7 qc tools basic

7 QC TOOLSPRESENTED BY: Anand K Tiwari

The 7 Basic Quality Tools

Ishikawa believed that 90% of all quality problems could be solved through the use of the 7 tools listed below:

Cause and Effect (Ishikawa) DiagramsCheck SheetsHistrogramPareto diagramsFlowchartsScatter DiagramsControl Charts

What are the Basic Seven Q.C. Tools?

Cause and Effect (Ishikawa) Diagrams

-Brain StormingCheck SheetsFrequency DiagramsPareto diagramsFlowchartsScatter DiagramsControl Charts

7- QC ToolS (BASIC)

BRAIN - STORMING

Brainstorming Ideas generation

Time the session Count of ideas generated Named and anonymous ideas Each idea depicted as node of a tree Simple session

Free generation of ideas Structured session

Predefined set of questions defined as a template Generate ideas under each question

Brain Storming

Grouping Print labels in background to involve participants in

grouping of ideas

Incubation Print idea labels Print list of ideas

Clarif ication Add description to clarify the idea

Brain Storming

Preliminary Selection Mark an idea/group/sub-group as selected

depicted by a check mark (May be carried out while grouping the ideas)

Filtering and Prioritization Criteria definition Multi voting Multi criteria voting and selection Decision grid Group weightage analysis thru ideas

ranking Drivers and Barriers analysis and Final

selection of ideas

Brain Storming

FREQUENCY DIAGRAMS(Histrogram)

7- QC ToolS (BASIC)

Frequency Diagrams Process centering, spread and shape

Measurements of 50 items from process XYZ147 179 185 125 210

131 137 141 142 166

198 142 205 150 141

190 161 157 165 155

165 155 169 158 150

170 125 177 108 193

178 181 155 186 145

157 135 148 171 124

168 141 151 162 150

145 177 154 137 160

Frequency DiagramsProcess centering, spread and shape

TALLY CHARTRANGE TALLY NUMBER

100-109 | 1

110-119 0

120-129 | | | 3

130-139 | | | | 4

140-149 | | | | | | | | | 9

150-159 | | | | | | | | | | | 11

160-169 | | | | | | | | 8

170-179 | | | | | | 6

180-189 | | | 3

190-199 | | | 3

200-209 | 1

210-219 | 1

TOTAL 50

Frequency DiagramsProcess centering, spread and shape

0

2

4

6

8

10

12

100 -109

110 -119

120 -129

130 -139

140 -149

150 -159

160 -169

170 -179

180 -189

190 -199

200 -209

210 -219

Frequency


Frequency Diagram with tolerances

0

2

4

6

8

10

12

100 -109

110 -119

120 -129

130 -139

140 -149

150 -159

160 -169

170 -179

180 -189

190 -199

200 -209

210 -219

Frequency

Lo

we

r T

ole

ran

ce (

12

5)

Up

pe

r T

ole

ran

ce (

18

5)

Sp

ec.

S

pe

c.

(15

5)

(15

5)


Normal Distribution

Bi-Modal Distribution Multi-Modal Distribution

Positively Skewed Negatively Skewed

CAUSE & EFEECT

DIAGRAM

7- QC ToolS (BASIC)

Cause and Effect Analysis Ishikawa fish bone diagramming

Easy to draw like on paper

5 Why’s technique Why?… Why?…. Why?…. Why?…….. Why?

Identif ication of Root causes Mark a cause as a root cause Assign a priority number

Cause and Effect Diagrams Cause and Effect Diagrams Find and cure causes NOT symptomsFind and cure causes NOT symptoms

Possible CausesPossible CausesPROBLEMPROBLEM(EFFECT)(EFFECT)

Area AArea A Area BArea B

Area DArea DArea CArea C

11

22

3366

55

4411

22

3366

55

44

11

22

3366

55

44

11

22

3366

55

44


Bad SolderJoints

Machines Manpower

MaterialsMethods

Solder Gun

Size

Heat sink

Power Source

Skill

Training

Physical limits

Terminals

Stripping

TechniqueManual Flux

Solder

Wire Gauge


CHECK SHEETS

7- QC ToolS (BASIC)

contd…

Check Sheets and data analysis Facil i ty to design a Check sheet

Qualitative data Quantitative data with summation, averages etc.

Data Collection faci l i ty Data Analysis

Pareto chart Scatter diagrams Stratification Bar graph Line graph Pie chart

Printing of check sheet(s) and collected data

Check Sheets Counting and accumulating data

Products FaultsFault 1 Fault 2 Fault 3 Total

A | | | | | | 6B | | 2C | | | 3D | | | | | 5

Total 8 3 5 16


Process Name: Gauging/ Final Product Name: Carrier

TOTAL3/82/81/831/730/7 Defective part

61811151413TOTAL

7| | || | ||Other

2||Wire Pitted

9|| || | | ||Hole U/Size

14| | | || | || || | | |Dent, Scratch

8|| | | || |Welding Spatters

21| | | || | || | | | || | || | | |C.D.variation

Line Name: Carrier LineProduct Number: 123456


PARETO DIAGRAM

7- QC ToolS (BASIC)

Pareto Diagrams Focus on key problems

Fault No.A. DRY JOINTB. MISSED COMPONENTC. REVERSED COMPONENTD. ARCINGE. OPEN CIRCUITF. OTHER

258413

TOTAL 23

Fault No.C. REVERSED COMPONENT B. MISSED COMPONENTD. ARCINGF. OTHERA. DRY JOINTE. OPEN CIRCUIT

854321

TOTAL 23


88

REVERSEDREVERSEDCOMPONENTCOMPONENT

55

MISSED MISSED COMPONENTCOMPONENT

44

ARCINGARCING

33

OTHEROTHER22

DRY JOINTDRY JOINT 11OPEN CIRCUITOPEN CIRCUIT

BBCC DD FF AA EE


Fault No. COST TOTAL COST

C. REVERSED COMPONENT B. MISSED COMPONENTD. ARCINGF. OTHERA. DRY JOINTE. OPEN CIRCUIT

854321

225146

161020386

TOTAL 23 - 63


Fault No. COST TOTAL COST

D. ARCING C. REVERSED COMPONENT B. MISSED COMPONENT A. DRY JOINTE. OPEN CIRCUITF. OTHER

485213

522461

201610863

TOTAL 23 - 63


Rs. 20

ARCING

Rs.16

REVERSEDCOMPONENT

Rs.10

MISSED COMPONENT

Rs.8

DRY JOINT

Rs. 6

OPEN CIRCUITRs.3OTHER

CD B A E F


FLOW CHARTS

7- QC ToolS (BASIC)

Flow chart ing Drawing of a Process-chart with all standard step

symbols Facility to define a Template Form for capturing

measurement data about each step Summary report of the Process-chart Facility to draw a Process map Facility of dragging the steps of a Process-chart to a

Brainstorming session for analysis of each step under a predefined template of questions

Flowcharts Picturing the process

TerminatorUsed to Start/Stop flowchart

DataUsed to indicate datain or out of the process

ActivityUsed to show a task oractivity performed in the process.

DecisionShows the points in the process where yes/noquestions are asked

DelayUsed to indicate delaysor stock points in the process.

ConnectorUsed to link differentPoints in the flowchart.A


StartStartDoes

patient havean app’t

?

Patient arrives

Y

N

Waiting room

Appoint’t slip

Consultation

A AMake an Appointm’t

Y

N

Waitto see doctor

?

Need a follow-up

app’t?

Y

N

Need to pick up

drugs?

Fill prescrip’nat pharmacy

Patient’snotes

Patient leaves

Stop

Y

NAppoint’t

diary


SCATTER DIAGRAM

7- QC ToolS (BASIC)

Car Age (in years)

Price(in £’s)

1 2 4000

2 4 25003 1 5000

4 5 1250. . .. . .. . .

44 7 10000

10002000300040005000600070008000900010000

0 5 10

Scatter Diagrams Measuring relationships between variables

3.5

4

4.5

5

150 400 650

3.5

4

4.5

5

150 400 650

3.5

4

4.5

5

150 400 6503.5

4

4.5

5

150 400 650

3.5

4

4.5

5

150 400 650

PositivPositive Correlation

Positive Correlation?

Negative Correlation

Negative Correlation?

No CorrelationAn increasAn increase in y may dependupon an increase in x.E.g.

If X is increased, y may also increase.

If X is increased, y maydecrease.

There is no demonstrated connection between x and y.

An decrease in y may dependupon an increase in x.

Scatter Diagrams Measuring relationships between variables

CONTROL CHARTS

7- QC ToolS (BASIC)

Control Charts Recognising sources of variation

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10

Lower Control Limit (LCL)

Upper Control Limit (UCL)

Average(Xbar)


Variables dataTemperatureLengthCost

Attributes dataNumber of porous castings in a sample (defective parts)Number of cavities in a porous casting (defects)Shipping errors

Choose appropriate control chart

Attribute data:Counted and

plotted as discrete events

Variable data:Measured and plotted on a

continuous scale


Attribute Data

Defect Data Defective Data

Defect = failure to meet one of the acceptance criteria.

Defective = An entire unit fails to meet acceptance criteria.

(Defectives may have multiple defects)

Constantsample size,

usually > 5 c

c Chart

Variablesample size,

u Chart

Constantsample size,usually ≥ 50

Variablesample size,usually ≥ 50

np Chart p Chart

Fraction defectiveNumber defectiveNumber of defects Number of defectsper unit


Variable Data

Sample size= 1

X and Rm

Sample sizeis small, 2~9

Sample size islarge

usually ≥ 10

and RX and sX

Individuals and moving range

Average and standard deviation

Average and Range



Point above or below control limit.Causes: “special cause”,misread, data entry, etc.

Run 7 points increasingor decreasingCauses: maintenance, wear,environment, etc

Run of 7 points aboveor below the meanCauses:changed dist’n,new method, etc.

Erratic readingsCauses: over adjustment,measuring equipment not capable, etc

Shift in readingsCauses: change in mat’l,change in operator, etc

Cyclic readingsCauses: work pattern,Environment, etc.

GroupingFlier Shift

Trend Erratic Cycle

• Cause and Effect (Ishikawa) DiagramsCause and Effect (Ishikawa) Diagrams-Brain Storming-Brain Storming

• Check SheetsCheck Sheets• Frequency DiagramsFrequency Diagrams• Pareto diagramsPareto diagrams• FlowchartsFlowcharts• Scatter DiagramsScatter Diagrams• Control ChartsControl Charts

7- QC ToolS (BASIC)

Cause and Effect Diagram

Enables a team to focus on the content of a problem, not on the history of the problem or differing personal interests of team membersCreates a snapshot of collective knowledge and consensus of a team; builds support for solutionsFocuses the team on causes, not symptoms

Effect

Cause

Check Sheet

Creates easy-to-understand data Builds, with each observation, a clearer picture of the factsForces agreement on the definition of each condition or event of interestMakes patterns in the data become obvious quickly xx

xxxxxx x

Histogram

Displays large amounts of data that are difficult to interpret in tabular formShows centering, variation, and shapeIllustrates the underlying distribution of the dataProvides useful information for predicting future performanceHelps to answer the question “Is the process capable of meeting requirements?

Pareto Diagram

Helps a team focus on causes that have the greatest impactDisplays the relative importance of problems in a simple visual formatHelps prevent “shifting the problem” where the solution removes some causes but worsens others

Flowcharts

Shows unexpected complexity, problem areas, redundancy, unnecessary loops, and where simplification may be possibleCompares and contrasts actual versus ideal flow of a processAllows a team to reach agreement on process steps and identify activities that may impact performanceServes as a training tool

Control Chart

Focuses attention on detecting and monitoring process variation over timeDistinguishes special from common causes of variationServes as a tool for on-going controlProvides a common language for discussion process performance

* * * * *

* *

Run Chart

Monitors performance of one or more processes over time to detect trends, shifts, or cyclesAllows a team to compare performance before and after implementation of a solution to measure its impactFocuses attention on truly vital changes in the process

* * * * *

* *

Scatter Diagram

Supplies the data to confirm a hypothesis that two variables are relatedProvides both a visual and statistical means to test the strength of a relationshipProvides a good follow-up to cause and effect diagrams

* * ** * *

THANKS

7 qc tools basic

Engineering