It is only recently that the Lean principles have been applied to software development. In the beginning it all started with Lean manufacturing (some 40 to 60 years ago, depending on when you start the clock). Of course, it wasn’t called Lean back then. It was the Toyota Production System, or Just-In-Time manufacturing. James Womack, Daniel Jones, and Daniel Roos coined the term “Lean” in their 1990 book, The Machine That Changed the World (Harper Perennial).
Lean is a mindset, a way of thinking about how to deliver value to the customer more quickly by finding and eliminating waste (the impediments to quality and productivity). This philosophy is expressed in a set of principles that have proven remarkably applicable to a wide range of business activities. The Lean principles have been used successfully in areas as diverse as the supply chain, the office, engineering, and (of course) software development.
Lean is a mindset, a way of thinking about how to deliver value to the customer more quickly by finding and eliminating waste (the impediments to quality and productivity). This philosophy is expressed in a set of principles that have proven remarkably applicable to a wide range of business activities. The Lean principles have been used successfully in areas as diverse as the supply chain, the office, engineering, and (of course) software development.
A Whirlwind History of Lean
To really appreciate the emergence of Lean production and its derivatives, you have to
understand what it was replacing (or competing with): mass production.
Henry Ford popularized mass production (which had itself replaced craft production) with the
assembly-line manufacture of the Model T in 1913. Mass production is used to produce large
quantities of goods at a low unit cost. It divides the manufacturing process into small steps that can be carried out by unskilled workers, and it relies on the use of high-precision machinery and standardized, interchangeable parts.
The drawback of mass production is its inflexibility. Since a mass production assembly line is
so expensive to set up (and difficult to alter), it is only economical if it is going to produce large
quantities of the same thing.
In 1945, in post-war Japan, the president of Toyota Motor Company, Kiichiro Toyoda, said
that the Japanese automobile industry would not survive if it did not “catch up with America
in three years.” This did not happen within three years (the Japanese automobile industry
survived anyway), but it did lead to the creation of the Toyota Production System by Taiichi
Ohno.
Taiichi Ohno realized that the American mass production system would not work in Japan.
The domestic automobile market was too small and there was a significant demand for variety
understand what it was replacing (or competing with): mass production.
Henry Ford popularized mass production (which had itself replaced craft production) with the
assembly-line manufacture of the Model T in 1913. Mass production is used to produce large
quantities of goods at a low unit cost. It divides the manufacturing process into small steps that can be carried out by unskilled workers, and it relies on the use of high-precision machinery and standardized, interchangeable parts.
The drawback of mass production is its inflexibility. Since a mass production assembly line is
so expensive to set up (and difficult to alter), it is only economical if it is going to produce large
quantities of the same thing.
In 1945, in post-war Japan, the president of Toyota Motor Company, Kiichiro Toyoda, said
that the Japanese automobile industry would not survive if it did not “catch up with America
in three years.” This did not happen within three years (the Japanese automobile industry
survived anyway), but it did lead to the creation of the Toyota Production System by Taiichi
Ohno.
Taiichi Ohno realized that the American mass production system would not work in Japan.
The domestic automobile market was too small and there was a significant demand for variety
in automobiles, from small economical cars to larger, luxury cars—a poor fit for mass
production. Out of necessity, Taiichi Ohno experimented with many ideas and techniques that
eventually evolved into the Toyota Production System.
Taiichi Ohno described the Toyota Production System as “a system for the absolute elimination of waste.” He wasn’t kidding. By the early 1990s, Toyota was 60% more productive with 50% fewer defects than its non-Lean competitors. According to Ohno, this striking advantage rested on two pillars: Just-In-Time and autonomation.
Just-In-Time
In the 1950s, a Japanese delegation from Toyota visited American businesses to study their
methods. They visited Ford Motor Company, the industry leader, but they were not impressed.
They were particularly appalled by the large amounts of inventory and the unevenness of the
amount of work performed in different parts of the factory.
However, when they visited an American supermarket, they were impressed with the way in
which products were reordered and restocked only after customers purchased them. This pull system inspired Taiichi Ohno to create Just-In-Time, which strives to keep inventories at each manufacturing step as low as possible (preferably zero). It is about providing the right material, in the right amount, at the right time, and in the right place.
According to Ohno, inventory is waste that costs the company money. Even worse, inventory
hides problems in the production system. This includes problems such as inadequate capacity,
inflexible equipment, and unreliable equipment. A major contribution of a Just-In-Time
system is that it exposes the causes of inventory-keeping so that they can be addressed.
production. Out of necessity, Taiichi Ohno experimented with many ideas and techniques that
eventually evolved into the Toyota Production System.
Taiichi Ohno described the Toyota Production System as “a system for the absolute elimination of waste.” He wasn’t kidding. By the early 1990s, Toyota was 60% more productive with 50% fewer defects than its non-Lean competitors. According to Ohno, this striking advantage rested on two pillars: Just-In-Time and autonomation.
Just-In-Time
In the 1950s, a Japanese delegation from Toyota visited American businesses to study their
methods. They visited Ford Motor Company, the industry leader, but they were not impressed.
They were particularly appalled by the large amounts of inventory and the unevenness of the
amount of work performed in different parts of the factory.
However, when they visited an American supermarket, they were impressed with the way in
which products were reordered and restocked only after customers purchased them. This pull system inspired Taiichi Ohno to create Just-In-Time, which strives to keep inventories at each manufacturing step as low as possible (preferably zero). It is about providing the right material, in the right amount, at the right time, and in the right place.
According to Ohno, inventory is waste that costs the company money. Even worse, inventory
hides problems in the production system. This includes problems such as inadequate capacity,
inflexible equipment, and unreliable equipment. A major contribution of a Just-In-Time
system is that it exposes the causes of inventory-keeping so that they can be addressed.
Autonomation (Jidoka)
Autonomation is a combination of the words autonomous and automation. It describes
machines that automate a process but are also intelligent enough to know when something is
wrong and stop immediately. This kind of machine can run unattended (autonomously) while
providing workers with full confidence that it is operating flawlessly. It doesn’t have to be
monitored, and it needs human attention only when it stops.
When it detects an abnormal condition, the machine will stop itself and a worker will halt the
production line. This focuses everyone’s attention on finding the root cause of the problem
and fixing it so that it will not recur. In this way, autonomation prevents the production of
defective components that would otherwise disrupt the production line or result in more costly rework at a later stage.
Waste (Muda)
The overarching goal of Lean production (or any form of Lean) is to deliver value to the
customer more quickly, and the primary way to do this is to find and eliminate waste. On the
surface this may seem like a simple thing, but exactly what is and what is not waste isn’t always obvious. Shigeo Shingo, who codeveloped the Toyota Production System with Taiichi Ohno, identified seven kinds of waste
Autonomation is a combination of the words autonomous and automation. It describes
machines that automate a process but are also intelligent enough to know when something is
wrong and stop immediately. This kind of machine can run unattended (autonomously) while
providing workers with full confidence that it is operating flawlessly. It doesn’t have to be
monitored, and it needs human attention only when it stops.
When it detects an abnormal condition, the machine will stop itself and a worker will halt the
production line. This focuses everyone’s attention on finding the root cause of the problem
and fixing it so that it will not recur. In this way, autonomation prevents the production of
defective components that would otherwise disrupt the production line or result in more costly rework at a later stage.
Waste (Muda)
The overarching goal of Lean production (or any form of Lean) is to deliver value to the
customer more quickly, and the primary way to do this is to find and eliminate waste. On the
surface this may seem like a simple thing, but exactly what is and what is not waste isn’t always obvious. Shigeo Shingo, who codeveloped the Toyota Production System with Taiichi Ohno, identified seven kinds of waste
DOTWIMP: THE SEVEN DEADLY WASTES
Lean has some pretty strict views on waste. Shigeo Shingo identified seven types of waste that are easily remembered by using the acronym DOTWIMP:
Defects
This is perhaps the most obvious type of waste. Lean focuses on preventing defects instead of
the traditional “find and fix” mentality.
Overproduction
Producing more than is needed, or producing it before it is needed. It is often visible as the
storage of materials.
Transportation
The unnecessary movement of parts between processes. When you move material and parts
between factories, work cells, desks, or machines, no value is created.
Waiting
People or parts waiting for the next production step.
Inventory
All material, work-in-progress, and finished products that are not being processed. Inventory
beyond the bare minimum consumes productive floor space and delays the identification of
problems (if you’ve got plenty of spares, there’s no incentive to fix quality-related problems).
Motion
People or equipment moving or walking more than is needed to perform the processing.
Processing
Overprocessing beyond the standard required by the customer. This adds additional cost
without adding additional value.
Additional eighth waste: underutilization of people
This is often cited as an additional type of waste beyond the original seven, and it refers to the
underutilization of the worker’s creativity and resourcefulness.
Lean has some pretty strict views on waste. Shigeo Shingo identified seven types of waste that are easily remembered by using the acronym DOTWIMP:
Defects
This is perhaps the most obvious type of waste. Lean focuses on preventing defects instead of
the traditional “find and fix” mentality.
Overproduction
Producing more than is needed, or producing it before it is needed. It is often visible as the
storage of materials.
Transportation
The unnecessary movement of parts between processes. When you move material and parts
between factories, work cells, desks, or machines, no value is created.
Waiting
People or parts waiting for the next production step.
Inventory
All material, work-in-progress, and finished products that are not being processed. Inventory
beyond the bare minimum consumes productive floor space and delays the identification of
problems (if you’ve got plenty of spares, there’s no incentive to fix quality-related problems).
Motion
People or equipment moving or walking more than is needed to perform the processing.
Processing
Overprocessing beyond the standard required by the customer. This adds additional cost
without adding additional value.
Additional eighth waste: underutilization of people
This is often cited as an additional type of waste beyond the original seven, and it refers to the
underutilization of the worker’s creativity and resourcefulness.
A key Lean activity is to break down a process into a map of its individual steps and identify
which steps add value and which steps do not—the waste. This is known as a value stream
map. The goal, then, is to eliminate the waste (muda) and improve the value-added steps
(kaizen). The waste is further subdivided into two categories: non-value-added but necessary
(given the current state of the system), and pure waste. Pure waste is easy to deal with—it can be eliminated immediately.
which steps add value and which steps do not—the waste. This is known as a value stream
map. The goal, then, is to eliminate the waste (muda) and improve the value-added steps
(kaizen). The waste is further subdivided into two categories: non-value-added but necessary
(given the current state of the system), and pure waste. Pure waste is easy to deal with—it can be eliminated immediately.
So, there are two key Lean skills: knowing what the customer values, and knowing how to
spot waste.
spot waste.
Lean Principles
Taiichi Ohno started with Just-In-Time and autonomation, the two pillars of the Toyota
Production System. Modern-day Lean has settled on five principles and a wide array of
practices that have been distilled from the Toyota Production System and the experiences of
other companies that have followed Toyota’s lead. These five principles are identified as Value, Value Stream, Flow, Pull, and Perfection:
Value
Value is defined by the customer. What does the customer value in the product? You have
to understand what is and what is not value in the eye of the customer in order to map
the value stream.
Value stream
Once you know what the customer values in your product, you can create a value stream
map that identifies the series of steps required to produce the product. Each step is
Production System. Modern-day Lean has settled on five principles and a wide array of
practices that have been distilled from the Toyota Production System and the experiences of
other companies that have followed Toyota’s lead. These five principles are identified as Value, Value Stream, Flow, Pull, and Perfection:
Value
Value is defined by the customer. What does the customer value in the product? You have
to understand what is and what is not value in the eye of the customer in order to map
the value stream.
Value stream
Once you know what the customer values in your product, you can create a value stream
map that identifies the series of steps required to produce the product. Each step is
categorized as either value-added, non-value-added but necessary, or non-value-added
waste.
Flow
The production process must be designed to flow continuously. If the value chain stops
moving forward (for any reason), waste is occurring.
Pull
Let customer orders pull product (value). This pull cascades back through the value stream
and ensures that nothing is made before it is needed, thus eliminating most in-process
inventory.
Perfection
Strive for perfection by continually identifying and removing waste.
waste.
Flow
The production process must be designed to flow continuously. If the value chain stops
moving forward (for any reason), waste is occurring.
Pull
Let customer orders pull product (value). This pull cascades back through the value stream
and ensures that nothing is made before it is needed, thus eliminating most in-process
inventory.
Perfection
Strive for perfection by continually identifying and removing waste.
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