lean manufacturing or lean production operation management

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What is Lean Manufacturing?

Lean manufacturing 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 theend customer to be wasteful, and thus a target for elimination.

Lean manufacturing is a management philosophy derived mostly from the ToyotaProduction System (TPS) (hence the term Toyotism is also prevalent) and identified as

"Lean" only in the 1990s.[1][2] It is renowned for its focus on reduction of the original

Toyota seven wastes to improve overall customer value, but there are varying perspectiveson how this is best achieved. The steady growth of Toyota, from a small company to the

world's largest automaker,[3] has focused attention on how it has achieved this.

Lean manufacturing is a variation on the theme of efficiency based on optimizing flow; it isa 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 narrativethat 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 leaderssuch as Taylor or Ford, and learning from their mistakes.

History:

Lean principles come from the Japanesemanufacturing industry. The term was

first coined by John Krafcik in a Fall1988 article, "Triumph of the LeanProduction System," published in the

Sloan Management Review and based on

his master's thesis at the MIT SloanSchool of Management.[4] Krafcik had

been a quality engineer in the Toyota-GM

NUMMI joint venture in Californiabefore coming to MIT for MBA studies.

Krafcik's research was continued by the

International Motor Vehicle Program

(IMVP) at MIT, which produced theinternational best-seller book co-authored

by Jim Womack, Daniel Jones, and

Daniel Roos called The Machine ThatChanged the World.[1] A complete

historical account of the IMVP and how

the term "lean" was coined is given byHolweg (2007).[2] For many, Lean is the
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set of "tools" that assist in the identification and steady elimination of waste (muda). As

waste is eliminated quality improves while production time and cost are reduced. Examples

of such "tools" are Value Stream Mapping, Five S, Kanban (pull systems), andpoka-yoke(error-proofing).

Lean implementation is therefore focused on getting the right things to the right place at theright time in the right quantity to achieve perfect work flow, while minimizing waste and

being flexible and able to change. These concepts of flexibility and change are principallyrequired to allow production leveling, using tools like SMED, but have their analogues in

other processes such as research and development (R&D). The flexibility and ability to

change are within bounds and not open-ended, and therefore often not expensive capabilityrequirements. More importantly, all of these concepts have to be understood, appreciated,

and embraced by the actual employees who build the products and therefore own the

processes that deliver the value. The cultural and managerial aspects of Lean are possiblymore important than the actual tools or methodologies of production itself. There are many

examples of Lean tool implementation without sustained benefit, and these are often

blamed on weak understanding of Lean throughout the whole organization.

Lean aims to make the work simple enough to understand, do and manage. To achievethese three goals at once there is a belief held by some that Toyota's mentoring process,

(loosely calledSenpai andKohai), which is Japanese for senior and junior, is one of the

best ways to foster Lean Thinking up and down the organizational structure. This is theprocess undertaken by Toyota as it helps its suppliers improve their own production. The

closest equivalent to Toyota's mentoring process is the concept of "Lean Sensei," which

encourages companies, organizations, and teams to seek outside, third-party experts, who

can provide unbiased advice and coaching, (see Womack et al., Lean Thinking, 1998).

Steps to achieve lean systems

The following steps should be implemented to create the ideal lean manufacturing system:

1. Design a simple manufacturing system

2. Recognize that there is always room for improvement3. Continuously improve the lean manufacturing system design

Advantages of Lean Manufacturing

Time Savings
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Assume a worker on an assembly line must use two different sockets to do herjob. If it

takes the worker 10 seconds to change the sockets on the ratchet, then that 10 seconds

is wasted, because it was not spent actually making the product. If the worker mustchange the sockets hundreds of times per day, then that means she spends several

thousand seconds out of her day just changing sockets.

Quality Control

In the past, manufacturers had quality inspectors who inspected final products thatcame off the assembly lines. Lean has evolved from Total Quality Management and

seeks to build quality into the process.

Saves Money

The two aforementioned traits of lean manufacturing both lend to the money savingsthat lean helps to accomplish. But, lean as adapted to aculture as a whole creates an

environment that strives to eliminate all waste, whether it is waste in steps, material, orspending.

Saves Space

In the drive for eliminating waste, lean manufacturing is focused around workspace

layout. By organizing workspace and keeping the appropriate tools within reach, lean

manufacturing saves space. One example of lean manufacturing is "5S", which works

to separate tools and place each item in a "home" so that it is always easy to find.

Continuous Improvement

Lean manufacturers never rest on their accomplishments; rather they strive to

continually improve their process.

Disadvantages of Lean Manufacturing

Supply Problems

Because only a small amount of inventory is kept on hand, lean manufacturing depends

heavily on suppliers that can provide products for the manufacturing process
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dependably and without interruption. Problems like employee strikes, transportation

delays and quality errors on the part of suppliers can create manufacturing holdups that

can be fatal.

High Cost of Implementation

Implementing lean manufacturing often means completely dismantling previous

physical plant setups and systems.

Lack of Acceptance by Employees

Lean manufacturing processes require a complete overhaul of manufacturing systemsthat may cause stress and rejection by employees who prefer old ways of doing things.

Moreover, lean manufacturing requires constant employee input on quality control,

which some employees may feel disinclined or unqualified to do.

Customer Dissatisfaction Problems

Because lean manufacturing processes are so dependent on supplier efficiency, any

disruption in the supply chain--and therefore, on production--can be a problem that

adversely affects customers. Delivery delays can cause long-lasting marketingproblems that can be difficult to overcome.

ConclusionLean manufacturing and more generally lean enterprise work principles are widely taughtthroughout most industries now, and yet there are still companies that persistently refuse to

embrace the ideas. With the prevalence of lean ideas and books it is amazing to see that as

recently as 2005, polls among manufacturing managers showed that 41% of them admitted

to little understanding of what lean was. Another 34% were familiar with the term but didnot really know how to achieve it. 22% replied that their companies were on the lean


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path but not getting the desired results, and only 3% were undergoing lean transformations

with great results (Koenigsaecker 2005).

Bibliography:http://en.wikipedia.org/wiki/Lean_manufacturing

http://www.ehow.com/about_5418429_advantages-disadvantages-lean-production.html
http://en.wikipedia.org/wiki/Lean_manufacturinghttp://www.ehow.com/about_5418429_advantages-disadvantages-lean-production.htmlhttp://en.wikipedia.org/wiki/Lean_manufacturinghttp://www.ehow.com/about_5418429_advantages-disadvantages-lean-production.html

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