What is Lean Six Sigma?

Lean Six Sigma

What is Lean Six Sigma?

Lean Six Sigma is a process that aims to systematically eliminate waste and reduce variation.


Over the past few decades, streamlining processes has been identified as the key to unlocking the maximum efficiency of a plant. Particularly used in manufacturing industries, some studies have correlated being ‘lean’ with inventory management.

This correlation allowed studies to find out that since the 1980s, major manufacturing companies have shown an increasing trend in being lean. This reinforced the need to focus on improving processes, and continued the pursuit for applying Lean Six Sigma practices.

In the maintenance setting, the same concepts of being more efficient are definitely becoming more of a requirement than an option. The philosophy of continually improving processes by taking out redundant steps—while still consistently maintaining high standards—is being realized to drive the overall performance of a plant.

Lean Six Sigma combines two concepts that go together to increase effectiveness and efficiency: being Lean aims to eliminate waste while Six Sigma aims to reduce variations in processes.

The Lean method

It’s estimated that maintenance activities can make up 15 to 70% of the total cost of production of a factory. A huge impact on the total spend causes an equally huge motivation to remove any non-value-adding part.

Being lean focuses on identifying and eliminating unnecessary steps of a process. Various practices that promote a lean system have been developed to provide a guide for process improvements. Though most of these are historically developed for the manufacturing industries (e.g. 5S principle, Kaizen, Value-Stream Process, etc.), its application to maintenance procedures has started to pick up.

The key to lean maintenance is identifying the causes of waste proactively. Having a CMMS system that measures your biggest causes of waste is a good start for collecting insightful data. The time between failures of operation and the time it takes to repair equipment can be key areas to investigate. Moreover, proactive approaches to maintenance such as PM and PdM are shown to reduce unplanned downtime.

The Six Sigma method

The Six Sigma method is a framework to ensure that processes are created to consistently provide high quality output.

The five main phases of amethod is simplified as DMAIC:

  1. Define the problems you want to address and the objectives you want to achieve. This process involves the identification of resources, benefits, and timelines.
  2. Measure your baseline metrics as a comparison for future progress. Agree on the methods to collect data accurately and consistently.
  3. Analyze your data to identify root causes. It is important to establish cause-and-effect relationships between incidents and root causes to get to the source of the problem.
  4. Improve the process by implementing solutions to the identified problems. This phase may include testing and prototyping to ensure that the root causes are identified accurately.
  5. Control systems must be put in place to monitor the progress and effectiveness of implemented solutions.

The eight kinds of waste

At the end of the day, Lean Six Sigma aims to remove useless steps to your processes and to provide consistent quality of service across tasks. This is a constant process that needs continuous effort. Keeping an eye on the eight main kinds of waste—easily remembered as DOWNTIME—can keep you in check on how lean the plant is running.

  • Defects – errors and any output with poor quality
  • Overproduction – producing more than the required amount
  • Waiting – any unplanned downtime or idle time
  • Non-utilized talent – any indications of overstaffing or unused workforce
  • Transportation – unnecessary distances traveled from one location to another
  • Inventory – inefficient storage management
  • Motion – unnecessary movement of people or equipment
  • Extra processing – various processes that have no added value


Though the philosophy behind Lean Six Sigma was developed for the manufacturing industries, its applications to maintenance is more relevant than ever. Maintenance activities are essential to a plant’s overall performance and Lean Six Sigma offers methods to perform maintenance activities with consistently high standards while reducing unnecessary costs.

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