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SMUEMIS 7364

NTUTO-570-N

Basic Conceptsupdated 1.14.04

Statistical Quality ControlDr. Jerrell T. Stracener, SAE Fellow

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Statistical Quality Control - Basic Concepts

• Introduction and basic concepts

• Statistical analysis of process capability

• Statistical process control

• Process design and improvement

• Sampling

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Statistical Quality Control - Basic Concepts

I will explain the role of quality throughout theproduct life cycle (engineering and design, manufacturing/production and support) to:

increase the relevance of techniques and methods

increase your ability to apply techniques and methods

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Statistical Quality Control - Basic Concepts

The concepts, techniques and methods are coveredin this course are applicable (with tailoring)

to all products: hardware, software, service

over the product life cycle

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Statistical Quality Control - Basic Concepts

• What is quality?

• What are the features of quality?

• How is quality measured?

• How do we know the level of quality?

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Statistical Quality Control - Basic Concepts

This course is statistical quality control

It is not a statistics course

It is an application of statistical techniques toquality control

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Statistical Quality Control - Basic Concepts

Introduction and basic concepts

Fundamental concepts of qualityDimensions of qualityQuality metricsTotal quality managementBasic concepts of statistical quality controlQuality improvement toolsSix Sigma concepts

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Statistical Quality Control - Basic Concepts

Analysisof processcapability

Statisticalprocesscontrol

Processimprovement

Acceptancesampling

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Statistical Quality Control - Basic Concepts

• Quality begins with customer requirements

• Quality must be designed in. It cannot be inspected in!

• Quality depends on:

Parts selection and procurementMaterialManufacturing/production processesLogistic processes

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Statistical Quality Control - Basic Concepts

• 19901. Reliability2. Durability3. Easy maintenance4. Ease of use5. A known or trusted brand name6. Low price

• 19851. A well known brand name2. Workmanship3. Low price

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Statistical Quality Control - Basic Concepts

• The glow and tingle factorWhich makes a customer choose one productover another when their quality is equal

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Dimensions of Quality

• Performance - Will it do the intended job?• Reliability - How often does it fail?• Durability - How long does the product last?• Serviceability - How easy is it to repair the product?• Aesthetics - What does the product look like?• Features - What does the product do?• Perceived Quality - What is the reputation of thecompany or its product?• Conformance to Standards - Is the product madeexactly as the designer intended?

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The Level of Quality

The Goodness Level of 99% Equates to:• 20,000 lost articles of mail per hour• Unsafe drinking water almost 15 minutes per day• 5000 incorrect surgical operations per week• 2 short of long landings at most major airportsper day• 200,000 wrong drug prescriptions each year• No electricity for almost 7 hours per month

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Statistical Quality Control - What is quality?

• Quality is meeting the customer’s needs over thelife cycle of the product at the best value to the customer

• Quality has many dimensions

ReliabilityMaintainabilityPerformanceDurabilityConformance (to requirements and expectations)

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Obstacles to Quality Improvement

• Making it happen- 99% agree that management is the problemnot the workers- 35% of the problem is ‘not invented here’ syndrome

getting their attention and educationresistance to change

- 15% gaining management commitment- 14% communication

getting the word out within the company

• Failure of management to understand ‘variation’

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How TQM Works

• Builds and sustains a culture committed to continuous improvement• Focuses on satisfying service needs and expectations• Requires dedication, commitment, and participationfrom top DoD leadership• Involves every individual in improving his/her ownprocesses• Creates teamwork and constructive working relationships• Recognizes people as the most important resource• Employs the best available management practices,and tools

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TQM Principles

• Continuous process improvement- Implemented through a structured anddisciplined approval- Emphasis is placed on preventing defects

• Process knowledge- Change is created by those who understandthe process

• User focus- Understand the needs of all users

• Commitment- Requires commitment at all levels, startingat the top

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True Impact of Product Variability

• Loss function - dollar loss due to deviation of product from ‘ideal’ characteristic

- dimension- surface finish- elasticity- gain- other

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True Impact of Product Variability

• Sources of loss- scrap- rework- warranty obligations- decline of reputation- forfeiture of market share

• Loss characteristic is continuous - not a step function

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Key Elements of VRP

• Sources of loss- scrap- rework- warranty obligations- decline of reputation- forfeiture of market share

• Loss characteristic is continuous - not a step function

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