 25 years has lead to the adoption of these principles within all U.S.
manufacturing businesses.
WHAT IS LEAN
MANUFACTURING?
Lean Manufacturing can be defined as:
"A systematic
approach to identifying and eliminating waste (non-value-added activities)
through continuous improvement by flowing the product at the pull of the
customer in pursuit of perfection."
VALUE
In lean production, the value of a product is defined solely
by the customer. The product must meet the customer's needs at both a specific
time and price. The thousands of mundane and sophisticated things that
manufacturers do to deliver a product are generally of little interest to
customers. To view value from the eyes of the customer requires most companies
to undergo comprehensive analysis of all their business processes. Identifying
the value in lean production means to understand all the activities required to
produce a specific product, and then to optimize the whole process from the
view of the customer. This viewpoint is critically important because it helps
identify activities that clearly add value, activities that add no value but
cannot be avoided, and activities that add no value and can be avoided.
CONTINUOUS
IMPROVEMENT
The transition to a lean environment does not occur
overnight. A continuous improvement mentality is necessary to reach your
company's goals. The term "continuous improvement" means incremental
improvement of products, processes, or services over time, with the goal of
reducing waste to improve workplace functionality, customer service, or product
performance (Suzaki, 1987). Continuous improvement principles, as practiced by
the most devoted manufacturers, result in astonishing improvements in
performance that competitors find nearly impossible to achieve.
Lean production, applied correctly, results in the ability
of an organization to learn. As in any organization, mistakes will always be
made. However, mistakes are not usually repeated because this is a form of
waste that the lean production philosophy and its methods seek to eliminate.
CUSTOMER FOCUS
A lean manufacturing enterprise thinks more about its
customers than it does about running machines fast to absorb labor and
overhead. Ensuring customer input and feedback assures quality and customer
satisfaction, all of which support sales.
PERFECTION
The concept of perfection in lean production means that
there are endless opportunities for improving the utilization of all types of
assets. The systematic elimination of waste will reduce the costs of operating
the extended enterprise and fulfills customer's desire for maximum value at the
lowest price. While perfection may never be achieved, its pursuit is a goal
worth striving for because it helps maintain constant vigilance against
wasteful practices.
FOCUS ON WASTE
The aim of Lean Manufacturing is the elimination of waste in
every area of production including customer relations, product design, supplier
networks, and factory management. Its goal is to incorporate less human effort,
less inventory, less time to develop products, and less space to become highly
responsive to customer demand while producing top quality products in the most
efficient and economical manner possible.
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Essentially, a "waste" is anything that the
customer is not willing to pay for. Typically the types of waste considered in
a lean manufacturing system include:
Overproduction: to produce more than demanded or produce it
before it is needed. It is visible as storage of material. It is the result of
producing to speculative demand. Overproduction means making more than is
required by the next process, making earlier than is required by the next
process, or making faster than is required by the next process. Causes for
overproduction waste include:
Just-in-case logic.
Misuse of automation.
Long process setup.
Unlevel scheduling.
Unbalanced work load.
Over engineered.
Redundant
inspections.
Waiting: for a machine to process should be eliminated. The
principle is to maximize the utilization/efficiency of the worker instead of
maximizing the utilization of the machines. Causes of waiting waste include:
Unbalanced work load
Unplanned maintenance
Long process set-up
times
Misuses of automation
Upstream quality
problems
Unlevel scheduling
Inventory or Work in Process (WIP): is material between
operations due to large lot production or processes with long cycle times.
Causes of excess inventory include:
Protecting the
company from inefficiencies and unexpected problems
Product complexity
Unleveled scheduling
Poor market forecast
Unbalanced workload
Unreliable shipments
by suppliers
Misunderstood
communications
Reward systems
Processing waste: should be minimized by asking why a
specific processing step is needed and why a specific product is produced. All
unnecessary processing steps should be eliminated. Causes for processing waste
include:
Product changes
without process changes
Just-in-case logic
True customer
requirements undefined
Over processing to
accommodate downtime
Lack of
communications
Redundant approvals
Extra
copies/excessive information
Transportation: does not add any value to the product.
Instead of improving the transportation, it should be minimized or eliminated
(e.g. forming cells). Causes of transportation waste include:
Poor plant layout
Poor understanding of
the process flow for production
Large batch sizes,
long lead times, and large storage areas
Motion: of the workers, machines, and transport (e.g. due to
the inappropriate location of tools and parts) is waste. Instead of automating
wasted motion, the operation itself should be improved. Causes of motion waste
include:
Poor people/machine effectiveness
Inconsistent work
methods
Unfavorable facility
or cell layout
Poor workplace
organization and housekeeping
Extra
"busy" movements while waiting
Making defective products: is pure waste. Prevent the
occurrence of defects instead of finding and repairing defects. Causes of
processing waste include:
Weak process control
Poor quality
Unbalanced inventory
level
Deficient planned
maintenance
Inadequate
education/training/work instructions
Product design
Customer needs not
understood
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Underutilizing people: not taking advantage of people's
abilities. Causes of people waste include:
Old guard thinking,
politics, the business culture
Poor hiring practices
Low or no investment
in training
Low pay, high
turnover strategy
Nearly every waste in the production process can fit into at
least one of these categories. Those that understand the concept deeply view
waste as the singular enemy that greatly limits business performance and
threatens prosperity unless it is relentlessly eliminated over time. Lean
manufacturing is an approach that eliminates waste by reducing costs in the
overall production process, in operations within that process, and in the
utilization of production labor. The focus is on making the entire process
flow, not the improvement of one or more individual operations.