| What is it? |
| "Six Sigma" measures the capability of a process to perform defect-free work. Six Sigma means a failure rate of 3.4 parts per million or 99.9997% perfect; however, the term in practice is used to denote more than simply counting defects. Six Sigma can now imply a whole culture of strategies, tools, and statistical methodologies to improve the bottom line of companies. In all, six sigma is a rigorous analytical process for anticipating and solving problems. It is essentially based on three underlying facts - a) you can manage what you measure, b) you can measure what you can define, and c) you can define what you understand. The objective of six sigma is to improve profits through variability and defect reduction, yield improvement, improved consumer satisfaction and best-in-class product / process performance. The principal concepts of Six Sigma are critical to quality (attributes that matter most to the customer), variation (what the customer sees and feels) and processes in control (giving a consistent product/process). |
| Why is it important? |
World-class companies typically operate at about four sigma or 99% perfection. To get to the six-sigma level mean cutting down on huge costs and thereby the wasted dollars. For example, if you are four sigma - you would be producing products at the rate of 6200 defectives for every million you produce vs. 3.4 defectives if you are at the six sigma level. Moreover, six sigma improvement projects typically return in excess of $150k to $250k per project with a Black Belt returning as much as $1 million to the bottom line each year.
The popularity of Six Sigma is growing. Companies such as Motorola (1987), Texas Instruments (1988), IBM (1990), Asea Brown Boveri (1993), Allied Signal/Kodak (1994), GE (1995), Whirlpool, PACCAR, Invensys, & Polaroid (1996/98), and many other companies worldwide have successfully implemented Six Sigma. Recently Ford, DuPont, Dow Chemical, Microsoft and American Express have started working on instituting Six Sigma processes.
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| When to use it? |
Bottom line drives management action. What is your Cost of (poor) Quality? First you need to determine that. Properly implemented, six sigma implementation can become a profit-center for the company. Jack Welch at GE claims that the returns on six sigma implementation amount to about $500 million as of 1998. Six sigma can be seen as being complementary to other initiatives such as ISO or QS 9000 (which is mainly procedural), Total Quality Management (which is mainly cultural) and Statistical Process Control (which is primarily statistical process monitoring).
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| How to use it? |
Six Sigma focuses on process quality. As such, it falls into the category of a process capability (Cp) technique. Traditionally, a process is considered capable if the natural spread, plus and minus three sigma (a yield of 99.73%), was less than the engineering tolerance. A later refinement considered the process location as well as its spread (Cpk) and tightened the minimum acceptable so that the process was at least four sigma from the nearest engineering requirement. Six Sigma requires that processes operate such that the nearest engineering requirement is at least plus or minus six sigma from the process mean. This requires considerable scientific and testing actions - often thousands of tests are run on multiple variables to get an understanding of what's going on. Once you determine the process variables and using the other process analysis techniques, you need to consider the ones causing the major losses and work on making them more capable.
| 1. |
Understand who your consumers are and what your product / service is. Identify the value you are providing your consumers. |
| 2. |
Review consumer surveys, concession reports, and other data. Determine the standard for your product or service offering. |
| 3. |
Screen and prioritize issues by severity, frequency/likelihood of occurrence, etc. Put in place proper metrics. |
| 4. |
Determine the internal processes causing the most pain. Pinpoint variation to the standard and the metrics in place. |
| 5. |
Find out why and where the defects are occurring. Do a root cause analysis. |
| 6. |
Devise ways to address these defects effectively. Validate the new process. |
| 7. |
Setup a good metrics (six-sigma places a lot of emphasis on measurement). Follow-up on actions and ensure that these become the new standard operating process. |
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What or who is a Green Belt
- a person trained in the six sigma methodology who is a team member of six sigma process improvement action teams. |
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What is a Black Belt
a person who is part of the leadership structure for process improvement teams are called "Black Belts" (just as Total Quality utilized "Quality Improvement Team Leaders" to provide structure). Black Belts are highly-regarded, technically-oriented product or line personnel who have an ability to lead teams as well as to advise management.
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What is a Master Black Belt
a person trained in the six sigma methodology who acts as the organization-wide Six Sigmadirector or a program manager. He oversees Black Belts and process improvement projects and provides guidance to Black Belts as required. A Master Blackbelt teaches other six sigma students and helps them achieve Greenbelt and Blackbelt status. |
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Who drives Six Sigma?
Usually a top executive or senior manager who "talks the talk" and "walks the walk" of six sigma. This person is the sponsor, a catalyst and the driving force behind the organization's six sigma implementation. |
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What are the steps in
Six Sigma?
Six Sigma usually follows the steps of Define, Measure, Analyze, Implement and Control (DMAIC). Each step utilizes specific tools: |
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a) Define - project charter, pareto analysis, process map, value stream map, affinity diagram and fmea
b) Measure - prioritization matrix, capability analysis, measurement system analysis and basic data analysis tools - histograms, box plots, pareto analysis;
c) Analyze - failure modes and effects analysis, fish bone diagram, 8D, hypothesis testing, anova and regression analysis, design of experiments and response surface methodology;
d) Improve - process simulation, brainstorming, error-proofing;
e) Control - standard operating procedures, control charts for critical x's, before/after run charts and mistake proofing, 5s, failure modes and effects analysis. |
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| Food for Thought ! |
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