six sigma for process quality improvement 1233779323024526 3

7/29/2019 Six Sigma for Process Quality Improvement 1233779323024526 3

1/76

Chapter 4: Six Sigma for Process and QualityImprovement 1

Chapter 4

Six Sigma For Process &

Quality Improvement


2/76


Quality Management and Six

Sigma in Perspective

Two primary sets of costs are involvedin quality:

control costs

failure costs

Costs broken into four categories:

Prevention costs

Appraisal costs Internal costs of defects

External costs of defects


3/76


Japanese Approaches to Quality

In 1950 the Japanese government

invited W. Edwards Deming (then a

professor at New York University) togive a series of lectures on quality

control to help Japanese engineers

reindustrialize the country.


4/76


W. Edwards Deming

Major source of poor quality is

variat ion

Quality improvement the responsibilityof top management

All employees should be trained in use

of problem solving tools and especiallystatistical techniques


5/76


Demings 14 Points

1. Create constancy of purpose

2. Adopt the new philosophy

3. Cease dependence on mass inspection4. End practice of awarding business on

basis of price tags

5. Improve constantly and forever6. Institute modern methods of training


6/76


Demings 14 Points continued

7. Institute modern method of

supervision

8. Drive out fear9. Breakdown organizational barriers

10. Eliminate arbitrary numerical goals

11. Eliminate work standards and quotas

12. Remove barriers that reduce pride of

workmanship


7/76


Demings 14 Points continued

13. Institute a vigorous program of

education and training

14. Push the 13 points everyday


8/76


Total Quality Management (TQM)

Better to produce item right the first

time than to try to inspect quality in

Quali ty at the sou rce- responsibilityshifted from quality control department

to workers


9/76


History of TQM

Dr. Shewart began using statistical

control at the Bell Institute in 1930s

Military standards developed in 1950s After World War II, Japanese Union of

Scientist and Engineers began

consulting with Deming Deming Prize introduced in Japan in

1951


10/76


History of TQM continued

Quality assurance concept proposed in 1952

Juran makes first trip to Japan in 1954

Quality becomes Japans national slogan in

1956

First quality circles created in 1957

10,000 quality circles by 1966

100,000 quality circles by 1977

First U.S. quality circle 1974


11/76


Five Steps in TQM

Determine what customers want

Develop products and services

Develop production system

Monitor the system

Include customers and suppliers


12/76


Joseph Juran

Quality Control Handbook(1951)

Employees speak in different languages

Quality Trilogy Quality Planning

Quality Control

Quality Improvement

Need to place more emphasis on

planning and improvement


13/76


Joseph Juran continued

Organizations progress through four

phases

Minimize prevention and appraisal costs

Appraisal costs increased

Process control introduced increasing

appraisal costs but lowering internal and

external failure costs

Prevention costs increased in effort to

lower total quality costs


14/76

Chapter 4: Six Sigma for Process and Quality

Improvement

14

A Brief History of Six Sigma

The Six Sigma concept was developed byBill Smith, a senior engineer at Motorola, in1986 as a way to standardize the way

defects were tallied. Sigma is the Greek symbol used in statistics

to refer to standard deviation which is ameasure of variation.

Adding six to sigma combines a measureof process performance (sigma) with thegoal of nearly perfect quality (six).


15/76


Improvement

15

A Brief History of Six Sigma

continued

In the popular book The Six SigmaWay, Six Sigma is defined as:

a comprehensive and flexible system for

achieving, sustaining and maximizingbusiness success. Six Sigma is uniquelydriven by close understanding of customerneeds, disciplined use of facts, data, and

statistical analysis, and diligent attention tomanaging, improving, and reinventingbusiness processes. (p. xi)


16/76


Improvement

16

The DMAIC Improvement Process

Six Sigma projects generally follow awell defined process consisting of fivephases.

define

measure

analyze

improve control

pronounced dey-MAY-ihk


17/76


Improvement

17

The DMAIC Improvement Process


18/76

Chapter 4: Six Sigma for Processand Quality Improvement

18


19/76


Improvement

19

The Define Phase

The define phase of a DMAIC project focuses

on clearly specifying the problem or

opportunity, what the goals are for the

process improvement project, and what thescope of the project is. Identifying who the

customer is and their requirements is also

critical given that the overarching goal for all

Six Sigma projects is improving the

organizations ability to meet the needs of its

customers.


20/76


Improvement

20

Defining and Measuring Quality

Conformance to specifications

Performance

Quick response

Quick-change expertise

Features Reliability

Durability

Serviceability

Aesthetics Perceived quality

Humanity

Value


21/76


Improvement

21

Benchmarking

Benchmarking involves comparing an

organization's processes with the best

practices to be found. Benchmarking is

used for a variety of purposes, including: Comparing an organization's processes

with the best organization's processes.

Comparing an organization's products andservices with those of other organizations.


22/76


Improvement

22

Benchmarking continued

Identifying the best practices to

implement.

Projecting trends in order to be able torespond proactively to future

challenges and opportunities.


23/76


Improvement

23

Quality Function Deployment (QFD)

Two key drivers of an organizations long-

term competitive success are the extent to

which its new products or services meetcustomers needs, and having the

organizational capabilities to develop and

deliver such new products and services.

Tools for helping translate customer desiresdirectly into product service attributes.


24/76


Improvement

24

Four Houses of Quality

Customer requirements

Technical requirements

Component requirements

Process deployment requirements


25/76


Improvement

25

House of Quality Details


26/76


Improvement

26

The Measure Phase

The measure phase begins with the

identification of the key process performance

metrics.

Once the key process performance metrics

have been specified, related process and

customer data is collected.

Two commonly used process performancemeasures, namely, Defects per Million

Opportunities (DPMO) and Process Sigma.


27/76


Improvement

27

Defects Per Million Opportunities

Earlier it was noted that a literal

interpretation of Six Sigma is 3.4

defects per million opportunities(DPMO). This may have caused some

confusion for more statistically inclined

readers, which we shall now attempt toreconcile.


28/76


Improvement

28

Defects Per Million Opportunities


29/76


Improvement

29

Process Sigma

How sigma itself can be used to

measure the performance of a

process. One way to measure the performance of

a process is to calculate the number of

standard deviations the customer

requirements are from the process mean

or target value.


30/76


Improvement

30

DPMO for Alternative Process Sigma Levels


31/76


Improvement

31

Motorolas Assumption the Process Mean Can

Shift by as Much as 1.5 Standard Deviations


32/76


Improvement

32

Comparison of 3 Sigma Process and 6 Sigma Process


33/76


Improvement

33

The Analyze Phase

In this phase our objective is to utilizethe data that has been collected to

develop and test theories related to theroot causes of existing gaps betweenthe process current performance andits desired performance.

See next slide Table 4.3 Commontools and methodologies in the SixSigma toolset.


34/76


Improvement

34

Brainstorming

The brainstorming approach:

Do not criticize ideas during the

brainstorming session.

Express all ideas no matter how radical,

bizarre, unconventional, ridiculous, or

impractical they may seem.

Generate as many ideas as possible. Combine, extend, and/or improve on one

anothers ideas.


35/76


Improvement

35

Brainstorming: Actions to Enhance

Team Creativity

Create diversified teams.

Use analogical reasoning.

Use brain writing.

Use the Nominal Group Technique.

Record team ideas.

Use trained facilitators to run the brainstormingsession.

Set high standards.

Change the composition of the team.

Use electronic brainstorming.

Make the workplace a playground.


36/76


Improvement

36

Cause and Effect Diagrams


37/76


Improvement

37

Process Capability Analysis

Process Capabilit Anal sis


38/76


Improvement

38

Process Capability Analysis

continued


39/76


Improvement

39

The Improve Phase: Design of

Experiments (DOE)

OFAT and 1FAT - one factor at a time.

Shortcomings

Not typically possible to test one factor at atime and hold all the other factors constant.

Not possible to account for interactions or

joint variation between variables (Figure

4.16).


40/76


Improvement

40

Design of Experiments (DOE)


41/76


Improvement

41

DOE: continued


42/76


Improvement

42

DOE: continued


43/76


Improvement

43

DOE continued

Some of the major considerations

associated with DOE include:

Determining which factors to include inthe experiment.

Specifying the levels for each factor.

Determining how much data to collect. Determining the type of experimental

design.


44/76


Improvement

44

Taguchi Methods

Design fo r Manu factu rabi l i ty (DFM)

Procedure for statistical testing to

determine best combination of productand transformation system design that

will make output relatively independent

of normal fluctuations in the productionsystem


45/76


Improvement

45

Statistical Quality Control


46/76


Improvement

46

Chance Versus Assignable Variation

Chance variationis variability built into

the system.

Ass ignable var iat ionoccurs becausesome element of the system or some

operating condition is out of control.

Quality control seeks to identify whenassignable variation is present so that

corrective action can be taken.

C l B d A ib d


47/76


Improvement

47

Control Based on Attributes and

Variables

Inspect ion fo r Variables:measuring a

variable that can be scaled such as

weight, length, temperature, and

diameter.

Inspect ion of A t t r ibu tes:determining

the existence of a characteristic such as

acceptable-defective, timely-late, and

right-wrong.


48/76


Improvement

48

Control Charts


49/76


Improvement

49

Control Charts

Developed in 1920s to distinguish

between chance variation in a system

and variation caused by the systemsbeing out of control - assignable

variation.


50/76


Improvement

50

Control Charts continued

Repetitive operation will not produceexactly the same outputs.

Pattern of variability often described by

normal distribution. Random samples that fully represent the

population being checked are taken.

Sample data plotted on control charts todetermine if the process is still under

control.

C t l Ch t ith Li it S t t Th St d d


51/76


Improvement

51

Control Chart with Limits Set at Three Standard

Deviations


52/76


Improvement

52

Control Charts for Variables


53/76


Improvement

53

Two Control Charts

Sample Means Chart

Range Chart

S l D t f W i ht f T


54/76


Improvement

54

Sample Data of Weights of Tacos

(Ounces)

Sample Scenario 1 Scenario 2

1 4, 5, 6 4, 5, 6

2 6, 7, 8 3, 5, 7

3 7, 8, 9 2, 5, 8


55/76


Improvement

55

Analysis of Scenario 1

Sample Mean Range

1 5 2

2 7 2

3 8 2

Sample means show problem having increased from 5

ounces to 8 ounces. Sample ranges have not changed

from sample to sample.


56/76


Improvement

56

Analysis of Scenario 2

Sample Mean Range

1 5 2

2 5 4

3 5 6Sample ranges show problem having increased from 2ounces to 6 ounces. Sample means have not changed

from sample to sample.


57/76


Improvement

57

Patterns of Change in Process Distributions


58/76


Improvement

58

Control Limits

Sample Means Chart:

RAXLCL

RAXUCL

2X

2X

Range Chart:

RDLCL

RDUCL

3R

4R

Calculating the Grand Mean and the


59/76


Improvement

59

Calculating the Grand Mean and the

Average Range

N

R

R

N

XX


60/76


Improvement

60

Mean Age of Ice Cream


61/76


Improvement

61

Range in Ice Cream Age


62/76


Improvement

62

Control Charts for Attributes


63/76


Improvement

63

Fraction-Defective (p) Charts

pp

pp

p

zp

zp

n

pp

p

LCL

UCL

)1(

sampledunitsofnumbertotal

defectsofnumbertotal


64/76


Improvement

64

Number-of-Defects (c) Charts

cc

cc

c

zc

zc

c

c

LCLUCL

sampledunitsofnumber

observedincidentsofnumber


65/76


Improvement

65

Six Sigma in Practice

Six Sigma Roles:

Master Black Belts.

Black Belts.

Green Belts.

Yellow Belts.

Supporting Roles:

Champions/Sponsors.

Process owners.


66/76


Improvement

66

Quality in Services

Measuring is difficult

Training in standard procedures oftenused to improve quality

One way to measure quality of servicesis to use customer satisfaction surveys

J.D. Power and Associates uses

surveys to rate domestic airlines, hotelchains, and rental car companies.

R ti th P f f D ti


67/76


Improvement

67

Rating the Performance of Domestic

Airlines

On-time performance (25%)

Airport check-in (11%)

Courtesy of flight attendants (11%)

Seating comfort (11%)


68/76


Improvement

68

Service Defections

Organizations should monitor

customer defections

feedback from defecting customers canbe used to identify problem areas

can determine what is needed to win

them back

changes in defection rate can be used as

early warning signal


69/76


Improvement

69

Quality Awards/Certifications

The Malcolm Baldrige National Quality


70/76


Improvement

70

The Malcolm Baldrige National Quality

Award


71/76


Improvement

71

ISO 9000

Guidelines for designing,

manufacturing, selling, and servicing

products. Selecting an ISO 9000 certified

supplier provides some assurance that

supplier follows accepted businesspractices in areas covered by the

standard


72/76


Improvement

72

Elements of ISO 9000

Management Responsibility

Quality System

Contract Review

Design Control

Document and Data Control

Purchasing

Control of Customer SuppliedProduct

Product Identification and Traceability

Process Control

Inspection and Testing

Control of Inspection,Measuring, and TestEquipment

Inspection and Test Status

Control of NonconformingProduct

Corrective and PreventiveAction

Handling, Storage,Packaging, Preservation, andDelivery

Internal Quality Audits

Training

Servicing

Statistical Techniques


73/76

Chapter 4: Six Sigma for Process

and Quality Improvement

73


74/76


Improvement

74

ISO 14000

Series of standards covering environmentalmanagement systems, environmentalauditing, evaluation of environmentalperformance, environmental labeling, andlife-cycle assessment.

Intent is to help organizations improve theirenvironmental performance throughdocumentation control, operational control,control of records, training, statisticaltechniques, and corrective and preventiveactions.


75/76

Chapter 4: Six Sigma for Process

and Quality Improvement

75


76/76

Copyright

Copyright 2006John Wiley & Sons, Inc. All rights reserved.Reproduction or translation of this work beyond that named inSection 117 of the United States Copyright Act without theexpress written consent of the copyright owner is unlawful.Requests for further information should be addressed to thePermissions Department, John Wiley & Sons, Inc. Adoptersof the textbook are granted permission to make back-upcopies for their own use only, to make copies for distributionto students of the course the textbook is used in, and tomodify this material to best suit their instructional needs.Under no circumstances can copies be made for resale. ThePublisher assumes no responsibility for errors, omissions, or

damages, caused by the use of these programs or from theuse of the information contained herein.

six sigma for process quality improvement 1233779323024526 3

Documents