Lean vs. Six Sigma

Many people today tout Lean Six Sigma as a common tool to drive process improvement across industries and functions.  You may think that the two are one in the same, but Lean methodology and Six Sigma are two distinct tools to achieve performance improvement smashed together under one banner: LSS.

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Six Sigma

Six Sigma is oriented towards identifying and removing causes of defects and minimizing process variability.  The six sigma name references 3.94 defects per million, which is six standard deviations between the mean and control limits. Conducting a Six Sigma improvement project involves collecting data on the process, inputs, and outputs.  The practitioner then statistically analyzes the process data to understand capability and improvement opportunities.
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This approach makes sense for a stable and repeatable process that serves customer needs and is not anticipated to change.  Six Sigma is not well suited for updating a process for changing customer demands or a technological disruption.

Lean Methodology

Lean is a method and tool set focused on creating or re-defining a process, so it’s more capable to respond to changing customer demand and to eliminate waste.  While executing a lean process design, the project leader will lead the team through process mapping analysis to define the future state and then compare this against the current state to identify and quantify areas of waste and barriers to change.  

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In lean, waste definition extends beyond the obvious material consumption or wait times and into reducing handling and touches, ahead of schedule production, and wasted effort such as re-work.  The lean framework will cause a critical look at the entire process and certainly question the time and effort tied up in quality control processes.

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In a manufacturing environment, the lean process is setup to accommodate the needs of the customer as reducing their waste is a logical focus and result of the lean project.  A lean process methodology grounded in serving the customer what they want and when they need it will win that customer for the long term.

Future Vision

As a first step, companies need to think of their desired outcome of the project.  Lean and Six Sigma are both means to performance improvement. However, they both lead to different types of results and continuous improvement mindsets.  Six Sigma will deliver the process improvement, and Lean will create a process toward satisfying the customer needs.

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With Industry 4.0, the real possibility of LSS methodology is here.  The automation of real time data acquisition and analytics to identify the appropriate process sequence, to schedule preventive maintenance, and to drive out bad lots of raw materials.  The Internet of Things is the piece that will truly allow the convergence of Six Sigma and lean into a unified tool for performance improvement.