Introduction to Statistical Quality Control, 4...

Introduction to Statistical Quality Control,

4th Edition

Introduction to Statistical

Quality Control, 4th Edition

Douglas C. Montgomery

Arizona State University


4th Edition

Chapter 1

Quality Improvement in the

Modern Business Environment


4th Edition

1-1. The Meaning of Quality and

Quality Improvement

1-1.1 Dimensions of Quality

1-1.2 Quality Engineering Technology


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• Performance

• Reliability

• Durability

• Serviceability

• Aesthetics

• Features

• Perceived Quality

• Conformance to

standards


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• Definitions of Quality

Quality means fitness for use

- quality of design

- quality of conformance

Quality is inversely proportional to

variability.


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• Quality Improvement

Quality improvement is the reduction of

variability in processes and products.

Alternatively, quality improvement is also

seen as “waste reduction”.


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1-1.1 Dimensions of Quality –

Transmission Example


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1-1.2 Quality Engineering

Terminology

Quality Characteristics

• Physical - length, weight, voltage, viscosity

• Sensory - taste, appearance, color

• Time Orientation - reliability, durability,

serviceability


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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.


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Terminology

Two types of data

• Attributes Data - discrete data, often in the

form of counts.

• Variables Data - continuous measurements

such as length, weight.


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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)


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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.


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Terminology

• Concurrent Engineering

Team approach to design. Specialists from

manufacturing, quality engineering,

management, etc. work together for product

or process improvement.


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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


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(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.


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• 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.


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1-3. Statistical Methods for

Quality Control and Improvement

Three major areas:

• Statistical process control (SPC)

• Design of experiments (DOX)

• Acceptance sampling


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Statistical ProcessControl (SPC)

• Control charts are

used for process

monitoring and

variability reduction.

• SPC is an on-line

quality control tool.


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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.


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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


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1-4. Other Aspects of Quality


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


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1-4. Other Aspects of Quality


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


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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


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.


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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.


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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


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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


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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

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