The lean manufacturing system originated in Toyota Motor Corporation’s vehicle production system (TPS). TPS is a specific way of making things, and it has since become well-known and studied worldwide. Two of the basic principles of TPS are:
- Jidoka (loosely translated as “automation with a human touch”) In the case of a problem, equipment immediately stops, preventing the production of defective products.
- Just-in-Time (JIT) In a continuous flow, each step of the process produces exactly what is needed for the next one.
Based on these two philosophies, TPS can produce high-quality vehicles that meet the requirements of every customer, one at a time, every time.
To understand the differences between Lean and Six Sigma, you need to redefine “Quality” in terms of value rather than defects. Similar to Lean, the process of achieving Six Sigma quality involves searching for ways to reduce Muda (a Japanese word meaning “waste”). It is worth noting that Six Sigma is implemented based on proven quality principles and techniques. It is a way of working toward practically error-free business performance that relies on methods that have been around for decades. Specifically, companies with Six Sigma implementation have taken a handful of proven methods to train a small team of in-house technical leaders, known as Six Sigma Black Belts, to a high level of proficiency in the application of these techniques.
While the methods Black Belts use might include highly-advanced computer technology, most of the tools are applied within a simple performance improvement model known as Define-Measure-Analyze-Improve-Control (DMAIC). This means that you can implement these techniques without the need for Black Belt skills.
A reminder that Six Sigma disciplines will help you with Lean, and help you continue to improve. Likewise, if you discover Lean is not working due to excessive variability of unknown problems, you can use Six Sigma to identify and address the root causes of those issues. There is no need to choose between Six Sigma and Lean—the solution is Lean Six Sigma.
Similarities Between Lean and Six Sigma
Six Sigma is a general approach for reducing Muda in any environment. It involves the collection of simple and sophisticated methods for analyzing complex cause-and-effect relationships, with the aim of discovering opportunities for improvement.
Lean offers a proven, pre-packaged set of solutions for Muda. Six Sigma can apply to the problems Lean addresses, yet it also strives to identify and solve other problems. There is a great deal of overlap between the two disciplines; however, they approach their common purpose from slightly different angles:
- Lean concentrates on waste reduction, whereas Six Sigma highlights variation reduction.
- Lean reaches its goals by using fewer technical tools such as kaizen, workplace organization, and visual controls, whereas Six Sigma generally uses statistical data analysis, experimental design, and hypothesis testing.
Ultimately, the two approaches are complementary. Here are some examples of the synergy between the two:
| Lean |
Six Sigma |
| Establishment of methodology for improvement |
Policy deployment methodology |
| Focus on customer value stream |
Customer requirements measurement, cross-functional management |
| Project-based implementation |
Project management skills |
| Understanding of current conditions |
Knowledge discovery |
| Product and production data collection |
Data collection and analysis tools |
| Current layout and flow documentation |
Process mapping and flowcharting |
| Process timing |
Data collection tools and techniques, SPC |
| Process capacity and Takt time calculations |
Data collection tools and techniques, SPC |
| Creation of standard work combination sheets |
Process control planning |
| Evaluation of all options |
Cause-and-effect, FMEA |
| New layout planning |
Team skills, project management |
| Testing to confirm improvement |
Statistical methods for a valid comparison, SPC |
| Reduction of cycle times, product defects, change over time, equipment failures, etc. |
7M tools, 7 QC tools, DOE |
Integrating Lean and Six Sigma into Lean Six Sigma
Even though Lean and Six Sigma have historically been taught as separate disciplines, a blend of these approaches known as Lean Six Sigma gives organizations the best shot at applying the right mindset, tactics, and tools to solve problems. Lean Six Sigma is based on a systematic approach and a combined toolkit to help your organization build its problem-solving muscles in a problem-solving culture. This means that, when you’re building new muscles, you’re also building new daily habits.
Benefits of Using Lean Six Sigma
Organizations face challenges on a daily basis, from rising costs to increasing waste. Implementing Lean Six Sigma techniques can provide a competitive advantage in the following methods:
Lean Six Sigma is a process improvement methodology that integrates the benefits of both Lean and Six Sigma techniques to help organizations streamline processes, reduce waste, and increase value. The disadvantages of these techniques are that they can be complex, and they often require a significant amount of training. However, you can achieve considerable benefits by using this strategy.
| Implements |
Benefits |
| Streamline processes |
Improved customer experience and increased loyalty |
| Develop more efficient process flows |
Higher bottom-line results |
| Switch from defect detection to defect prevention |
Reduced costs and waste |
| Decrease lead times |
Increased capacity and profitability |
| Standardize processes to promote organizational “nimbleness” |
Greater ability to pivot to everyday challenges |
| Engage employees in the effort |
Improved confidence and accelerated people development |
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