Understand
Six Sigma + Lean.
A compact introduction to the methodology that measurably improves processes — structured for self-directed learning, at your own pace.
The Parable of the Rowers
A simple story that illustrates a typical pattern in everyday business — and describes the trigger for structured problem solving.
A man stood by a lake watching two rowers in a boat. The boat was not moving and was sitting low in the water at one end. The rowers were bailing water with all their might, but water kept flowing in through a leak. The man called out to the rowers, telling them to come ashore and fix the boat — but they said that was impossible, because they were busy bailing water.
This same picture can exist in organisations!This parable illustrates a widespread problem: employees are often so busy dealing with symptoms that they never get around to fixing the actual root cause. The leak in the boat symbolises inefficient processes or recurring defects.
It is essential that organisations avoid falling into a mode of constant crisis management and instead implement long-term solutions. Six Sigma helps to analyse problems systematically and solve them sustainably — rather than wasting resources on temporary fixes.
Why Do Some Problems Keep Coming Back?
Four typical reasons why the same problems recur in everyday business.
Problems recur when organisations lack a structured approach to problem solving. Instead of analysing root causes, only quick fixes are sought — ones that help in the short term but do not sustainably eliminate the problem.
Often the problem lies in the organisational culture: decisions are made based on opinions or gut feeling rather than measurable facts. A sustainable improvement process requires systematic data collection and analysis — only then can solutions be found that prevent not only acute but also recurring problems.
What Does Effective Problem Solving Require?
Four fundamental principles that do not merely mask problems, but eliminate them permanently.
A systematic method like Six Sigma helps to improve processes and solve problems in the long term. Through fact-based decisions, training and a structured approach, organisations ensure that problems are sustainably eliminated.
It is essential not only to implement solutions, but also to establish an organisational culture based on continuous improvement. Training for employees at all levels ensures that Six Sigma does not remain merely a theoretical concept, but is actively lived.
One Answer Is Called Six Sigma + Lean
Two proven methods — one powerful combination.
Six Sigma and Lean are two proven methods for process improvement. Six Sigma focuses on reducing variability and defects, while Lean aims to eliminate waste and streamline processes.
While Lean makes processes more efficient, Six Sigma ensures they run stably and defect-free. Combining both approaches makes it possible not only to reduce costs, but also to increase quality and customer satisfaction.
Guiding Principles for Six Sigma + Lean Implementation
Three truths that ground every Six Sigma programme — and protect against false expectations.
To many, Six Sigma appears to be a brilliantly simple miracle cure for major improvements and savings that are relatively easy to achieve.
Die Grundgesetze der Natur gelten aber auch für Six Sigma: Es gibt einen Zusammenhang zwischen Aufwand und Ertrag. „Man bekommt nichts geschenkt!"
Six Sigma is not a miracle cure, but an efficient system whose application requires consistency, methodology and genuine root cause analysis.
Six Sigma is not a magic solution, but a structured system for process improvement. It requires consistent application, sound analysis and systematic root cause research. Organisations that use Six Sigma successfully understand: improvements require effort, but pay off in the long run.
The Success Story of General Electric
How Jack Welch turned Six Sigma into a strategic lever in the 1990s.
"Six Sigma will bring GE to a new quality level — in a fraction of the time it would have taken with our old methods."
"Six Sigma is one of the most important initiatives GE has ever undertaken — and will become part of our genetic leadership code."
"In 1999, more than two billion dollars were generated through Six Sigma …"
GE under Jack Welch was one of the first companies to implement Six Sigma on a large scale. The savings and quality improvements achieved demonstrated how effective Six Sigma can be. Many companies followed this example and achieved similar successes.
Six Sigma History
From Motorola in the 80s to worldwide adoption — a methodology in three waves.
Exemplary Users Worldwide
Six Sigma began in the 1980s at Motorola and was later further developed by companies such as General Electric. Today it is used in many industries worldwide to improve processes and reduce error rates — from classic manufacturing to banks and hospitals.
Lean History
The roots lie in the Toyota Production System — and go back further than one might think.
Lean Management has its roots in the Toyota Production System (TPS). It is about avoiding waste and designing efficient processes. The combination of Lean and Six Sigma enables organisations to significantly improve their performance.
Six Sigma (DMAIC), Lean and Design for Six Sigma
Three disciplines with clearly defined goals — which complement each other.
Design for Six Sigma
Develop products better and faster. Sources of defects are eliminated already in the concept phase.
Six Sigma Classic
Reduce variation and improve quality. Statistical tools at the centre.
Lean
Remove unnecessary steps and waste. Focus on speed and value stream.
DMAIC is the classic cycle for process improvement in Six Sigma. DfSS (Design for Six Sigma) goes one step further and focuses on developing new products and processes with optimal quality from the start.
Six Sigma + Lean — Application Areas
Three key areas where the methodology demonstrably works.
Development & Engineering
Design for Six Sigma: Shifting defect detection and correction to the earliest possible stages of the development process.
Operational Support
Improving process performance in supporting processes such as HR, finance, purchasing and marketing.
Production & Service
Peak performance with highest efficiency, stable processes, extremely low error rates and high customer orientation.
Six Sigma + Lean can be applied in various areas — in production, service and administrative processes. The goal is always the same: to improve process performance and minimise error rates.
What is Six Sigma + Lean?
First: what it is not. And then: the central idea in four steps.
Six Sigma+Lean is a disciplined process that focuses on the customer and the delivery and development of (near) perfect products and services.
- 01Measure process defects
- 02Systematically identify root causes
- 03Eliminate root causes
- 04Design a zero-defect process
Six Sigma+Lean is not a slogan or trend, but a proven, disciplined method for process improvement. The focus is on eliminating defects and developing near-perfect products and services.
Sigma (σ) is a statistical term that measures how much a process varies around "perfection". A process with a higher sigma level has a lower defect rate. Six Sigma means: only 3.4 defects per million opportunities.
The Two Six Sigma + Lean Dimensions
Successful projects stand on two legs — project management and quality techniques.
Project Management
- Teamwork
- Milestone concept
- Goal orientation
- Long-term focus
- Documentation
Quality Techniques
- Statistical analyses
- Process improvement & control tools
- Understanding customer requirements
- Waste reduction (LEAN)
How and Why Six Sigma + Lean Works
Two simple fundamental principles — that change everything.
"Understand customer wishes in detail, fully meet customer requirements and consistently exceed customer expectations."
Only by understanding cause-and-effect relationships can process problems be consistently and sustainably resolved.
Customer orientation and root cause elimination are the two central principles. Processes are designed to remain permanently stable and to meet customer requirements as effectively as possible.
The "Critical to …" Approach
How vague customer wishes become measurable requirements — the translation process from VoC to measurable specifications.
The "Critical to …" approach ensures that all relevant aspects of a product or process are optimised. These can be Quality (CTQ), Cost (CTC) or Delivery (CTD). A general customer wish is translated via the CTx categories into a concrete, measurable specification — the Key-CTQ.
Six Sigma + Lean reduces Process Variation
The mathematical core: What does 6σ actually mean — and how many defects does that allow?
| Application Example | 4σ — Industry Standard (~1 % scrap) | 6σ — World Class (0.00034 %) |
|---|---|---|
| Mix-ups at births in Germany | 125 per week | 9 in 4 years |
| Too long/short landings at Frankfurt | 13 per day | 3 in 2 years |
| Erroneous operations | 1.350 per week | 1 in 20 years |
Target: maximum 3.4 defects per million opportunities
Six Sigma improves process performance to such an extent that defects are virtually eliminated. A 6-sigma process is extremely robust — it has a process capability index of cpk = 2.0 (short-term) or cpk = 1.5 (long-term, with typical ±1.5σ drift).
The Six Sigma + Lean Project Management Approach
DMAIC — five phases, one cycle. The backbone of every Six Sigma project.
Define: Clear definition of the problem and the objective.
Measure: The existing process is thoroughly investigated and recorded with data.
Analyse: Causes of the existing problem are identified. (Remember: no cause → no problem.)
Improve: Solutions are developed, evaluated, verified and implemented. Additional costs may arise here.
Control: Ensuring the sustainability of improvements through appropriate anchoring.
DMAIC stands for Define, Measure, Analyze, Improve, Control. This standardised cycle helps to systematically improve processes and ensure that improvements are maintained in the long term. With appropriate project selection, the standardised approach maximises the chances of success in all project dimensions — quality, cost and duration.
Tools of the DMAIC Cycle
Each phase uses its own tools. An overview — which you will deepen as a Yellow or Green Belt.
- Project Charter
- Gantt Chart
- SIPOC
- VoC → CTx-Tree
- Stakeholder analysis
- Team building
- Process model
- QFDeasy
- MSA / R&R
- cp, cpk, Sigma-Level
- Histogramm, Boxplot
- DPMO / ppm, Yield
- FMEA
- Pareto
- Ishikawa
- Hypothesis tests
- ANOVA, Korrelation
- Value stream analysis
- Design of Experiment
- Mind Map, 6-3-5
- Synektik
- Value stream design
- Decision matrix
- PDCA-Pilotierung
- SPC
- OCAP
- Training & audit plan
- Process standards
- Lessons Learned
- Project handbook
Each phase of the DMAIC cycle uses specific tools — e.g. SIPOC for process mapping, FMEA for risk analysis or SPC (Statistical Process Control) for process control. As a White Belt you do not need to master these tools, but merely know and classify them — deeper application takes place at Yellow and Green Belt level.
DMAIC in Practice — a Sample Project
Using a real example from solar cell manufacturing: What really happens in each phase?
Cell breakage (solar cells) at the metallisation lines is higher than guaranteed by the machine manufacturers and leads to significant financial loss. Line xxx1 previous quarter: 4.15% breakage
- Understand breakage causes
- Identify improvement potentials
- Reduce breakage to 2.0 %
The SIPOC model sketches the process on one page — from supplier to customer. This way everyone in the team knows what is being discussed.
Process Detail
Flowchart of all process steps from wafer printing to transport.
Parameter Model
Input, control and output parameters are systematically recorded.
Prioritisation
Data priority matrix evaluates variables by influence.
Statistical Detail
Histograms, time series — distribution and trend become visible.
ANOVA & Significance Test
Which factors actually have a statistically significant influence?
Ishikawa & Regression
Structured root cause search and correlation analyses.
DoE (Design of Experiment)
Interaction diagrams show effect combinations.
- → Technical measures from FMEA, statistics, DoE
- → Organisational measures (employee awareness, Poka Yoke)
- → Improvement of data collection
- → Recommendations outside the process chain
Measures are prioritised via pairwise parameter comparison: by quality improvement, cost, implementation duration and multiplier effect. The selected solutions are anchored in an implementation plan.
Each measure is evaluated against weighted criteria — the ranking follows objectively from the total and not from gut feeling.
SPC Installation
Statistical Process Control — control charts monitor the process continuously.
OCAP
Out-of-Control-Action-Plan: clear escalation levels for deviations.
Lessons Learned
Insights are documented and made available for other projects.
The cleaner the Define and Measure phases are completed, the faster and more valid the analysis. Experienced Black Belts say: "60% of project time belongs in the first two phases" — because only clean data and clear goals lead to robust results.
What Competencies Are Needed for Six Sigma + Lean?
The Belt concept organises knowledge and responsibility — inspired by Japanese martial arts.
Different Belts have different roles in Six Sigma projects. As a White Belt you receive a basic introduction — as a Black Belt you are an expert for complex projects. When you complete this training, you are ready to participate as a team member and can actively contribute to Six Sigma+Lean projects.
Lean and Six Sigma — One Method
Lean Six Sigma = Lean Sigma = Six Sigma + Lean. Formerly separate disciplines, today an integrated toolbox.
Elimination of waste, reduction of lead times, improvement of delivery reliability and cost reduction.
Using statistical techniques to understand and reduce process variation — primary goal: improve quality and reduce costs.
Lean reduces waste, Six Sigma reduces variability. Together they lead to optimal processes with high efficiency and quality. In modern programmes both methods are fully integrated — the toolboxes complement each other along the DMAIC cycle.
The 7 Mudas + 1
Learning to see waste — the first step to eliminating it. Eight categories from the Toyota Production System.
Muda (Japanese for "waste") refers to all activities that create no value for the customer. The 7 classic types of waste — waiting times, motion, defective products, etc. — were extended by an eighth category: the unused potential of employees. Those who learn to see these eight categories will find countless starting points for improvement in their own work environment.
Glossary — the Most Important Terms
A compact reference for the terms you will encounter again and again in Six Sigma+Lean projects.