Lean manufacturing vs Six Sigma

Comparing Six Sigma and lean manufacturing

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If you’ve been keeping up with the Fiix blog lately, you’ve seen our latest post about the role of maintenance in a lean manufacturing strategy. But lean is far from the only business strategy out there. Today we’ll explore Six Sigma and the ways in which it’s both similar to and separate from lean manufacturing. So, what is the difference between lean and Six Sigma? Let’s find out.

What is Six Sigma?

We’ll start with a definition. According to asq.org, Six Sigma is “a method that provides organizations with tools to improve the capability of their business processes”. Whereas the goal of lean manufacturing is to eliminate waste in the production process, the purpose of Six Sigma is to eliminate defects or errors that occur both in production and non-production environments. The Six Sigma philosophy sees anything that doesn’t meet the customer’s expectations as a defect. A defect could refer to a literal production defect in the manufacturing process or any variation in a customer’s experience.

As you may remember, lean manufacturing defines seven different kinds of waste that can occur in the production process and aims to eliminate any and all forms of waste wherever possible. Six Sigma, in contrast, is focused on statistical analysis, and uses the DMAIC method to implement process improvement, which stands for Define, Measure, Analyze, Improve, and Control. Let’s take a look at each of these steps more closely:

Define: Put simply, this step involves defining what the actual process problem is, and what its effect is on the rest of the process in question.

Measure: Once the problem is defined, current data should be measured. This will give you a baseline from which to start your improvements.

Analyze: Once the relevant data has been collected, an analysis should be conducted to help get to the root of the problem.

Improve: This is the trial-and-error part of the Six Sigma process, which means it could take the longest to complete. In this stage, solutions should be introduced, tested, recorded, and tweaked as needed.

Control: The right improvements may have been made, but the Six Sigma process doesn’t stop there. Any ongoing process should continue to be evaluated and improved upon over time. This requires full employee engagement as well as support from upper management.

So what is “Lean Six Sigma”?

You may have noticed a common theme emerging when discussing lean manufacturing, Six Sigma, and maintenance in general: continuous improvement comes up time and again. Whether it’s total productive maintenance, lean manufacturing, or any other facet of maintenance and asset management, it’s important that maintenance teams pay attention to the data and continuously raise the bar for their chosen KPIs.

With that in mind, it makes sense that lean manufacturing and Six Sigma have converged in some instances. Organizations that use a Lean Six Sigma strategy see it as a “fact-based, data-driven philosophy of improvement that values defect prevention over defect detection”. This definition acknowledges the fact that there are aspects to both strategies that are beneficial in a manufacturing setting, and integrate well with a TPM strategy.

Where to begin?

Asq.org suggests that maintenance teams begin with a lean approach since it will reduce waste and help them to understand their value streams. If process problems persist after successfully implementing a lean strategy, Six Sigma statistical analysis can be introduced to approach remaining problems from a more technical standpoint. As always, employing a total productive maintenance strategy will support each of these strategies by ensuring everyone is involved.

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