QMS, ISO and Six Sigma
Any Quality Management System must satisfy four requirements.
1. Processes must be defined and their procedures appropriately documented.
2. Processes are fully deployed and implemented as stated.
3. Processes are effective in providing the expected results.
4. An Improvement System must be in place to improve Processes.
ISO 9001 Standard
ISO 9001 is based on eight Quality Management Principles.
1. Focus on your customers
2. Provide leadership
3. Involve your people
4. Use a process approach
5. Take a systems approach
6. Encourage continual improvement
7. Get the facts before you decide
8. Work with your suppliers
Six Sigma is a Project Management Process
If a QMS system is in place, an organization may be confronted with a major challenge(s) which
crosses Organizational Boundaries. Six Sigma is an effective Project Management tool for
addressing such challenges. Six Sigma may be used in addressing a variety of such major
challenges. There are two situations, in particular, where Six Sigma has been shown to be
particularly effective:
1. A major Quality Issue whose resolution requires an effort which crosses organizational
boundaries.
2. New Product Development for complex products in rapidly evolving Market conditions.
What is a Sigma?
Determining sigma levels of processes (one sigma, six sigma, etc.) allows process performance
to be compared throughout an entire organization, because it is independent of the process. It
is merely a determination of opportunities and defects, however the terms are appropriately
defined for that specific process.
Sigma is a statistical term that measures how much a process varies from perfection, based on
the number of defects per million units.
One Sigma = 690,000 per million units
Two Sigma = 308,000 per million units
Three Sigma = 66,800 per million units
Four Sigma = 6,210 per million units
Five Sigma = 230 per million units
Six Sigma = 3.4 per million units
In formulae for control limits and process capabilities, sigma is the symbol for Standard
Deviation, calculated from the squares of the deviations of measured samples from the mean
value (or sometimes by other methods using 'magic' numbers). For a normally distributed
output, 99.7% would be expected to fall between +/-(3 x sigma) levels.
What is Six Sigma?
What does it mean to be "Six Sigma"? Six Sigma at many organizations simply means a measure
of quality that strives for near perfection. But the statistical implications of a Six Sigma program
go well beyond the qualitative eradication of customer-perceptible defects. It's a methodology
that is well rooted in mathematics and statistics.
The objective of Six Sigma Quality is to reduce process output variation so that on a long term
basis, which is the customer's aggregate experience with our process over time, this will result
in no more than 3.4 defect Parts Per Million (PPM) opportunities (or 3.4 Defects Per Million
Opportunities – DPMO). For a process with only one specification limit (Upper or Lower), this
results in six process standard deviations between the mean of the process and the customer's
specification limit (hence, 6 Sigma). For a process with two specification limits (Upper and
Lower), this translates to slightly more than six process standard deviations between the mean
and each specification limit such that the total defect rate corresponds to equivalent of six
process standard deviations.
Many processes are prone to being influenced by special and/or assignable causes that impact
the overall performance of the process relative to the customer's specification. That is, the
overall performance of our process as the customer views it might be 3.4 DPMO (corresponding
to Long Term performance of 4.5 Sigma). However, our process could indeed be capable of
producing a near perfect output (Short Term capability – also known as process entitlement –
of 6 Sigma). The difference between the "best" a process can be, measured by Short Term
process capability, and the customer's aggregate experience (Long Term capability) is known as
Shift depicted as Zshift or sshift. For a "typical" process, the value of shift is 1.5; therefore,
when one hears about "6 Sigma," inherent in that statement is that the short term capability of
the process is 6, the long term capability (Ppk here) is 4.5 (3.4 DPMO – what the customer sees)
with an assumed shift of 1.5. Typically, when reference is given using DPMO, it denotes the
Long Term capability of the process, which is the customer's experience. The role of the Six
Sigma professional is to quantify the process performance (Short Term and Long Term
capability) and based on the true process entitlement and process shift, establish the right
strategy to reach the established performance objective
As the process sigma value increases from zero to six, the variation of the process around the
mean value decreases. With a high enough value of process sigma, the process approaches zero
variation and is known as 'zero defects.'
D - Define Phase: Define the project goals and customer (internal and external)
deliverables.
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Define Customers and Requirements (CTQs)
Develop Problem Statement, Goals and Benefits
Identify Champion, Process Owner and Team
Define Resources
Develop Project Plan and Milestones
Develop High Level Process Map
M - Measure Phase: Measure the process to determine current performance;
quantify the problem.
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Define Defect, Opportunity, Unit and Metrics
Detailed Process Map of Appropriate Areas
Develop Data Collection Plan
Validate the Measurement System
Collect the Data
Determine Process Capability and Sigma Baseline
A - Analyze Phase: Analyze and determine the root cause(s) of the defects.
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Define Performance Objectives
Identify Value/Non-Value Added Process Steps
Identify Sources of Variation
Determine Root Cause(s)
I - Improve Phase: Improve the process by eliminating defects.
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Develop Potential Solutions
Define Operating Tolerances of Potential System
Assess Failure Modes of Potential Solutions
Validate Potential Improvement by Pilot Studies
Correct/Re-Evaluate Potential Solution
C - Control Phase: Control future process performance.
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Define and Validate Monitoring and Control System
Develop Standards and Procedures
Implement Statistical Process Control
Determine Process Capability
Develop Transfer Plan, Handoff to Process Owner
Verify Benefits, Cost Savings/Avoidance, Profit Growth
Close Project, Finalize Documentation
Communicate to Business