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Lean manufacturing, lean enterprise, or lean
production, often simply, "Lean," is a production practice that considers the expenditure of resources for any goal
other than the creation of value for the end customer to be wasteful, and thus a target for elimination. Working
from the perspective of the customer who consumes a product or service, "value" is defined as any action or process
that a customer would be willing to pay for.
Essentially, lean is centred on preserving value
with less work. Lean manufacturing is a management philosophy derived mostly from the Toyota Production System
(TPS) (hence the term Toyotism is also prevalent) and identified as "Lean" only in the 1990s. TPS is renowned for
its focus on reduction of the original Toyota seven wastes to improve overall customer value, but there are varying
perspectives on how this is best achieved. The steady growth of Toyota, from a small company to the world's largest
automaker, has focused attention on how it has achieved this.
Lean manufacturing is a variation on the theme
of efficiency based on optimizing flow; it is a present-day instance of the recurring theme in human history toward
increasing efficiency, decreasing waste, and using empirical methods to decide what matters, rather than
uncritically accepting pre-existing ideas. As such, it is a chapter in the larger narrative that also includes such
ideas as the folk wisdom of thrift, time and motion study, Taylorism, the Efficiency Movement, and Fordism. Lean
manufacturing is often seen as a more refined version of earlier efficiency efforts, building upon the work of
earlier leaders such as Taylor or Ford, and learning from their mistakes. However, the modern view takes a more
holistic approach where the definition of waste is far more generic. Irregular production with ups and downs in
production levels would be considered waste. The goal of Lean then becomes the creation and maintenance of a
production system which runs repetitively, day after day, week after week in a manner identical to the previous
Both Lean and TPS can be seen as a loosely
connected set of potentially competing principles whose goal is cost reduction by the elimination of waste. These
principles include: Pull processing, Perfect first-time quality, Waste minimization, Continuous improvement,
Flexibility, Building and maintaining a long term relationship with suppliers, Automation, Load levelling and
Production flow and Visual control. The disconnected nature of some of these principles perhaps springs from the
fact that the TPS has grown pragmatically since 1948 as it responded to the problems it saw within its own
production facilities. Thus what one sees today is the result of a 'need' driven learning to improve where each
step has built on previous ideas and not something based upon a theoretical framework.
Toyota's view is that the main method of Lean is
not the tools, but the reduction of three types of waste: muda ("non-value-adding work"), muri ("overburden"), and
mura ("unevenness"), to expose problems systematically and to use the tools where the ideal cannot be achieved.
From this perspective, the tools are workarounds adapted to different situations, which explains any apparent
incoherence of the principles above.