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Six Sigma vs Lean: A Comprehensive Comparison of Two Process Improvement Methodologies
By AMREP | Posted on February 02, 2024
Six Sigma and Lean are two commonly used methods for improving manufacturing operational excellence. While both are process improvement methods, they have slightly different focus areas. Six Sigma in manufacturing aims to reduce variation to the point where defects are counted in the parts per million. Lean is more systems oriented - it looks at creating a production system that focuses on reducing waste, creating customer value, and creating continuous process improvement.
- What Is Six Sigma?
- What Is Lean?
- Comparison of Six Sigma and Lean
- Explore Our Manufacturing Excellence Solutions!
What Is Six Sigma?
Six Sigma is critical for quality and precision in manufacturing. Originating in the 1980s at Motorola, it was a response to compete against Japanese manufacturing quality. The core of Six Sigma lies in its name and is derived from a statistical term signifying a near-perfect process with only 3.4 defects per million opportunities.
The DMAIC Methodology
The heart of Six Sigma is its 5 phases, DMAIC: Define, Measure, Analyze, Improve, and Control. Here’s what they mean -
- Define: Define the problem, improvement activity, opportunity for improvement, the project goals, and customer (internal and external) requirements.
- Measure: Measure process performance using process maps, capability analysis, and pareto charts.
- Analyse: Analyse the process using Root Cause Analysis, Failure Mode and Effects Analysis (FMEA), and Multi-vari charts, to eliminate root causes of variation and poor performance.
- Improve: Improve process performance with tools such as Design of Experiments (DOE) and Kaizen events to address and eliminate root causes.
- Control: Control the improved process and future process performance using tools like control plans, statistical process control, 5S, and poka-yokes.
Using Six Sigma to Control Defects and Eliminate Variation
As stated previously, Six Sigma is focused on eliminating variation. Variability in manufacturing can create manufacturing process problems which in turn leads to defects and production inconsistencies. The DMAIC methodology achieves variation elimination because it gets the manufacturer to scientifically and systematically do the following:
- Clearly understand how products are being produced and identify inefficiencies before working out the improvement steps.
- Develop a plan to understand the nature of the problem and how to address it.
- Implement the plan to cut waste to optimise value and achieve consistency in manufacturing processes by reducing the amount of variation that occurs.
- Collaboratively working with all stakeholders to identify variations that could have been missed.
When properly deployed, Six Sigma can achieve reduced scrap, shorter cycle times, improved on-time delivery, reduced operating costs, and greater customer satisfaction.
Six Sigma is used widely across all manufacturing industries. Incidentally, it has also become a general business process improvement tool and is used in non-manufacturing industries as well.
What Is Lean?
Lean originated from the Toyota Production System in Japan post World War II. It's an approach targeted at maximizing value through eliminating waste in manufacturing operations.
Principles of Lean Manufacturing
Lean's basis is built on numerous key principles:
- Identifying and Eliminating Waste (Muda): Lean identifies seven kinds of waste – defects, overproduction, ready, non-applied skills, transportation, stock, movement, and further processing – and seeks to put off them.
- Creating Value-Added Processes: Process activities should result in a product or service that the customer is willing to pay for. That is the meaning of value. Otherwise, this is considered as waste.
- Continuous Improvement (Kaizen): Lean encourages constant, incremental changes to enhance efficiency and excellence.
- Respect for People: Lean emphasizes appreciation for every person who contributes to the organisation and recognises that their insights are important for improvement.
- Involving All Levels of the Organization: Lean engages everybody, from the CEO to the manufacturing production workers, to pursue the highest production performance with maximum waste reduction.
Lean Tools and Techniques
To put into effect those principles, Lean makes use of several analytics tools:
- Value Stream Mapping (VSM): Value stream maps are similar to flowcharts but include additional information about various activities that occur at each step of the process. It is used to identify improvement opportunities and track performance.
- Kanban: A visual method for managing production workflows.
- Poka-Yoke (Mistake-Proofing): A process analysis tool used to make it impossible for errors to occur or to make the error immediately obvious once it has occurred.
Benefits of Lean in Manufacturing
When properly executed, Lean can result in greater manufacturing and business efficiencies.
Also, read about VDA 6.3 Process Audit
Comparison of Six Sigma and Lean
Here is a fuller comparison of Six Sigma and Lean.
- Focus: Six Sigma is geared closer to lowering defects and minimizing variability in production. Its intention is precision and defects reduction. Lean, however, centres on getting rid of waste (muda) and streamlining procedures. It specializes on systems performance and process flows.
- Approach: Six Sigma relies heavily on statistical evaluation to identify and resolve troubles. Lean has a broader focus and looks at the organisation’s overall functioning.
- Applications: Both have been adapted widely to manufacturing and non-manufacturing industries.
Read about 5 Phases Of Six Sigma in detail.
Integrating Six Sigma and Lean: Lean Six Sigma
During the 2000s, Lean and Six Sigma were integrated together to become a separate process improvement tool. This hybrid technique leverages Six Sigma’s statistics-driven defect elimination methods and Lean’s efficiency and waste reduction techniques. It results in a holistic and factual approach to improving performance by removing operational waste and preventing defect.
|Lean Six Sigma
|Reducing defects and variability
|Combining defect reduction with waste elimination
|Data-driven, statistical analysis
|People-focused, respect for employees
|Data-driven and people-focused
|Process improvement through precision
|Process simplification and efficiency
|Comprehensive process improvement
|Manufacturing (adaptable to other sectors)
|Various industries including services and healthcare
|Broad application across all sectors
|Kanban, Poka-yoke, VSM
|Blend of Six Sigma and Lean tools
Explore Our Manufacturing Excellence Solutions!
Six Sigma and Lean are effective methodologies, each with particular strengths – Six Sigma's precise approach for decreasing defects and Lean's method for reducing waste. By integrating these strategies, Lean Six Sigma emerges as an ideal solution for improving manufacturing performance and reducing costs. This is particularly essential for businesses who are operating in increasingly complex business environments with rising cost pressures.
For companies with externalised production operations and vendor partners, it can be advantageous to deploy supplier development or manufacturing specialists from companies like AMREP at the production or vendor sites. They use their extensive experience in developing Lean Six Sigma initiatives for many manufacturing outfits to work on-site and improve production at your vendor sites. This results in lower costs and better production outcomes for all parties. To learn more, please don’t hesitate to contact us!
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