7 tools for quality

Quality Improvement: Problem Solving

Week 6AgendaAgenda Review Homework

• Problems Ch 3: 2, 4 Chapter 3: Problem Solving

• Desksides: 7 QC Tools• Flow chart• Run Chart• Pareto Diagram• Histogram• Cause and Effect

Diagram• Check sheet• Scatter diagram• Control chart

Week 7 assignment • Read chapter 4• Homework

problems: Ch 3 - 11, 12, 23, 28(c)

• Case Study: "How We Slashed Response Time"


Seven Quality ToolsSeven Quality ToolsChapter 3: Problem Solving


Seven Quality Control ToolsSeven Quality Control Tools• Pareto Chart

• Histogram

• Process flow diagram• Check sheet• Scatter diagram• Control chart• Run Chart• Cause and Effect Diagram


Pareto PrinciplePareto Principle Vilfredo Pareto (1848-1923) Italian

economist• 20% of the population has 80% of the

wealth Juran used the term “vital few, trivial

many”. He noted that 20% of the quality problems caused 80% of the dollar loss.

7 Quality Tools7 Quality Tools


Pareto chartPareto chart


28

16

12 12

64 3

0

5

10

15

20

25

30

LooseThreads

Stitchingflaws

Buttonproblems

Materialflaws

% C

om

pla

ints


Pareto Pareto Chart Chart

Per

cent

fro

m e

ach

caus

e

Causes of poor quality

Mac

hine

cal

ibra

tions

Defec

tive

parts

Wro

ng d

imen

sions

Poor D

esig

n

Ope

rato

r erro

rsDef

ectiv

e m

ater

ials

Surfa

ce a

bras

ions

0

10

20

30

40

50

60

70(64)

(13)(10)

(6)(3) (2) (2)


HistogramHistogram

0

5

10

15

20

25

Category

Fre

qu

ency



HistogramHistogram

0

510152025303540

1 2 6 13 10 16 19 17 12 16 20 17 13 5 6 2 1


FlowchartsFlowcharts Flowcharts

• Graphical description of how work is done.• Used to describe processes that are to be

improved.



Flow DiagramsFlow Diagrams

" Draw a flowchart for whatever you do. Until you do, you do not know what you are doing,you just have a job.”

-- Dr. W. Edwards Deming.


FlowchartFlowchart

Activity

DecisionYesYes

NoNo



FlowchartFlowchart


Flow DiagramsFlow Diagrams


Process Chart SymbolsProcess Chart Symbols

Operations

Inspection

Transportation

Delay

Storage


Process ChartProcess ChartS

tep

Op

erat

ion

Tra

nsp

ort

Insp

ect

Del

ayS

tora

ge

Dis

tan

ce(f

eet)

Tim

e(m

in)Description

ofprocess

1

2

3

4

5

6

7

8

9

10

11

Unload apples from truck

Move to inspection station

Weigh, inspect, sort

Move to storage

Wait until needed

Move to peeler

Apples peeled and cored

Soak in water until needed

Place in conveyor

Move to mixing area

Weigh, inspect, sort

TotalPage 1 0f 3 480

30

5

20

15

360

30

20

190 ft

20 ft

20 ft

50 ft

100 ft

Date: 9-30-00

Analyst: TLR

Location: Graves Mountain

Process: Apple Sauce


Check SheetCheck SheetCheck SheetCheck Sheet

ShiftsShifts

De

fect

Typ

eD

efe

ct T

ype



Check SheetCheck Sheet

COMPONENTS REPLACED BY LABTIME PERIOD: 22 Feb to 27 Feb 1998REPAIR TECHNICIAN: Bob

TV SET MODEL 1013

Integrated Circuits ||||

Capacitors |||| |||| |||| |||| |||| ||

Resistors ||

Transformers ||||

CommandsCRT |


Cause-and-Effect DiagramsCause-and-Effect DiagramsCause-and-Effect DiagramsCause-and-Effect Diagrams Show the relationships between a

problem and its possible causes. Developed by Kaoru Ishikawa (1953) Also known as …

• Fishbone diagrams• Ishikawa diagrams



Cause and Effect Cause and Effect “Skeleton”“Skeleton”Cause and Effect Cause and Effect “Skeleton”“Skeleton”

QualityProblem

Materials

EquipmentPeople

Procedures



Fishbone Diagram Fishbone Diagram

QualityProblem

MachinesMeasurement Human

ProcessEnvironment Materials

Faulty testing equipment

Incorrect specifications

Improper methods

Poor supervision

Lack of concentration

Inadequate training

Out of adjustment

Tooling problems

Old / worn

Defective from vendor

Not to specifications

Material-handling problems

Deficienciesin product design

Ineffective qualitymanagement

Poor process design

Inaccuratetemperature control

Dust and Dirt


Cause and effect diagramsCause and effect diagrams Advantages

• making the diagram is educational in itself• diagram demonstrates knowledge of

problem solving team• diagram results in active searches for

causes• diagram is a guide for data collection


Cause and effect diagramsCause and effect diagrams

To construct the skeleton, remember: For manufacturing - the 4 M’s

man, method, machine, material For service applications

equipment, policies, procedures, people


Scatter DiagramScatter Diagram

.


Run ChartsRun Charts Run Charts (time series plot)

• Examine the behavior of a variable over time.

• Basis for Control Charts


Control ChartControl Chart

18

12

6

3

9

15

21

24

27

2 4 6 8 10 12 14 16

Sample number

Num

ber

of d

efec

ts

UCL = 23.35

LCL = 1.99

c = 12.67


Control ChartsControl Charts Control ChartsControl Charts



““Stem and leaf” displaysStem and leaf” displays

4.6 4.0 3.7 4.1 4.1 5.6 4.5 6.0 6.0 3.43.4 4.6 3.7 4.2 4.6 4.7 4.1 3.7 3.4 3.33.7 4.1 4.5 4.6 4.4 4.8 4.3 4.4 5.1 3.9

DataIntegrated Circuit Response Time (ps)


““Stem and leaf” displaysStem and leaf” displays

3 7 4 4 7 7 4 3 7 9

4 6 0 1 5 6 2 6 7 1 1 5 6 4 8 3 4

5 6 1

6 0 0

Integrated Circuit Response Time (ps)


Dot diagramsDot diagrams

3 4 5 6

Plant A

Plant B

Integrated Circuit Response Time (ps)

7 tools for quality

Documents

problem solvingcause

knowledge of problem

problem solvingdesksides

complaintsquality improvement

flowchartquality improvement

peoplequality improvement

problem solvingscatter

problem solvingcontrol