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Chapter 4

Six Sigma Continuous Improvement

“The signifi cant problems we face cannot be solved at the same level of thinking we were at when we created them.”

—Albert Einstein

4.1 SIX SIGMA CONTINUOUS IMPROVEMENT PRINCIPLES

Advancement to near perfection (maximum profi tability) is virtually impos-sible without integration of proper engineering design, material, process, and control strategies—in other words, achieving higher standard deviations in exist-ing and future production processes. Six Sigma tools uncover the unseen root causes of potential problems and attack them to eliminate defect opportunities. This means that Six Sigma takes the necessary measurements at the early stages of product or process development before the problem occurs. Alternatively, it will focus on the processes indicating that their sigma level is either too low and cannot improve or a high sigma level (5 or more), which is too challenging to improve. One should keep in mind that the cost of redesign or correcting after-math problems is extremely high and costly. (See Chapter 8 for more details.)

Six Sigma can be achieved only with cross-functional groups or joint efforts throughout the organization with great intensity—that is, if it is required by corporate culture and deployed fi rmly. Indeed, Six Sigma has to be applied from raw material all the way to the fi nished product and the shipping department.

Essentials of Lean Six SigmaCopyright © 2006 by Academic Press, Inc. All rights of reproduction in any form reserved. 43

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44 Six Sigma Continuous Improvement

The performance of this is shown in Figure 4.1, the Six Sigma breakthrough model, with three main objectives: higher profi t, increased value, and reduced variation. Six Sigma science of continuous improvement concentrates on two processes that each include three steps:

Process Characterization

1. Defi ne project and process measurement (diagnosis)2. Evaluate existing sigma (capability study)3. Analyze process data

Process Optimization/Simulation

4. Improve and optimize process5. Evaluate new sigma (capability study)6. Control and maintain the process

Or the above steps can be summarized in DMAIC (defi ne/measure [diagnosis], analyze, improve [optimize], control).

4.2 SIX SIGMA SYSTEMS

Six Sigma systems include the following concepts:

1. The fastest rate of improvement in customer satisfaction, cost, quality, process speed, and invested capital.

2. A business improvement and growth system, which leads to a new level of performance.

Six-SigmaPerformance

ProcessManagement

CustomerDriven

StatisticalAnalysis

Higher Profits

Increased Value

Reduced Variation

Six-SigmaPerformance

ProcessManagement

CustomerDriven

StatisticalAnalysis

Higher Profits

Increased Value

Reduced Variation

Figure 4.1 Six Sigma breakthrough performance model.


Six Sigma Continuous Improvement 45

3. A systematic data-driven approach to analyzing the root cause of manufacturing, as well as business problems/processes and dramatically improving them.

4. Improved decisions based on knowledge and data. 5. A fi nancial results-driven system ($ performance paramount). 6. A project-driven system based on customer needs. 7. A system applicable to all parts of a business. 8. Aimed at the problem where the solution is not known. 9. A system with proven performance.10. Improve customer satisfaction and supplier relationships.11. Expand knowledge of product and processes.12. Develop a common set of tools and improvement techniques.

Figure 4.2 illustrates the graphical representation of Six Sigma improvement steps.

4.3 SIX SIGMA IMPROVEMENT AND TRAINING MODELS

One may obtain Six Sigma training certifi cation by completing the improve-ment models for Green Belt and Black Belt. These trainings are available through academic institutions, as well as quality societies or other certifi ed organizations.

Figure 4.2 Representation of Six Sigma defi ne and measure, analyze, improve or optimize, and control (DMAIC) levels.

Six SigmaApproach

Process ControlAnd Maintain

Improve Process Estimate New Sigma

Process Optimization (New Process)

Analyze Data

Define Project Measure Process

Estimate Existing Sigma

ProcessCharacterization

(Existing Process)



Figure 4.3 Six Sigma Green Belt improvement model.

ObjectiveD

efin

e Identify Business DriversSelect Customer Critical ProcessesDefine ProjectsDevelop Implementation Plan

Affinity Diagram/Interrelation DiagramQuality Function DeploymentSIPOC Process MapProject Charter

Mea

sure

Develop Key Process MeasuresCollect and Analyze DataIdentify the Vital Few that Have the Greatest ImpactEstimate Process CapabilityMeasurement Systems Analysis

Data Collection PlanCheck/Data SheetPareto ChartGage R&RHistogramProcess Capability

An

alyz

e Understand Cause and EffectsCreate Multi-vari AnalysisDetermine Variance ComponentsAssess Correlation

Cause and Effect DiagramScatter Diagram

Imp

rove Develop and Evaluate Solutions

Implement Variation ReductionStandardize ProcessAssess Risk Factors

Deployment FlowchartTree DiagramFMEA

Co

ntr

ol Implement Process Control

Implement Control Charts for Key VariablesMistake Proof ProcessesEvaluate Results

Process Control PlanControl/Precontrol ChartPoka-YokePareto Chart (ongoing)Process Capability (ongoing)

Tools and Techniques

Manpower Materials

MethodsMachines

Variation/Opportunity

Calibration

Available Resources

Training

Wrong Selection

Maintenance

Hardness

Surface Finish

Outdated Practices

Availability

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

A B 1 A B 2 A B 3 A B 4 A B 5

Idea Idea

Idea Idea

Idea Idea

Idea

IdeaIdea Idea

Idea Idea

Idea

Idea

IdeaIdea Idea

Idea Idea

Idea Idea

THEME THEME THEME

In = 1 Out = 3 In = 2 Out = 2

In = 3 Out = 1

In = 2 Out = 2

Production

ControlSystems

ChangedWorkEnvironment

OrganizationalStructure

Communication

WorkplaceMotivation/Conflict

CustomerExpectations/

Satisfaction

In = 1 Out = 4

In = 4 Out = 1

Driver (Cause) Outcome (Effect)

Start

Finish

Decision

Task

TaskTask

Task

Task

Finish

Y

N

S u b- G o a l

S u b - G o a l

S u b- G o a l

A cti v i ty

A cti v i ty

A cti v i ty

A cti v i ty

A cti v i ty

A cti v i ty

A cti v i ty

G o a l

0

10

20

30

40

50

60

70

2 4 6 8 10 12 14 16

Relationship

MatrixWhats

Hows

QFD

Cp & CpK

Rev#Date by¦2/96

Process DescriptionProcess CustomerProcess FlowchartJob

Time

IndicatorsControl

LimitsSpecs/

Targets

AND

CHECKINGMisc

Checking

Item

Fre-

quency

Respon-

sibility Conting.

Plan

When to

Check

Who

Checks

00:00

Customer Front Desk

Cook Delivery

Orders Pizza

Takes OrderPasses to Cook

Loads Pizza

Cooks Pizza

DeliverDone?Pay for Pizza

01:30

04:3010:15

11:30

35:30

P1 Time

stamp

P3 P3

Into Oven

Each

order

Cook

PrintingEach

order

Front

Cook11 minutes

30 seconds

Ticket on

oven

Cook

Each

Insertion

Q1 Q2

noyes

Process Control PlanUCL

x

LCL

Day 1

1111 111 1 11111

1 11111 111 111

111 111 1111 111

Day 3Day 2 Day 4

Paint

Perf

Test

S I P O C

NoMistakes

Failure Mode Effects Analysis

RiskPrioritization

Number

Variable X

Variable Y


Six Sigma Continuous Improvement 47

Objective

Def

ine

Identify Business DriversSelect Customer Critical ProcessesDefine ProjectsDevelop Implementation Plan

Affinity Diagram/Interrelation DiagramQuality Function DeploymentSIPOC Process MapProject Charter

Mea

sure

Develop Key Process MeasuresCollect and Analyze DataIdentify the Vital Few that Have the Greatest ImpactEstimate Process CapabilityMeasurement Systems Analysis

Data Collection PlanCheck/Data SheetPareto ChartGage R&RHistogramProcess Capability

Ana

lyze

Understand Cause and EffectsCreate Multi-vari AnalysisDetermine Variance ComponentsAssess Correlation

Cause and Effect DiagramMulti-vari ChartsScatter Diagram

Impr

ove Develop and Evaluate Solutions

Implement Variation ReductionStandardize ProcessAssess Risk Factors

Design of ExperimentsDeployment FlowchartTree DiagramFMEA

Con

trol

Implement Process ControlImplement Control Charts for Key VariablesMistake Proof ProcessesEvaluate Results

Process Control PlanControl/Precontrol ChartPoka-YokePareto Chart (ongoing)Process Capability (ongoing)

Tools and Techniques

Manpower Materials

MethodsMachines

Variation/Opportunity

Calibr at ion

Available Resour ces

T rainin g

Wr ong S elect ion

Main ten an ce

Har dness

S ur f ace Fin ish

Out dat ed P ractices

Availabilit y

0

10

20

30

40

50

60

70

AB1 AB2 AB3 AB4 AB5

Idea Idea

Idea Idea

Idea Idea

Idea

IdeaIdea Idea

Idea Idea

Idea

Idea

IdeaIdea Idea

Idea Idea

Idea Idea

THEME THEME THEME

In = 1 Out =3 In = 2 Out = 2

In = 3 Out = 1

In = 2 Out = 2

Production

ControS ystem

ChangeWorkEnvironmen

OrganizationaStructure

Communication

Work placeMotivationConflic

Cust omeExpectationS atisfaction

In = 1 Out = 4 In = 4 Out = 1

Driver (Cause)

Start

F i ni s h

Decision

Task

Finish

Y

N

S u b -G o a l

S u b -G o a l

S u b -G o a l

A c tiv ity

A c tiv ity

A c tiv ity

A c tiv ity

A c tiv ity

A c tiv ity

A c tiv ity

G oa l

0

10

20

30

40

50

60

70

2 4 6 8 10 12 14 16

Factor A

Factor C

HighLow

High

Low

1.1 1.2 1.3 2.1 2.2 2.3

X

Variable X

Variable Y

Relationship

Matr i x

Whats

Hows

QFD

Cp & CpK

R ev#Dat e by¦2 / 9 6

P rocess Descr ipt ionP rocess Cust omerP rocess Flowchar tJob

T imeI ndicat or s

Con tr o

Limit s

S pecs/

T ar get s

AND

CHE CK I NGMisc

Checkin g

I tem

Fre-

quen cy

R espon -

s ibilit y Con tin g.

P lan

When t o

Check

Who

Checks

0 0 : 00

Cust omer Fron t Desk

Cook Delivery

Order s Pizza

T akes OrderP asses t o Cook

Loads P izza

Cooks P izza

DeliverDon e?P ay for Pizza

0 1: 30

0 4 : 3010 : 15

11: 3 0

3 5 : 30

P 1 T ime

stamp

P 3 P 3

I nt o Oven

E ach

order

Cook

P r in t in gE ach

order

Fron t

Cook11 minut es

3 0 seconds

T icket on

oven

Cook

E ach

I nser t ion

Q1Q2

n o

yes

Process Control PlanUCL

x

LCL

Day1

1111 111 1 11111

1 11111 111 111

111 111 1111 111

Day 3Day 2 Day 4

Paint

Perf

Test

S I P O C

NoM is t akes

Failure Mode Effects Analysis

R iskPrioritization

Number

Task

Task

Task Task

Factor B

d

Outcome (Effect)

Figure 4.4 Six Sigma Black Belt improvement model.

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On the other hand, you can apply all the procedures and guidelines of this book to any desired projects. Once you have knowledge and experience, you can participate in certifi ed examinations through a quality organization. The training models for the Green Belt and Black Belt are cited in Figures 4.3 and 4.4. The details of these models are discussed in Chapter 8.


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