Introduction to Statistical Quality Control,
4th Edition
Introduction to Statistical
Quality Control, 4th Edition
Douglas C. Montgomery
Arizona State University
Introduction to Statistical Quality Control,
4th Edition
Chapter 1
Quality Improvement in the
Modern Business Environment
Introduction to Statistical Quality Control,
4th Edition
1-1. The Meaning of Quality and
Quality Improvement
1-1.1 Dimensions of Quality
1-1.2 Quality Engineering Technology
Introduction to Statistical Quality Control,
4th Edition
1-1.1 Dimensions of Quality
• Performance
• Reliability
• Durability
• Serviceability
• Aesthetics
• Features
• Perceived Quality
• Conformance to
standards
Introduction to Statistical Quality Control,
4th Edition
1-1.1 Dimensions of Quality
• Definitions of Quality
Quality means fitness for use
- quality of design
- quality of conformance
Quality is inversely proportional to
variability.
Introduction to Statistical Quality Control,
4th Edition
1-1.1 Dimensions of Quality
• Quality Improvement
Quality improvement is the reduction of
variability in processes and products.
Alternatively, quality improvement is also
seen as “waste reduction”.
Introduction to Statistical Quality Control,
4th Edition
1-1.1 Dimensions of Quality –
Transmission Example
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
Quality Characteristics
• Physical - length, weight, voltage, viscosity
• Sensory - taste, appearance, color
• Time Orientation - reliability, durability,
serviceability
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
Quality engineering is the set of operational,
managerial, and engineering activities that a
company uses to ensure that the quality
characteristics of a product are at the
nominal or required levels.
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
Two types of data
• Attributes Data - discrete data, often in the
form of counts.
• Variables Data - continuous measurements
such as length, weight.
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
Specifications
Quality characteristics being measured are
often compared to standards or
specifications.
• Nominal or target value
• Upper Specification Limit (USL)
• Lower Specification Limit (LSL)
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
• When a component or product does not meet specifications, they are considered to be nonconforming.
• A nonconforming product is considered defective if it has one or more defects.
• Defects are nonconformities that may seriously affect the safe or effective use of the product.
Introduction to Statistical Quality Control,
4th Edition
1-1.2 Quality Engineering
Terminology
• Concurrent Engineering
Team approach to design. Specialists from
manufacturing, quality engineering,
management, etc. work together for product
or process improvement.
Introduction to Statistical Quality Control,
4th Edition
1-2. A Brief History of Quality
Control and Improvement
(Refer to Table 1-1)
• Walter Shewhart (1924) introduced statistical control chart concepts.
• The American Society for Quality Control formed in 1946 (now known as the American Society for Quality (ASQ)).
• 1950s and 1960s saw an increase in reliability engineering, experimental design, and statistical quality control
Introduction to Statistical Quality Control,
4th Edition
1-2. A Brief History of Quality
Control and Improvement
(Refer to Table 1-1)
• Competition from foreign industries (Japan)
increases during the 1970s and 1980s.
• Statistical methods for quality improvement use
increases in the United States during the 1980s
• Total Quality Management (TQM) emerges
during 1970s and into the 1980s as an important
management tool to implement statistical methods.
Introduction to Statistical Quality Control,
4th Edition
1-2. A Brief History of Quality
Control and Improvement
• Malcolm Baldridge National Quality Award is
established in 1988.
• ISO 9000 certification activities increase in U.S.
industry in the 1990s.
• Motorola’s Six-Sigma initiative begins in the
1990s.
Introduction to Statistical Quality Control,
4th Edition
1-3. Statistical Methods for
Quality Control and Improvement
Three major areas:
• Statistical process control (SPC)
• Design of experiments (DOX)
• Acceptance sampling
Introduction to Statistical Quality Control,
4th Edition
1-3. Statistical Methods for
Quality Control and Improvement
Statistical ProcessControl (SPC)
• Control charts are
used for process
monitoring and
variability reduction.
• SPC is an on-line
quality control tool.
Introduction to Statistical Quality Control,
4th Edition
1-3. Statistical Methods for
Quality Control and Improvement
Design of Experiments
• Experimental design is an approach to
systematically varying the controllable input
factors in the process and determine the effect
these factors have on the output responses.
• Experimental designs are off-line quality tools.
• Crucial for variability reduction.
Introduction to Statistical Quality Control,
4th Edition
1-3. Statistical Methods for
Quality Control and Improvement
Acceptance Sampling
• Acceptance sampling is the inspection and classification of a sample of the product selected at random from a larger batch or lot and the ultimate decision about disposition of the lot.
• Two types:
1. Outgoing inspection - follows production
2. Incoming inspection - before use in production
Introduction to Statistical Quality Control,
4th Edition
1-4. Other Aspects of Quality
Control and Improvement
Total Quality Management (TQM)
• TQM is a managerial framework to accomplish quality improvement.
• Other names and related approaches:
– Company-Wide Quality Control (CWQC)
– Total Quality Assurance (TQA)
– Six-Sigma
Introduction to Statistical Quality Control,
4th Edition
1-4. Other Aspects of Quality
Control and Improvement
1-4.1 Quality Philosophy and Management
Strategies
1-4.2 The Link Between Quality and
Productivity
1-4.3 Quality Costs
1-4.4 Legal Aspects of Quality
1-4.5 Implementing Quality Improvement
Introduction to Statistical Quality Control,
4th Edition
1-4.1 Quality Philosophy and
Management Strategies
Three Important Leaders
• W. Edwards Deming
- Emphasis on statistical methods in quality improvement (see Deming’s 14 points)
• Joseph Juran
- Emphasis on managerial role in quality implementation
• Armand V. Feigenbaum
- Emphasis on organizational structure
Introduction to Statistical Quality Control,
4th Edition
1-4.1 Quality Philosophy and
Management Strategies
• Total Quality Management (TQM)
• Quality Standards and Registration
– ISO 9000
• Six Sigma
• Just-In-Time, Lean Manufacturing,
Poka-Yoke, etc.
Introduction to Statistical Quality Control,
4th Edition
1-4.2 The Link Between Quality
and Productivity
• Effective quality improvement can be
instrumental in increasing productivity and
reducing cost.
• The cost of achieving quality improvements
and increased productivity is often
negligible.
Introduction to Statistical Quality Control,
4th Edition
1-4.3 Quality Costs
Quality Costs are those categories of costs that are
associated with producing, identifying, avoiding,
or repairing products that do not meet
requirements. These costs are:
• Prevention Costs
• Appraisal Costs
• Internal Failure Costs
• External Failure Costs
Introduction to Statistical Quality Control,
4th Edition
1-4.4 Legal Aspects of Quality
The re-emergence of quality assurance as
an important business strategy is in
part a result of
1. Consumerism
2. Product Liability
Introduction to Statistical Quality Control,
4th Edition
1-4.5 Implementing Quality
Improvement
• Strategic Management of Quality
• Almost all successful efforts have been
management-driven.
• Too much emphasis on registration and
certification programs (ISO, QS)
– Insufficient focus on quality planning and design,
quality improvement, overemphasis on quality
assurance
– Poor use of available resources
