chapter 5 quality

To Accompany Ritzman & Krajewski, Foundations of Operations Management © 2003 Prentice-Hall, Inc. All rights reserved.

Chapter 5 Chapter 5

QualityQuality


Learning Objectives• Be Able to Apply Concepts in Learning

Goals• Determine Product Reliability• Construct and Interpret Control Charts• Determine Process Capability• Be Able to Use Equations Listed in End

of Chapter Equation Summary


TQMTQMWheelWheel

Customer satisfaction


Customer-DrivenCustomer-DrivenDefinitions of QualityDefinitions of Quality Conformance to SpecificationsConformance to Specifications ValueValue Fitness for UseFitness for Use SupportSupport Psychological ImpressionsPsychological Impressions


The Costs of The Costs of Poor QualityPoor Quality Prevention CostsPrevention Costs Appraisal CostsAppraisal Costs Internal Failure CostsInternal Failure Costs External Failure CostsExternal Failure Costs


EmployeeEmployeeInvolvementInvolvement Cultural ChangeCultural Change TeamsTeams Individual DevelopmentIndividual Development Awards and IncentivesAwards and Incentives


PlanPlan

DoDo

CheckCheck

ActAct

DemingDemingWheelWheel


ReliabilityReliabilityProduct reliabilityProduct reliability

rrss == ( (rr11)()(rr22) . . . () . . . (rrnn))wherewhere

rrss = = reliability of the complete reliability of the complete productproductnn = = number of subsystemsnumber of subsystemsrrnn = = reliability of the subsystem reliability of the subsystem or component or component nn





rrss = (0.99)(0.90)(0.85) = 0.76 = (0.99)(0.90)(0.85) = 0.76





rrss = (0.99)( = (0.99)(0.950.95)()(0.900.90) = ) = 0.850.85





rrss = (0.99)(0.95)(0.90) = 0.85 = (0.99)(0.95)(0.90) = 0.85


QualityQualityFunctionFunctionDeploymentDeployment

The House of QualityThe House of Quality



Voice of Voice of the the

CustomerCustomer




CustomerCustomer

Competitive Competitive AnalysisAnalysis




CustomerCustomer


EngineerEngineer





CustomerCustomer


EngineerEngineer

Trade-offsTrade-offs





CustomerCustomer


EngineerEngineer

CorrelationsCorrelationsCompetitive Competitive

AnalysisAnalysis





CustomerCustomer


EngineerEngineer

CorrelationsCorrelations






CustomerCustomer


EngineerEngineer


Technical ComparisonTechnical Comparison






CustomerCustomer



EngineerEngineer


Technical ComparisonTechnical Comparison



PlanningPlanning AnalysisAnalysis IntegrationIntegration ActionAction

BenchmarkingBenchmarking


Data Analysis Data Analysis ToolsTools

• ChecklistsChecklists• Histograms and Bar ChartsHistograms and Bar Charts• Pareto ChartsPareto Charts• Scatter DiagramsScatter Diagrams• Cause-and-Effect DiagramsCause-and-Effect Diagrams• GraphsGraphs


Wellington Fiber Board Co.Wellington Fiber Board Co.Tools for Improving QualityTools for Improving Quality

Step 1—ChecklistStep 1—Checklist Step 2—Pareto chartStep 2—Pareto chart Step 3—Cause-and-effect diagramStep 3—Cause-and-effect diagram Step 4—Bar chartStep 4—Bar chart


Wellington Fiber Board Co.Wellington Fiber Board Co.ChecklistsChecklists

Headliner Defects Defect type Tally Total

A. Tears in fabricB. Discolored fabricC. Broken fiber board

D. Ragged edges Total




A. Tears in fabricB. Discolored fabricC. Broken fiber board /





A. Tears in fabricB. Discolored fabricC. Broken fiber board //





A. Tears in fabric /B. Discolored fabricC. Broken fiber board //





A. Tears in fabric /B. Discolored fabricC. Broken fiber board //

D. Ragged edges / Total




A. Tears in fabric //// 4B. Discolored fabric /// 3C. Broken fiber board //// //// //// ////

//// //// //// / 36D. Ragged edges //// // 7

Total 50


Wellington Fiber Board Co.Wellington Fiber Board Co.Pareto ChartPareto Chart

Num

ber o

f def

ects

100

80

60

40

20

0

50

40

30

20

10

0

Cum

ulat

ive

perc

enta

ge

Defect type


Wellington Fiber Board Co.Wellington Fiber Board Co.Pareto ChartPareto Chart

Num

ber o

f def

ects

100

80

60

40

20

0

50

40

30

20

10

0

Cum

ulat

ive

perc

enta

ge

Defect type

C

DA B


Wellington Fiber Board Co.Wellington Fiber Board Co.Cause-and-Effect DiagramCause-and-Effect Diagram

Out of specification Not available

Training Absenteeism Communication

HumiditySchedule changes

Machine maintenance Machine speedWrong setup

Process

People

Other

Materials

Broken fiber

board


Wellington Fiber Board Co.Wellington Fiber Board Co.Bar ChartBar Chart

20

15

10

5

0

Num

ber o

f bro

ken

fiber

boa

rds

First Second ThirdShift


Sample Means and theSample Means and theProcess DistributionProcess Distribution

425 Grams

Mean

Processdistribution


Sample Means and theSample Means and theProcess DistributionProcess Distribution

Processdistribution

425 Grams

MeanDistribution ofsample means


Control ChartsControl ChartsUCL

Nominal

LCL



Nominal

LCL

1 2 3Samples



Nominal

LCL

Assignable causes likely

1 2 3Samples


Using Control Charts for Using Control Charts for Process ImprovementProcess Improvement

Measure the process When changes are indicated,

find the assignable cause Eliminate problems, incorporate

improvements Repeat the cycle


Control Chart ExamplesControl Chart Examples

Nominal

UCL

LCL

Sample number

Varia

tions


Control Charts TypesControl Charts Types• Control charts for attributes

– Yes/no– Off/on

• Control charts for variables– Length– Width– Weight


Control ChartsControl Chartsfor Variablesfor Variables

West Allis IndustriesWest Allis Industries



Sample SampleNumber 1 2 3 4

12345

Special Metal Screw



Sample SampleNumber 1 2 3 4

1 0.5014 0.5022 0.5009 0.50272 0.5021 0.5041 0.5024 0.50203 0.5018 0.5026 0.5035 0.50234 0.5008 0.5034 0.5024 0.50155 0.5041 0.5056 0.5034 0.5047

Special Metal Screw



Sample SampleNumber 1 2 3 4 R x

1 0.5014 0.5022 0.5009 0.50272 0.5021 0.5041 0.5024 0.50203 0.5018 0.5026 0.5035 0.50234 0.5008 0.5034 0.5024 0.50155 0.5041 0.5056 0.5034 0.5039

Special Metal Screw

_




1 0.5014 0.5022 0.5009 0.50272 0.5021 0.5041 0.5024 0.50203 0.5018 0.5026 0.5035 0.50234 0.5008 0.5034 0.5024 0.50155 0.5041 0.5056 0.5034 0.5039

0.5027 – 0.50090.5027 – 0.5009 == 0.00180.0018

Special Metal Screw

_




1 0.5014 0.5022 0.5009 0.5027 0.00182 0.5021 0.5041 0.5024 0.50203 0.5018 0.5026 0.5035 0.50234 0.5008 0.5034 0.5024 0.50155 0.5041 0.5056 0.5034 0.5039

0.5027 – 0.50090.5027 – 0.5009 == 0.00180.0018

Special Metal Screw

_




1 0.5014 0.5022 0.5009 0.5027 0.0018 0.50182 0.5021 0.5041 0.5024 0.50203 0.5018 0.5026 0.5035 0.50234 0.5008 0.5034 0.5024 0.50155 0.5041 0.5056 0.5034 0.5039

0.5027 – 0.50090.5027 – 0.5009 == 0.00180.0018(0.5014 + 0.5022 +(0.5014 + 0.5022 + 0.5009 + 0.5027)/40.5009 + 0.5027)/4 == 0.50180.5018

Special Metal Screw

_




1 0.5014 0.5022 0.5009 0.5027 0.0018 0.50182 0.5021 0.5041 0.5024 0.5020 0.0021 0.50273 0.5018 0.5026 0.5035 0.5023 0.0017 0.50264 0.5008 0.5034 0.5024 0.5015 0.0026 0.50205 0.5041 0.5056 0.5034 0.5047 0.0022 0.5045

Special Metal Screw

_




1 0.5014 0.5022 0.5009 0.5027 0.0018 0.50182 0.5021 0.5041 0.5024 0.5020 0.0021 0.50273 0.5018 0.5026 0.5035 0.5023 0.0017 0.50264 0.5008 0.5034 0.5024 0.5015 0.0026 0.50205 0.5041 0.5056 0.5034 0.5047 0.0022 0.5045

R = 0.0021x = 0.5027

Special Metal Screw

=

_



Control Charts – Special Metal ScrewR-Charts R = 0.0021

UCLR = D4RLCLR = D3R


Control ChartsControl Chartsfor Variablesfor Variables Control Chart FactorsControl Chart Factors

Factor for UCLFactor for UCL Factor forFactor for FactorFactorSize ofSize of and LCL forand LCL for LCL forLCL for UCL forUCL forSampleSample xx-Charts-Charts RR-Charts-Charts RR-Charts-Charts

((nn)) ((AA22)) ((DD33)) ((DD44))

22 1.8801.880 0 0 3.2673.26733 1.0231.023 0 0 2.5752.57544 0.7290.729 0 0 2.2822.28255 0.5770.577 0 0 2.1152.11566 0.4830.483 0 0 2.0042.00477 0.4190.419 0.076 0.076 1.9241.924



Control Charts - Special Metal ScrewR - Charts R = 0.0020 D4 = 2.2080

Control Chart FactorsControl Chart FactorsFactor for UCLFactor for UCL Factor forFactor for FactorFactor

Size ofSize of and LCL forand LCL for LCL forLCL for UCL forUCL forSampleSample xx-Charts-Charts RR-Charts-Charts RR-Charts-Charts

((nn)) ((AA22)) ((DD33)) ((DD44))

22 1.8801.880 0 0 3.2673.26733 1.0231.023 0 0 2.5752.57544 0.7290.729 0 0 2.2822.28255 0.5770.577 0 0 2.1152.11566 0.4830.483 0 0 2.0042.00477 0.4190.419 0.076 0.076 1.9241.924



Control Charts—Special Metal ScrewR-Charts R = 0.0021 D4 = 2.282

D3 = 0UCLR = D4RLCLR = D3R




D3 = 0

UCLR = 2.282 (0.0021) = 0.00479 in.





D3 = 0

UCLR = 2.282 (0.0021) = 0.00479 in.LCLR = 0 (0.0021) = 0 in.



Range Chart - Range Chart - Special Metal ScrewSpecial Metal Screw

| | | | | | | |0 1 2 3 4 5 6 7

0.005 -0.0045 -

0.004 -0.0035 -

0.003 -0.0025 -

0.002 -0.0015 -

0.001 -0.0005 -

0 -

Ran

ge

R-Chart

Sample Number

UCLR = 0.00479

LCLR = 0

R = 0.0021



Control Charts—Special Metal ScrewX-Charts

UCLx = x + A2RLCLx = x – A2R

==

R = 0.0021x = 0.5027=



Control Charts - Special Metal ScrewR = 0.0020x = 0.5025

x - Charts

UCLx = x + A2RLCLx = x - A2R

Control Chart FactorsControl Chart FactorsFactor for UCLFactor for UCL Factor forFactor for FactorFactor

Size ofSize of and LCL forand LCL for LCL forLCL for UCL forUCL forSampleSample xx-Charts-Charts RR-Charts-Charts RR-Charts-Charts

((nn)) ((AA22)) ((DD33)) ((DD44))

22 1.8801.880 00 3.2673.26733 1.0231.023 00 2.5752.57544 0.7290.729 00 2.2822.28255 0.5770.577 00 2.1152.11566 0.4830.483 00 2.0042.00477 0.4190.419 0.0760.076 1.9241.924



Control Charts—Special Metal Screwx- Charts


==

R = 0.0021 A2 = 0.729x = 0.5027=




UCLx = 0.5027 + 0.729 (0.0021) = 0.5042 in.


==

R = 0.0021 A2 = 0.729x = 0.5027=




UCLx = 0.5027 + 0.729 (0.0021) = 0.5042 in.LCLx = 0.5027 – 0.729 (0.0021) = 0.5012 in.


==

R = 0.0021 A2 = 0.729x = 0.5027=


xx-Chart—-Chart—Special Metal ScrewSpecial Metal Screw

| | | | | | | |0 1 2 3 4 5 6 7

0.505 -0.5045 -

0.504 -0.5035 -

0.503 -0.5025 -

0.502 -0.5015 -

0.501 -

Ave

rage

X-Bar Chart

Sample Number

UCLX = 0.5042

LCLX = 0.5012

X = 0.5027=

–

–


| | | | | | | |0 1 2 3 4 5 6 7

0.505 -0.5045 -

0.504 -0.5035 -

0.503 -0.5025 -

0.502 -0.5015 -

0.501 -

Ave

rage

X-Bar Chart

Sample Number

UCLX = 0.5042

LCLX = 0.5012

X = 0.5027=

–

–

xx-Chart— -Chart— Special Metal ScrewSpecial Metal Screw


| | | | | | | |0 1 2 3 4 5 6 7

0.505 -0.5045 -

0.504 -0.5035 -

0.503 -0.5025 -

0.502 -0.5015 -

0.501 -

Ave

rage

X-Bar Chart

Sample Number

UCLX = 0.5042

LCLX = 0.5012

X = 0.5027=

–

–

xx-Chart—-Chart—Special Metal ScrewSpecial Metal Screw

Measure the process Find the assignable cause Eliminate the problem Repeat the cycle


Control Chart for Control Chart for AttributesAttributes• p-chart

– Used for controlling the proportion of defectives generated by a process

• c-chart– Used for controlling the number of

defects when more than one defect can be present in a particular product or service


p-chart(1 )

where:n = sample sizep = historical average proportion defective or target value

pp pn

where:z = normal deviate (std dev)

p p

p p

UCL p z

LCL p z


c-chartc = mean of distribution

c standard deviation

where:z = normal deviate (std dev)

c

c

UCL c z c

LCL c z c


Process CapabilityProcess CapabilityNominalvalue

800 1000 1200 Hours

Upperspecification

Lowerspecification

Process distribution

(a) Process is capable


Process CapabilityProcess CapabilityNominalvalue

Hours

Upperspecification

Lowerspecification

Process distribution

(b) Process is not capable800 1000 1200


Process CapabilityProcess Capability

Lowerspecification

Mean

Upperspecification

Two sigma

Nominal value



Lowerspecification

Mean

Upperspecification

Four sigma

Two sigma

Nominal value



Lowerspecification

Mean

Upperspecification

Six sigma

Four sigma

Two sigma

Nominal value


ISOISO90009000

ISOISO1400014000


Category 1—Leadership

120 points Category 2—Strategic Planning

85 points Category 3—Customer and Market Focus

85 points Category 4—Information and Analysis

90 points Category 5—Human Resource Focus

85 points Category 6—Process Management

85 points Category 7—Business Results

450 points

Criteria for Criteria for Performance Performance ExcellenceExcellence


Leadership—Leadership—Leadership system, values, expectations, and public responsibilities

Strategic Planning—Strategic Planning—The effectiveness of strategic and business planning and deployment of plans, focusing on performance requirements

Customer and Market Focus—Customer and Market Focus—How the company determines customer and market requirements and achievescustomers satisfaction

Information and Analysis—Information and Analysis—The effectiveness of information systems to support customer driven

performance excellence and marketplace success

Human Resource Focus—Human Resource Focus—The success of efforts to realize the full potential of the work force to create a high-

performance organization

Process Management—Process Management—The effectiveness of systems and processes for assuring the quality of products and services

Business Results—Business Results—Performance results and competitive benchmarking in customer satisfaction, financials, human resources, suppliers, and operations

chapter 5 quality

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