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Quality And PerformanceQuality And Performance5

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Total Quality ManagementTotal Quality Management

Figure 5.1 – TQM Wheel

Customer satisfaction

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The Deming WheelThe Deming Wheel

Plan

Do

Study

Act

Figure 5.2 – Plan-Do-Study-Act Cycle

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Six Sigma: average and varianceSix Sigma: average and variance

X X

X X

XX

XX X

XXXXX XXX

Process average OK;too much variation

Process variability OK;process off target

Processon target withlow variabilityReduce

spreadCenter

process

X

X

X

X

X

X X

X

X

Figure 5.3 – Six-Sigma Approach Focuses on Reducing Spread and Centering the Process

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Six Sigma Improvement ModelSix Sigma Improvement Model

Control

Improve

Analyze

Measure

Define

Figure 5.4 – Six Sigma Improvement Model

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Sample and Process DistributionsSample and Process Distributions

Distribution ofsample means

25 Time

Mean

Process distribution

Figure 5.6 – Relationship Between the Distribution of Sample Means and the Process Distribution

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Assignable CausesAssignable Causes

(a) LocationTime

Average

Figure 5.7 – Effects of Assignable Causes on the Process Distribution for the Lab Analysis Process

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Assignable CausesAssignable Causes

(b) SpreadTime

Average

Figure 5.7 – Effects of Assignable Causes on the Process Distribution for the Lab Analysis Process

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Assignable CausesAssignable Causes

(c) ShapeTime

Average

Figure 5.7 – Effects of Assignable Causes on the Process Distribution for the Lab Analysis Process

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Control ChartsControl Charts

Samples

Assignable causes likely

1 2 3

Figure 5.8 – How Control Limits Relate to the Sampling Distribution: Observations from Three Samples

UCL

Nominal

LCL

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Nominal

UCL

LCL

Var

iati

on

s

Sample number

Control ChartsControl Charts

Figure 5.9 – Control Chart Examples

(a) Normal – No action

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Nominal

UCL

LCL

Var

iati

on

s

Sample number

Control ChartsControl Charts

Figure 5.9 – Control Chart Examples

(b) Run – Take action

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Nominal

UCL

LCL

Var

iati

on

s

Sample number

Control ChartsControl Charts

Figure 5.9 – Control Chart Examples

(c) Sudden change – Monitor

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Nominal

UCL

LCL

Var

iati

on

s

Sample number

Control ChartsControl Charts

Figure 5.9 – Control Chart Examples

(d) Exceeds control limits – Take action

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Control Chart FactorsControl Chart Factors

TABLE 5.1 | FACTORS FOR CALCULATING THREE-SIGMA LIMITS FOR

| THE x-CHART AND R-CHART

Size of Sample (n)

Factor for UCL and LCL for x-Chart (A2)

Factor for LCL for R-Chart (D3)

Factor for UCL for R-Chart (D4)

2 1.880 0 3.267

3 1.023 0 2.575

4 0.729 0 2.282

5 0.577 0 2.115

6 0.483 0 2.004

7 0.419 0.076 1.924

8 0.373 0.136 1.864

9 0.337 0.184 1.816

10 0.308 0.223 1.777

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Process CapabilityProcess Capability

20 25 30 Minutes

Upperspecification

Lowerspecification

Nominalvalue

(a) Process is capable

Process distribution

Figure 5.14 – The Relationship Between a Process Distribution and Upper and Lower Specifications

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Process CapabilityProcess Capability

20 25 30 Minutes

Upperspecification

Lowerspecification

Nominalvalue

(b) Process is not capable

Figure 5.14 – The Relationship Between a Process Distribution and Upper and Lower Specifications

Process distribution

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Process CapabilityProcess Capability

Figure 5.15 – Effects of Reducing Variability on Process Capability

Lowerspecification

Mean

Upperspecification

Nominal value

Six sigma

Four sigma

Two sigma

•Two-sigma quality: 4.56% defects (45,600 defects/million)•Three-sigma quality: 0.26% defects (2,600 defects/million)•Four-sigma: 0.0063% defects (63 defects/million)•Six-sigma : 0.0000002% defects (0.002 defects/million)

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Quality EngineeringQuality Engineering

Lo

ss (

do

llars

)

Lower Nominal Upperspecification value specification

Figure 5.16 – Taguchi’s Quality Loss Function

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The Baldrige AwardThe Baldrige Award

The seven categories of the award are1. Leadership (120 points)

2. Strategic Planning (85 points)

3. Customer and Market Focus (85 points)

4. Measurement, Analysis, and Knowledge Management (90 points)

5. Workforce Focus (85 points)

6. Process Management (85 points)

7. Results (450 points)

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