Transcript The Scope and Language of Operations Management

Chapter 10
Principles of
Six Sigma
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Key Idea
Although we view quality improvement tools and
techniques from the perspective of Six Sigma, it
is important to understand that they are simply a
collection of methods that have been used
successfully in all types of quality management
and improvement initiatives, from generic TQM
efforts, to ISO 9000, and in Baldrige processes.
Six-Sigma Metrics
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Defect – any mistake or error that is
passed on to a customer
Defects per unit (DPU) = number of
defects discovered  number of units
produced
Defects per million opportunities
(dpmo) = DPU  1,000,000 
opportunities for error
Six-Sigma Quality
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Ensuring that process variation is half the
design tolerance (Cp = 2.0) while allowing
the mean to shift as much as 1.5 standard
deviations, resulting in at most 3.4 dpmo.
Key Idea
Although originally developed for manufacturing
in the context of tolerance-based specifications,
the Six Sigma concept has been operationalized
to any process and has come to signify a generic
quality level of at most 3.4 defects per million
opportunities.
k-Sigma Quality Levels
Problem Solving
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Problem: any deviation between what
“should be” and what “is” that is important
enough to need correcting
– Structured
– Semistructured
– Ill-structured
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Problem Solving: the activity associated
with changing the state of what “is” to what
“should be”
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Quality Problem Types
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2.
3.
4.
5.
Conformance problems
Unstructured performance problems
Efficiency problems
Product design problems
Process design problems
Key Factors in Six Sigma
Project Selection
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Financial return, as measured by costs
associated with quality and process
performance, and impacts on revenues and
market share
Impacts on customers and organizational
effectiveness
Probability of success
Impact on employees
Fit to strategy and competitive advantage
Problem Solving Process
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2.
3.
4.
Redefining and analyzing the
problem
Generating ideas
Evaluating and selecting ideas
Implementing ideas
Key Idea
A structured problem-solving process provides
all employees with a common language and a
set of tools to communicate with each other,
particularly as members of cross-functional
teams.
DMAIC Methodology
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3.
4.
5.
Define
Measure
Analyze
Improve
Control
Define
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Describe the problem in operational
terms
Drill down to a specific problem
statement (project scoping)
Identify customers and CTQs,
performance metrics, and
cost/revenue implications
Measure
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Key data collection questions
– What questions are we trying to answer?
– What type of data will we need to answer
the question?
– Where can we find the data?
– Who can provide the data?
– How can we collect the data with
minimum effort and with minimum
chance of error?
Analyze
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Focus on why defects, errors, or
excessive variation occur
Seek the root cause
5-Why technique
Experimentation and verification
Improve
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Idea generation
Brainstorming
Evaluation and selection
Implementation planning
Control
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Maintain improvements
Standard operating procedures
Training
Checklist or reviews
Statistical process control charts
Tools for Six-Sigma and
Quality Improvement
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Elementary statistics
Advanced statistics
Product design and reliability
Measurement
Process control
Process improvement
Implementation and teamwork
Design for Six Sigma
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Focus on optimizing product and process
performance
Features
– A high-level architectural view of the design
– Use of CTQs with well-defined technical requirements
– Application of statistical modeling and simulation
approaches
– Predicting defects, avoiding defects, and performance
prediction using analysis methods
– Examining the full range of product performance using
variation analysis of subsystems and components
Key Idea
All Six Sigma projects have three key
characteristics: a problem to be solved, a
process in which the problem exists, and one
or more measures that quantify the gap to be
closed and can be used to monitor progress.
Key Six Sigma Metrics in
Services
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Accuracy
Cycle time
Cost
Customer satisfaction
Lean Production and Six
Sigma
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The 5S’s: seiri (sort), seiton (set in order),
seiso (shine), seiketsu (standardize), and
shitsuke (sustain).
Visual controls
Efficient layout and standardized work
Pull production
Single minute exchange of dies (SMED)
Total productive maintenance
Source inspection
Continuous improvement
Traditional Economic Model
of Quality of Conformance
Total cost
Cost due to
nonconformance
“optimal level” of quality
Cost of
quality
assurance
100%
Modern Economic Model of
Quality of Conformance
Total cost
Cost due to
nonconformance
Cost of
quality
assurance
100%