What is Lean Six Sigma?

Lean Six Sigma (LSS) is a structured problem-solving approach for improving quality and productivity. Lean approaches focus on improving speed and flow in business processes, which leads to the outcome of reducing waste. Tools such as value stream mapping (VSM), flow diagrams, 8D, FMEA, and OPCP are typically used. Six Sigma methods seek to reduce variation and/or defects in either processes or products. In these cases, methods such as statistical process control, design of experiments, and “Design for X” are often employed. The target metric is typically “Six Sigma”, which represents no more than 3.4 defects for every million opportunities you have to generate a defect. This means that how you define a defect is pretty important!

But what about if you want to take an integrated approach to problem solving, where you think about how reducing waste, reducing variation, and reducing defects are all inter-related? It is in precisely these cases that Lean Six Sigma is so valuable. Pundits advocating Lean will rightly note that Six Sigma methods don’t reduce waste; Six Sigma enthusiasts will point out that Lean can’t help you remove defects or manage variation. But what if the special cause that’s confounding your process is also generating tons of waste? Makes sense to look at the problem holistically, which is what LSS helps you do.

Both Lean and Six Sigma help us identify forces that make our processes unnecessarily complex. It is by rooting out these causes that we achieve the primary goals of LSS: reducing waste, reducing variation, and reducing defects. Using a framework like DMAIC helps us pose the following questions:

  • What’s your quality goal? (Hint: choose the most important from the three above)
  • How do you define a defect? (Note: this often changes for each new LSS project)
  • What tools can you use to achieve that quality goal, given a broad selection of Lean and Six Sigma methods to choose from?

(Specific examples illustrating how to ask and interpret these questions using DMAIC will be presented in future articles, along with a description of how to use the Lean Six Sigma Quality Transformation Toolkit – LSSQTT – to execute your project.)

A successfully completed Lean Six Sigma project will generate a clear tangible value. This could include financial savings, savings in time and effort, reduced costs of materials, improved cash flow, cycle time reduction, or improved (measurable) customer satisfaction. Typically, a single Lean Six Sigma project will improve only one or two of these variables. Don’t try to improve all at once, which could get you bogged down in details. Iteration is the key!

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