Closing Comment: Six Sigma vs. Lean Manufacturing

July 26, 2006
Which is right for your company?

Six Sigma is nothing less than a phenomenon. From its origins at Motorola Inc. 20 years ago it has grown into a way of life in many organizations, many successful organizations that attribute their success to the Six Sigma approach.

For those unfamiliar, Six Sigma is a series of methods used to manage process variations that cause defects defined as unacceptable deviations from the mean (or target), and to work systematically to manage variation in order to eliminate those defects. The objectives of Six Sigma are to achieve “world-class” performance, reliability, and value for customers. Naturally, it has had a profound influence in manufacturing organizations, but it has also been adopted in service companies, financial institutions, and retailers.

While Six Sigma was originally defined as a metric for measuring defects in order to reduce their occurrence, thereby improve quality, it has grown well beyond defect control. It is an extremely powerful tool for achieving organizational improvement but, like any tool, it must be correctly applied. And, understanding how to apply Six Sigma methods properly and effectively is part of the mystique.

The breadth and detail of Six Sigma seems to offer room for an alternative approach for organizational improvement, and many manufacturing companies have found that alternative in Lean Manufacturing. It is not confined to applications in manufacturing, but that is the chief application that was pioneered and promoted by Toyota Corp.

Rather than seeking sources of defects, the Lean principals concentrate on reducing waste — of which seven types are identified: over-production, waiting time, transportation, processing, inventory, motion, and scrap. According to the Lean logic, by eliminating waste, quality and productivity are improved and cost is reduced. There are Lean “tools,” too, including constant process analysis, “pull” production, and mistake-proofing. As a management philosophy, Lean is focused on improving the workplace atmosphere, part of the effort to maintain an effective organization.

So much has been written and stated about these improvement processes — references, instructions, testimonials, competitive pressure — that a manufacturing organization may understandably ask: Six Sigma or Lean Manufacturing? Which one is right for you? Here are some key criteria to consider:

What is your objective? Do you have specific, difficult quality issues that must be resolved? Do you have a pressing need for general overall operating improvements? Or, are you just looking for an effective method to “force” improvement into your organization?

Look at your alternatives in this case: Six Sigma is a powerful tool, specifically designed to resolve complex quality problems. It is not, however, designed to address overall operating performance issues. Lean Manufacturing, on the other hand, is an all-encompassing philosophy that has been designed to address overall process improvement. Lean attempts to optimize an entire corporation. It is a comprehensive philosophy and process, with a portfolio of underlying techniques.

How soon do you need results? How urgent is your requirement? Are you launching an initiative that will be a gradual, illuminating, “nice to have” discovery process, or is there a pressing need for quick, substantial results?

Six Sigma is a process that rigorous, involving, and thorough. It entails a considerable amount of front-end training for your team before any meaningful work on improvement can begin. Lean Manufacturing, when correctly applied, has shown the ability to begin generating noteworthy results almost immediately.

Level of employee involvement? Are you looking to develop a small elite team of internal gurus? Or, are you looking for a process that involves the entire workforce in the continuous improvement process?

Due to its technical nature and the length of time required to become proficient, a Six Sigma initiative typically focuses resources on building expertise within a designated group of highly trained individuals (these are the people identified as “black belts”). Shop-floor operators are primarily bystanders in the change process.

Contrarily, a Lean transition involves the entire workforce, and generally results in the formation of “natural work teams.” It is in these work teams that process improvement ideas are identified and acted upon, often with minimal outside “expert” involvement. A significant portion of the innovation and implementation of Lean improvements are a direct result of the involvement of the general workforce.

Why not try both? Can a company or organization effectively make a transition to both Six Sigma and Lean Manufacturing simultaneously?

To transition to a Lean environment requires a huge commitment, and focus, from the top of the organization. Lean is, in most companies, initially a foreign philosophy. The transition typically requires a culture change and a substantial commitment. This is also true of a full-fledged Six Sigma implementation.

Attempting to do both, simultaneously, will almost always result in neither philosophy being done very well or effectively. In addition, the underlying philosophies can cause some conflict if attempted simultaneously. The classic Six Sigma implementation is a comprehensive re-evaluation that is examines elementary details in an exhaustive way with techniques that may seem rigid, as well as rigorous. By contrast, an effective transition to Lean has is reminiscent of Nike’s invocation, “Just Do It”: reduce the inventory and fix the problems that arise.

Which one to do first? If it doesn’t make sense to attempt to do both simultaneously, is there a reason why one method should be instituted before the other? And, if so, in what order?

Lean is an overall operating philosophy that is conceived as a way to drive the waste out of the system The Lean process will expose all sorts of problems. In the Lean “tool kit” there are a host of techniques that are applied to resolve the problems as they are exposed. One such technique is Six Sigma. The Lean toolkit also contains other quality improvement techniques such as sequential inspection, failsafe, source inspection, etc.

So, if your organization or process is already operating Lean, and you are now facing isolated difficult quality and/or process control issues, then a Six Sigma implementation may very likely be an appropriate and beneficial effort. However, if your organization is still operating in a traditional mode, doing Lean first will almost always generate much more meaningful results, sooner.

Six Sigma is a powerful tool when applied to appropriate quality and process control issues. It is not, however, an overall enterprise-improvement methodology.

The Lean Manufacturing transition process can be used to generate cash and overall global process improvements. Six Sigma methods should be then utilized, where it is appropriate, to resolve specific process quality/reliability issues.

The Hands-On Group helps client companies understand and incorporate the principles and practices of Lean Manufacturing, organizational change, process improvement and human resource development. Contact Jack Harrison at 407-299-5245, or visit