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Transcript of Intro to Statistical Quality Control
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Introduction to Statistical QualityControl, 5th edition
Douglas C. Montgomery
Arizona State University
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Chapter 1 3Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 4Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Learning Objectives
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Chapter 1 5Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
1-1 Definitions and Meaning of Quality
1-1.1 The Eight Dimensions of Quality
1. Performance
2. Reliability
3. Durability
4. Serviceability
5. Aesthetics
6. Features
7. Perceived Quality
8. Conformance to Standards
Chapter 1 6Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
This is a traditional definition
Quality of designQuality of conformance
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Chapter 1 7Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
This is a modern definition of quality
Chapter 1 8Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
The Transmission Example
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Chapter 1 9Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
The transmission example illustrates the utility of this definition
An equivalent definition is that quality improvement is the
elimination of waste. This is useful in service or transactional
businesses.
Chapter 1 10Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
1-1.2 Terminology
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Chapter 1 11Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Terminology contd
Specifications
Lower specification limit Upper specification limit
Target or nominal values
Defective or nonconforming product
Defect or nonconformity
Not all products containing a defect are
necessarily defective
Chapter 1 12Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
1-2. History of Quality Improvement
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Chapter 1 13Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 14Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 15Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 16Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 17Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Statistical Methods
Statistical process control (SPC)
Control charts, plus other problem-solving tools
Useful in monitoring processes, reducing variabilitythrough elimination of assignable causes
On-line technique
Designed experiments (DOX)
Discovering the key factors that influence processperformance
Process optimization
Off-line technique
Acceptance Sampling
Chapter 1 18Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Walter A. Shewart (1891-1967)
Trained in engineering and physics
Long career at Bell Labs
Developed the first control chart
about 1924
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Chapter 1 19Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
A factorial experiment with three factors
Chapter 1 20Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 21Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Effective management of quality requires the
execution of three activities:1. Quality Planning
2. Quality Assurance
3. Quality Control and Improvement
Chapter 1 22Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 23Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 24Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 25Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
1-4.1 Quality Philosophies and
Management Strategies
W. Edwards Deming
Taught engineering, physics in the1920s, finished PhD in 1928
Met Walter Shewhart at WesternElectric
Long career in governmentstatistics, USDA, Bureau of theCensus
During WWII, he worked withUS defense contractors, deployingstatistical methods
Sent to Japan after WWII to workon the census
Chapter 1 26Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Deming
Deming was asked by JUSE to lecture onstatistical quality control to management
Japanese adopted many aspects of Demingsmanagement philosophy
Deming stressed continual never-endingimprovement
Deming lectured widely in North Americaduring the 1980s; he died 24 December 1993
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Chapter 1 27Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Demings 14 Points
1. Create constancy of purpose toward improvement
2. Adopt a new philosophy, recognize that we are in a time ofchange, a new economic age
3. Cease reliance on mass inspection to improve quality
4. End the practice of awarding business on the basis of pricealone
5. Improve constantly and forever the system of production andservice
6. Institute training
7. Improve leadership, recognize that the aim of supervision ishelp people and equipment to do a better job
8. Drive out fear
9. Break down barriers between departments
Chapter 1 28Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
14 Points contd
10. Eliminate slogans and targets for the workforce such as zerodefects
11. Eliminate work standards
12. Remove barriers that rob workers of the right to pride in the
quality of their work13. Institute a vigorous program of education and self-
improvement
14. Put everyone to work to accomplish the transformation
Note that the 14 points are about change
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Chapter 1 29Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Demings Deadly Diseases
1. Lack of constancy of purpose
2. Emphasis on short-term profits
3. Performance evaluation, merit rating, annual
reviews
4. Mobility of management
5. Running a company on visible figures alone
6. Excessive medical costs for employee health care
7. Excessive costs of warrantees
Chapter 1 30Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Joseph M. Juran
Born in Romania (1904),immigrated to the US
Worked at Western Electric,influenced by WalterShewhart
Emphasizes a more strategicand planning orientedapproach to quality thandoes Deming
Juran Institute is still anactive organization
promoting the Juranphilosophy and qualityimprovement practices
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Chapter 1 33Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Total Quality Management (TQM)
Started in the early 1980s, Deming/Juran
philosophy as the focal point Emphasis on widespread training, quality
awareness
Training often turned over to HR function
Not enough emphasis on quality control andimprovement tools, poor follow-through, noproject-by-project implementation strategy
TQM was largely unsuccessful
Chapter 1 34Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Total Quality Management (TQM)
TQM is just another program
Value engineering
Zero defects Quality is free
Recipe for Ineffectiveness and maybe Disaster
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Chapter 1 35Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Quality Systems and Standards
Chapter 1 36Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
The ISO certification process focuses heavily on quality
assurance, without sufficient weight given to quality planning and
quality control and improvement
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Chapter 1 37Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 38Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
The MBNQA process is a valuable assessment tool
See Table 1-3 for Performance Excellence Criteria and point
values
The Malcolm Baldrige National
Quality Award
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Chapter 1 39Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 40Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
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Chapter 1 41Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Six Sigma
Use of statistics & other analytical tools has grown
steadily for over 80 years Statistical quality control (origins in 1920, explosive
growth during WW II, 1950s)
Operations research (1940s)
FDA, EPA in the 1970s
TQM (Total Quality Management) movement in the 1980s
Reengineering of business processes (late 1980s)
Six-Sigma (origins at Motorola in 1987, expanded impact
during 1990s to present)
Chapter 1 42Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Focus of Six Sigma is on Process Improvement
with an Emphasis on Achieving Significant
Business Impact
A process is an organized sequence of activities that
produces an output that adds value to the organization
All work is performed in (interconnected) processes
Easy to see in some situations (manufacturing)
Harder in others
Any process can be improved
An organized approach to improvement is necessary
The process focus is essential to Six Sigma
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Chapter 1 43Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Chapter 1 44Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Why Quality Improvement is Important:
A Simple Example
A visit to a fast-food store: Hamburger (bun, meat, special sauce,
cheese, pickle, onion, lettuce, tomato), fries, and drink.
This product has 10 components - is 99% good okay?
10
4
12
{Single meal good} (0.99) 0.9044
Family of four, once a month: {All meals good} (0.9044) 0.6690
{All visits during the year good} (0.6690) 0.0080
P
P
P
= =
= =
= =
10 4
12
{single meal good} (0.999) 0.9900, {Monthly visit good} (0.99) 0.9607
{All visits in the year good} (0.9607) 0.6186
P P
P
= = = =
= =
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Chapter 1 45Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Six Sigma Focus
Initially in manufacturing
Commercial applications Banking
Finance
Public sector
Services
DFSS Design for Six Sigma Only so much improvement can be wrung out of an
existing system
New process design
New product design (engineering)
Chapter 1 46Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Some Commercial Applications
Reducing average and variation of days outstanding onaccounts receivable
Managing costs of consultants (public accountants, lawyers)
Skip tracing
Credit scoring Closing the books (faster, less variation)
Audit accuracy, account reconciliation
Forecasting
Inventory management
Tax filing
Payroll accuracy
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Chapter 1 47Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Six Sigma
A disciplined and analytical approach to process and productimprovement
Specialized roles for people; Champions, Master Black belts,Black Belts, Green Belts
Top-down driven (Champions from each business)
BBs and MBBs have responsibility (project definition,leadership, training/mentoring, team facilitation)
Involves a five-step process (DMAIC) : Define
Measure
Analyze
Improve
Control
Chapter 1 48Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
What Makes it Work?
Successful implementations characterized by:
Committed leadership
Use of top talent
Supporting infrastructure Formal project selection process
Formal project review process
Dedicated resources
Financial system integration
Project-by-project improvement strategy(borrowed from Juran)
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Chapter 1 49Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
OVERALL PROGRAMS
LEAN Variation Reduction
Predictability
Feasibility
Efficiency
Capability
Accuracy
Flow Mapping
Waste Elimination
Cycle Time
WIP Reduction
Operations and
Design
Lean
Lead-time Capable
DMAICELIMINATE
WASTE,
IMPROVECYCLE TIME
DESIGN
PREDICTIVE
QUALITY INTOPRODUCTS
ELIMINATE
DEFECTS,
REDUCEVARIABILITY
DFSS
Robust
Requirements allocation
Capability assessment
Robust Design
Predictable Product Quality
Design for Six Sigma
The I in DMAIC may become DFSSThe I in DMAIC may become DFSS
The Process Improvement Triad: DFSS, Lean, and DMAIC
Chapter 1 50Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
DFSS Matches Customer Needs
with Capability Mean and variability affects product performance and cost
Designers can predict costs and yields in the design phase
Consider mean and variability in the design phase Establish top level mean, variability and failure rate targets for
a design Rationally allocate mean, variability, and failure rate targets to
subsystem and component levels
Match requirements against process capability and identify gaps
Close gaps to optimize a producible design
Identify variability drivers and optimize designs or make designs robustto variability
Process capability impact design decisions
DFSS enhances product design methods.DFSS enhances product design methods.
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Chapter 1 51Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Lean Focuses on Waste Elimination
Definition
A set of methods and tools used to eliminate waste ina process
Lean helps identify anything not absolutely requiredto deliver a quality product on time.
Benefits of using Lean
Lean methods help reduce inventory, lead time, andcost
Lean methods increase productivity, quality, on time
delivery, capacity, and sales
Chapter 1 52Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc. 11
DMAIC Solves Problems by Using
Six Sigma Tools
DMAIC is a problem solving methodology
Use this method to solve problems:
Define problems in processes
Measure performance
Analyze causes of problems
Improve processesremove variations andnonvalue-added activities
Control processes so problems do not recur
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Chapter 1 53Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Six Sigma
DMAIC is closely related to the Shewhart
cycle (variously called the Deming cycle, orthe PDCA cycle)
Chapter 1 54Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
Quality Costs
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Chapter 1 55Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Legal Aspects of Quality
Product liability exposure
Concept of strict liability
1. Responsibility of both manufacturer and
seller/distributor
2. Advertising must be supported by valid data
Chapter 1 56Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.Copyright (c) 2005 John Wiley & Sons, Inc.
A strategic management process, focused along the
eight dimension of quality
Suppliers and supply chain management must be
involved
Must focus on all three components: Quality Planning,
Quality Assurance, and Quality Control and Improvement
Implementing Quality Improvement
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Chapter 1 57Introduction to Statistical Quality Control, 5th Edition by Douglas C. Montgomery.
Copyright (c) 2005 John Wiley & Sons, Inc.
Learning Objectives