7QC Tools - Hi Tech

8/3/2019 7QC Tools - Hi Tech

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7QC Tools

Q7T/PPT- 1

7 QC TOOLS7 QC TOOLS


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Types of 7QC tools

Check Sheet

Pareto Diagram

Cause & Effect diagram

Stratification

Scatter Diagram

Graph &Control charts

Histogram

7 QC Tools

Types


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Check sheetCheck sheet

Check sheet


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What is a check sheet?

Why is a check sheet necessary?

Check sheet


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Check sheets are forms used for

standardizing

checking results of work

verifying and collecting data

Check sheet

Check sheet


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CheckSheet

MeasuredData

CountedData

PrimaryData

Point ScaleData

OrderedData

Indiscrete value such as height,weight, length, time & temp., Etc.

Discrete value such as no. Ofrecording errors, no. ofItem sold

& Rejections etc.

YES / NO or / X - Type

1st, 2nd Order Very Good, Good, No Good

- Type

1 Point, 2 Point etc.

Types of Check Sheet

Check sheet


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Below items can be added , as necessary

1. The purpose of the checks

2. The items being checked

3. The methods of the checks

4. The dates and times of the checks

5. The person to perform the checks

6. The results

Check points for check sheets preparation

Check sheet


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Defect check sheet

Check sheet

Example of check sheet

Month ,day

Component

1

2

34

5

6

7

8

9

10

4/1 2 3 4

No. ofNo. ofdefectsdefects


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Q7T/PPT- 9

You have to cut down your

house expenditure by 20% / month

How will you do it ?

Now lets do an exercise!


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Q7T/PPT- 10

BRAIN STORMING !

Brain storming


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BRAIN STORMING

Brain storming can be conducted in two ways

1. Structured

Every person in a group must give an idea as their turnarises.

Forces even shy people to participate.

Creates a certain amount of pressure to contribute.

Brain storming


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2. Unstructured

Group members simply give ideas as they come to mind. Creates more relaxed atmosphere

Risks domination.

Thumb rule : 5 15 minutes works well

Brain storming


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BRAIN STORMING

Brain storming is a technique to obtain creative ideas froma group of persons in a shortest possible time on an effect.

Brain storming plays an important role to build a cause and

effect diagram

To identify the problem - to identify the causes

To find solution - to prevent problem

Brain storming


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BRAIN STORMING SESSION

Let all the members speak freely and give ideas

Encourage wild ideas

Quantity rather than Quality ideas

Suspend judgment on Good orBad

Ride on anothers ideas

Never criticize other persons opinions

Never prohibit a person from speaking

See the problem from different angles/facets

Write down all the viewpoints

List the cause/ideas

Think of the countermeasures to eliminate the causes

Leader/facilitator need to guide the members in generating ideas

Whenever necessary non members can also be involved

Brain storming


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WHY BRAIN STORMING?

TO IDENTIFY THE PROBLEM

TO IDENTIFY CRITICAL CAUSES

TO FIND THE SOLUTION

TO PREVENT THE PROBLEM

Brain storming


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Q7T/PPT- 16

Cause & EffectCause & Effectdiagramdiagram

Cause & effect diagram


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To identify and systematically list the different causes

that can be attributed to a problem (or an effect)

To identify the reasons why a process goes out of

control

To decide which causes to investigate for process

improvement.

Why Cause & Effect ?



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What is Effect ?

EFFECT = A Result or an outcome

EFFECT is What happens



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What is cause ?

CAUSE = Reason orFactor contributing to the EFFECT

CAUSE is WHY it happens



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The analysis of

why? for what?

is cause and effect

diagram



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In 1953, Kaoru Ishikawa, Professor of theUniversity of Tokyo, used the Cause & effectdiagram for the first time.A cause & effect diagram is also called a fishbone diagram since it looks like the skeleton

of a fish.



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The EFFECT or PROBLEM is stated on the right side of

the diagram and the majorINFLUENCES or CAUSES arelisted to the left.

Main problem


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2

There are two kinds of cause & effect diagrams:

1. Cause & effect diagrams for identifying causes.

2. Cause & effect diagrams for systematically listing causes


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Cause & effect diagram for identifying the causes



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More emphasis should be given to this type of cause &effect diagram.

This is because this type of diagram is a great tool to list

ALL the causes.No effort should be made while preparing this diagram toclassify the causes. (For example under the headings ofman, machine, material etc).



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Special effort should be made to identify as many causes aspossible

The ideal method to identify as many causes as possiblewould be by brainstorming with the team members.


The classification of the causes should be taken up duringthe preparation of the second cause & effect diagram whichis specifically meant for classification of the causes.


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Remember

All the ideas/causes suggested by

members during the brainstormingsession should be noted howeverinsignificant they may initially appear.Brainstorming is a session speciallymeant for free flow of ideas.



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Effect

Causes

1



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DimensionalVariation

Poor operator skill

Machinevibration

Wrong inspection method

Wronginspectioninstrument

Improperclamping onjig or fixture

Operatorfatigue

Wrong setting of job on locator

Insufficienttraining

Too muchtightening of job

Improper material storage

No inboundinspection ofraw material Raw material

dimension tooclose to finaldimension

Improper/warped shape of raw material

Wrong spindle speed

Wrongfeed

Example

1


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Cause & effect diagram for systematically listing causes

The following steps can be followed to make a successfulCause & effect diagram for systematically listing causes

Step 1

List all the causes that have been suggested by teammembers as a part of brain storming.


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Step 3

Assign an importance to each factor, & mark the particularlyimportant factors which seem to have a significant effect.

Step 4Draw the diagram & continually look for improvement.

Step 2

Sort out the relations among the causes & connect the subcauses to the main causes. The main causes should thenbe connected to the effect.


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MACHINEMAN

MATERI

AL

METHOD

Fatigue

Dimensional

VariationLocation

JIGS & FIXTURES

STABILITY

INSPECTION

Method

Attentiveness

SPIRIT

Experience

HEALTH

SKILL

Storage

QUALITY

Inspection

ShapeFORM

Dimension

Feed

WORKING

Spindle speed

Illness Training

ConcentrationInstrument

Clamping

Imbalance

Vibration

SETTING

Degree of tightening

Placement on locator

2


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A combination of Pareto diagram & cause and effectdiagram is an ideal way to arrive at the main problem & itscauses.

Take the biggest problem from the pareto diagram & put iton the right side in the cause & effect diagram.

Derive the causes for the same.


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Whydefects?

D

People

1st Why

Plant

PoliciesProcedure

5th Why

C

3rd Why

4th Why

Thorough investigation

of causes

2nd Why


ASK WHY? 5 TIMES


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Cause Verification

4M Cause Specification Investigation Analysis

Man No focused trainingFunctionwise

trainingGeneric

No method to measure

operator's skills

Skill matrix for

each workmenNo skill matrix

No OJTPractical training

at genbaNo OJT

Workmen not trained in

specific jobs

Need based

training

Common

module given

MaterialModule content is

academic oriented

Content should bespecific need

based

Theory based

Method


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Pareto diagramPareto diagram

Pareto


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Do you remember this? (14th March 2001 - Eden gardens )

Pareto


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Do you remember this? (14th March 2001 - Eden gardens )

Pareto


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Now lets look at the second innings score board:

IndiaSS Das hit wicket b Gillespie 39

S Ramesh c ME Waugh b Warne 30

VVS Laxman c Ponting b McGrath 281

SR Tendulkarc Gilchrist b Gillespie 10SC Ganguly c Gilchrist b McGrath 48

R Dravid run out 180

N R Mongia b McGrath 4

Zaheer Khan not out 23

Harbhajan Singh not out 8

Total 657

Pareto


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When we observe which batsmen got the maximum runswe can see that Laxman & Dravid got 461 out of the 657runs. That is about 70% of the runs.

22% of the 9 batsmen who batted got 70% of the runs!

Lets now observe the Australian 2nd innings score card

Pareto


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Australia

M Hayden lbw b Tendulkar 67M Slater c Ganguly b Harbhajan 43

J Langer c Ramesh b Harbhajan 28

M Waugh lbw b Raju 0

S Waugh c Sub B Harbhajan 24R Ponting c Das b Harbhajan 0

A Gilchrist lbw b Tendulkar 0

J Gillespie c Das b Harbhajan 6

S Warne lbw b Tendulkar 0M Kasprowicz not out 13

G McGrath lbw b Harbhajan 12

Total 212

Pareto


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Who got the wickets?

O M R W

Zaheer Khan 8 4 30 0

V Prasad 3 1 7 0

Harbhajan Singh 30.3 8 73 6

V Raju 15 3 58 1

S Tendulkar 11 3 31 3

S Ganguly 1 0 2 0

Pareto

QC T l P


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When we observe which bowlers got the maximum wickets we

can see that Harbhajan & Tendulkar got 9 out of the 11wickets. That is about 80% of the wickets.

30% of the 6 bowlers who bowled got 80% of the wickets! Thisillustrates the Pareto principle

Paret

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Vilfredo Pareto was an Italian engineer in the 19th Centurywho studied the number of people in various income classes &declared

20% of the people own 80% of the countrys wealth;80% of the people own 20% of the countrys wealth

Pareto

Pareto

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Pareto Principle

Pareto principle holds good to the present day in variousapplications

A fewcauses lead to manydefects;

manycauses lead to fewdefects.

The few causes that lead to many defects are the vital few.

The many causes that lead to few defects are the trivial many.

Pareto

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Get to the biggest problems first

Solve the vital few

Pareto

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1. Collect data

2. Arrange data in the descending order

3. Calculate the relative % for individual data

4. Calculate the cumulative % for individual data

5. Draw a graph with scales on both axis

6. Draw bar chart based on data

7. Using cumulative % data, draw cumulative curve

8. Identify the VITALFEW (thumb rule > 70%)

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Pareto

Creating a Pareto Diagram

Steps

7QC Tools Pareto


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Data collection through check sheetPeriod : Week No. 45 To 50

No. Of External Phone CallsSl.No Department No. Of cells regd.

1 Production Engineering 10

2 Quality 2

3 Service 12

4 Marketing 455 Plant Maintenance 20

6 Factory production 2

7 Manufacturing Planning 1

8 Stores 5

9 Personnel 810 Materials 66

11 Finance 15

12 Research & Development 4

13 Information & Systems 6

14 Others 4

STEP 1 6645

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Sl.No Department No. Of cells reqd.

1 Materials 66

2 Marketing 45

3 Plant Maintenance 20

4 Finance 15

5 Service 12

6 Production Engineering 10

7 Personnel 8

8 Information Systems 6

9 Stores 5

10 Research & Development 4

11 Others 4

12 Quality 2

13 Factory production 2

14 Manufacturing Planning 1

200

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teria

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intenance

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Pareto

STEP 2 Arrange data in the descending orderNo. Of External Phone Calls

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Sl.No Department Nos. Relative %

1 Materials 66 33.0

2 Marketing 45 22.5

3 Plant Maintenance 20 10.0

4 Finance 15 7.5

5 Service 12 6.0

6 Production Engineering 10 5.0

7 Personnel 8 4.0

8 Information Systems 6 3.0

9 Stores 5 2.5

10 Research & Development 4 2.0

11 Others 4 2.0

12 Quality 2 1.0

13 Factory production 2 1.0

14 Manufacturing Planning 1 0.5

200

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9193.5

95.597.5 98.5

99.5 100

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teria

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intenance

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Personne

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Pareto

STEP 3 Calculate the relative % for individualNo. Of External Phone Calls

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Sl.No Department Nos. Relative % Cumulative %

1 Materials 66 33.0 33.0

2 Marketing 45 22.5 55.5

3 Plant Maintenance 20 10.0 65.5

4 Finance 15 7.5 73.0

5 Service 12 6.0 79.0

6 Production Engineering 10 5.0 84.0

7 Personnel 8 4.0 88.0

8 Information Systems 6 3.0 91.0

9 Stores 5 2.5 93.5

10 Research & Development 4 2.0 95.5

11 Others 4 2.0 97.5

12 Quality 2 1.0 98.5

13 Factory production 2 1.0 99.5

14 Manufacturing Planning 1 0.5 100.0

200 100

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55.5

65.5

73

79

8488

9193.5

95.597.5 98.5

99.5 100

0

25

50

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100

125

150

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200

Ma

teria

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Marke

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Plan

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intenance

Finance

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Eng

ineering

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Innos

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In%

Pareto

STEP 4 Calculate the cumulative % for individualData No. Of External Phone Calls

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1 Materials 66 33.0 33.0

2 Marketing 45 22.5 55.5


4 Finance 15 7.5 73.0

5 Service 12 6.0 79.0

6 Production Engineering 10 5.0 84.0

7 Personnel 8 4.0 88.0

8 Information Systems 6 3.0 91.0

9 Stores 5 2.5 93.5

10 Research & Development 4 2.0 95.5

11 Others 4 2.0 97.5

12 Quality 2 1.0 98.5

13 Factory production 2 1.0 99.5

14 Manufacturing Planning 1 0.5 100.0

200 100

TRIVIAL

MANY

VITAL FEW

Pareto

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1 Materials 66 33.0 33.0

2 Marketing 45 22.5 55.5


4 Finance 15 7.5 73.0

5 Others 60 27 100

200 100

Pareto

7QC Tools Pareto


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Pareto

66

45

2015

54

0

30

60

90

120

150

180

Materials

Marketing

PlantMaintenance

Finance

others

Dept

Inn

os

7QC Tools

Pareto


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66

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5433

55.5

65.5

73

100

0

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120

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180

Materials

Marketing

PlantMaintenance

Finance

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Cumulative%

Pareto

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Pareto

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55.5

65.5

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0

30

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Materials

Marketing

Plant

Maintenance

Finance

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Cum

ulative%

Vital

Few

70 %

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To Clearly prioritise the magnitude of the problem.

To identify the vital few and trivial many problems.

To find 80/20 rule which states that 80% of the

problems are created by 20% of the causes.

Pareto

Why pareto ?

7QC Tools Pareto


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1. The most important problem

2. The rate of each problem to the whole

3. The degree of improvement action

4. The comparison of improvement level

5. Before & after remedial action taken

Pareto

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In%Pareto diagram is used to find out

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7QC Tools

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You have to cut down your

house expenditure by 20% / month

How will you do it ?

Pareto

Same problem, but different approach

ParetParet

oo

7QC Tools Pareto


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7QC Tools

Q7T/PPT- 61

Make a check list of all the expenses

in your home & the amount youspend on these expenses

Pareto

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Sl.No Expense Amount

1 House Rent 3000

2 Electricity Bill 5003 WaterBill 280

4 Cable TV Bill 210

5 News paper bill 120

6 Milkman 300

7 Maid servant 1508 Groceries 2000

9 Entertainment & Lifestyle 1500

10 Travel 200

11 Educational 1500

12 Hospital 20013 Insurance Premium 500

14 Loan repayment 0

15 Clothes 200

16 Petrol 1300

17 Others 300

Pareto

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7QC Tools

Q7T/PPT- 63

Arrange these expenses & amounts

in an order, with the highestexpense being the first & lowest

expense being the last

Pareto

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Q

Q7T/PPT- 64

Sl.No Expense Amount

1 House rent 3000

2 Groceries 2000

3 Entertainment 1500

4 Educational 1500

5 Petrol 1300

6 Electricity bill 500

7 Insurance premium 500

8 Milkman 300

9 Others 300

10 Water bill 280

11 Cable TV 210

12 Travel 200

13 Clothes 200

14 Hospital 200

15 Maid servant 150

16 News paper 120

17 Loan repayment 0

12260

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Q

Q7T/PPT- 65

Calculate the percentage contribution of each of theseexpenses.

Percentage can be calculated by the formula

Individual expense

Total expenseX 100

7QC Tools Pareto


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Q7T/PPT- 66

Sl.No Department Nos. Relative %

1 House rent 3000 24.47

2 Groceries 2000 16.32

3 Entertainment 1500 12.23

4 Educational 1500 12.23

5 Petrol 1300 10.6

6 Electricity bill 500 4.08

7 Insurance premium 500 4.088 Milkman 300 2.45

9 Others 300 2.45

10 Water bill 280 2.28

11 Cable TV 210 1.72

12 Travel 200 1.63

13 Clothes 200 1.63

14 Hospital 200 1.63

15 Maid servant 150 1.22

16 Newspaper 120 0.98

17 Loan repayment 0 0

12260 100

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Q7T/PPT- 67


1 House rent 3000 24.47 24.47

2 Groceries 2000 16.32 40.793 Entertainment 1500 12.23 53.02

4 Educational 1500 12.23 65.25

5 Petrol 1300 10.6 75.85

6 Electricity bill 500 4.08 79.93

7 Insurance premium 500 4.08 84.01

8 Milkman 300 2.45 86.46

9 Others 300 2.45 88.91

10 Water bill 280 2.28 91.19

11 Cable TV 210 1.72 92.91

12 Travel 200 1.63 94.54

13 Clothes 200 1.63 96.1714 Hospital 200 1.63 97.8

15 Maid servant 150 1.22 99.02

16 Newspaper 120 0.98 100

17 Loan repayment 0 0 100.0

12260 100 100

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1 House rent 3000 24.47 24.47

2 Groceries 2000 16.32 40.793 Entertainment 1500 12.23 53.02

4 Educational 1500 12.23 65.25

5 Petrol 1300 10.6 75.85

6 Electricity bill 500 4.08 79.93

7 Insurance premium 500 4.08 84.01

8 Milkman 300 2.45 86.46

9 Others 300 2.45 88.91

10 Water bill 280 2.28 91.19

11 Cable TV 210 1.72 92.91

12 Travel 200 1.63 94.54

13 Clothes 200 1.63 96.1714 Hospital 200 1.63 97.8

15 Maid servant 150 1.22 99.02

16 Newspaper 120 0.98 100

17 Loan repayment 0 0 100.0

12260 100 100

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Q7T/PPT- 69

0

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HouseR

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Grocerie

s

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rtainment

Educ

atio

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Petro

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Expenses

Amount

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Cumulative%

7QC Tools Histogram


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Histogram

7QC Tools Histogram


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In quality control, we try to discover facts by collecting data &then take necessary action based on those facts.

The data is not collected as an end in itself, but as a meansof finding out the facts behind the data.

Data

FACTS

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Histogram shows a bar chart of accumulated data and

provides the easiest way to evaluate the distribution of

data .

The sizes of the vertical bars reflects the number of data

that fall into these spaces.

What is histogram ?

7QC Tools Histogram


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How to make a histogram?Let us make a histogram using an example.

Example:

To investigate the distribution of thediameters of steel shafts produced inthe grinding process, the diametersof 90 shafts are measured asshown in the table.

7QC Tools Histogram


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Sample

Number

1 - 10 2.51 2.517 2.522 2.522 2.51 2.511 2.519 2.532 2.543 2.525

11 - 20 2.527 2.536 2.506 2.541 2.512 2.515 2.521 2.536 2.529 2.524

21 - 30 2.529 2.523 2.523 2.523 2.519 2.528 2.543 2.538 2.518 2.53431 - 40 2.52 2.514 2.512 2.534 2.526 2.53 2.532 2.526 2.523 2.52

41 - 50 2.535 2.523 2.526 2.525 2.532 2.522 2.502 2.53 2.522 2.514

51 - 60 2.533 2.51 2.542 2.524 2.53 2.521 2.522 2.535 2.54 2.528

61 - 70 2.525 2.515 2.52 2.519 2.526 2.527 2.522 2.542 2.54 2.528

71 - 80 2.531 2.545 2.524 2.522 2.52 2.519 2.519 2.529 2.522 2.513

81 - 90 2.518 2.527 2.511 2.519 2.531 2.527 2.529 2.528 2.519 2.521

Results of Measurement

Diameter after grinding

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Step 1Calculate the range (R)

Obtain the largest & smallest of observed values & calculate R.

R=

(the largest observed value) (the smallest observed value)

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R = 2.545 2.502 = 0.043

Step 1

Calculate the range (R)Obtain the largest & smallest of observed values & calculate R.

R = (the largest observed value) (the smallest observed value)

7QC Tools Histogram


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Step 2

Determine the class interval & interval breadth.The class interval is calculated by the formula

Class interval = n where n is total number of observations

Here, n=

90Therefore, n = 9.48.

Rounding to nearest integer,

ClassI

nterval=

9.Interval breadth = =

= 0.005

R

n

0.043

9

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Step 3

Prepare a frequency table form

Prepare a form as shown below on which class, mid point,frequency marks, frequency etc can be recorded

Class Midpoint Frequency marks(tally)

Frequency

Total

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Step 4

Determine the class boundariesInclude so that they include the smallest & the largest ofvalues.

1. Determine the lower boundary of the first class & add

the interval breadth.Therefore, 2.5005 + interval breadth

2.5005 + 0.005 = 2.5005

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Therefore first class boundary

2.005 2.5055

The second class boundary

2.5055 2.5105

Since the class interval is 9, the last class boundary will bethe 9th. Note that this has to contain the largest recordedvalue. Therefore,

9th class boundary

2.5405 2.5455

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Step 5Calculate the mid point of the class

Sum of the upper & lower boundaries ofeach class

2

Mid point of each class =

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Step 6

Obtain the frequenciesRead the observed values one by one & record the frequencies

Falling in each class using tally marks, in groups of five asfollows:

Frequency Frequency notation

1 /

2 //

3 ///4 ////

5 ////

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Class Midpoint Frequency marks

(tally)

Frequency

1

2

34

5

6

78

9

2.5005 2.5055

2.5055 2.5105

2.5105 2.51552.5155 2.5205

2.5205 2.5255

2.5255 2.5305

2.5305 2.53552.5355 2.5405

2.5405 2.5455

2.503

2.508

2.5132.518

2.523

2.528

2.5332.538

2.543

/

////

//// //////// //// ////

//// //// //// //// //

//// //// //// ////

//// ////////

//// /

1

4

914

22

19

105

6

Total 90

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How to draw a histogram

Step 1Mark the horizontal axis with a scale. The scale need not be on the base ofthe class interval. A unit of measurement of data can be used. In thecurrent example we can take 0.01mm of diameter= 10mm on thehistogram scale. Leave a space equal to the class interval on the

horizontal axis on each side of the scale.

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Step 2Mark the left hand vertical axis with a frequency scale.

Step 3

Draw the bar chart as per the data in the frequency table.

Step 4

Draw a line on the histogram to represent the mean, & also draw a

line representing the specification limit, if any.

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0

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25

2.50 2.51 2.52 2.53 2.54 2.55

X= 2.5247

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The characteristics of the frequency distribution areshown more clearly when results are plotted in form of

block diagram

The horizontal axis is divided into segmentscorresponding to ranges of the group

On each segment a rectangle is constructed whose

height is proportional to the frequency in the group Higher bar represents more data values

Lower bar represents less data values

Overview of Histogram

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To analyze processes and discover items to be improved

To research process capability

To verify effects of an improvement To tell relative frequency of occurrence.

To easily see the distribution of the data.

To see if there is variation in the data. To make future predictions based on the data.

Application

7QC Tools Histogram


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The shape of the distribution gives a more elusive conceptthan mean or standard deviation

From the distribution we can deduce the peak value offrequency and symmetry of the data range

(i) Normal distribution

Normal distribution is commonly used

type.Here the values are symmetric

about the center

Types of distribution

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(ii) Positively skewed

Values are more concentrated in one

side nearer to origin of x line.

Here most of the values lies in thelower part of the values of histogram

(iii) Negatively skewed

Values are more concentrated in oneside far from the origin

Values lies in the higher part of thevalues of histogram

7QC Tools Stratification


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StratificationStratification



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Stratification is the act of fine tuning the data in order to

make sure of the significance of the assured factors, to the

grass root level.

Stratification



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Problem : More No. of Accidents

Let us stratify the the data regarding the accidents



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STATISTICSSTATISTICS

REPORTABLE ACCIDENTSREPORTABLE ACCIDENTS :: 0808

NONNON--REPORTABLE ACCIDENTSREPORTABLE ACCIDENTS :: 3333

NEAR MISS INCIDENTSNEAR MISS INCIDENTS :: 2121

LOST TIME INJURIESLOST TIME INJURIES :: 4141

MANDAYS LOSTMANDAYS LOST :: 187187

Rep.acct.Rep.acct. Operator not reporting back to dutyOperator not reporting back to duty

for more than 48hrsfor more than 48hrs

NonNon--reportable acct.reportable acct. Operator disablement extendingOperator disablement extending

beyond the day of shift but lessbeyond the day of shift but less

than 48 hrsthan 48 hrs

Lost time injuryLost time injury Reportable + NonReportable + Non--reportablereportable



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ANALYSISANALYSIS REPORTABLE ACCIDENTREPORTABLE ACCIDENT

Total no of reportable accident :Total no of reportable accident : 88

7QC Tools

ACCORDING TO CATEGORYACCORDING TO CATEGORY

Stratification


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ACCORDING TO CATEGORYACCORDING TO CATEGORY

Temp.workman

(3)

38%

Regular

Employee (4)

49%

Contract

Labour (1)

13%

Total no.of Reportable accidents :Total no.of Reportable accidents : 88



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ACCORDING TO PHENOMENONACCORDING TO PHENOMENON


0

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wrong assembly

Contact with chemical

Fall from Two wheeler

Fall from Height

others

Hit by objects/Fallen objects

Hit against object

Wrong handling of material handlingequipment

Adjusting/Cleaning/Loading/Unloadingwhile M/C running

No of Accidents



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ACCORDING TO BODY PARTS INJUREDACCORDING TO BODY PARTS INJURED

Finger (5)

62%Hand (1)

13%

Leg (2)

25%



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Plant-1 (0)

0%

Plant-2 (3)

37%

Plant-3 (2)

24%

R & D (1)

13%

Sp. Wh (1)

13%

Others (1)

13%

ACCORDING TO PLANTACCORDING TO PLANT




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ACCORDING TO SHIFTACCORDING TO SHIFT

4

2 2

0 00

1

2

3

4

5

I II III GEN OT

No.o

facc

iden

ts




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ACCORDING TO FAULTACCORDING TO FAULT

3

2

3

0

1

2

3

4

OPERATORS FAULT SUPERVISORY FAULT SYSTEM AND

ENVIRONMENT FAULT

No.of

acc

iden

ts




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The data has been stratified

1. According to employee category

2. According to phenomenon

3. According to body parts injured

4. According to plant

5. According to shift

6. According to fault



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Stratification over a sufficient number of units

often gives rise topatterns.

Location of these patterns often contains much

information about the causes of defects

GOAL Generation ofINFORMATION

through DATA ANALYSIS

7QC Tools Scatter diagram


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Scatter diagramScatter diagram

7QC Tools Scatter diagram Scatter diagram


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In actual practice, it is often essential to study the relation ofTWO corresponding variables.

For example,

* Relation between the dimension of a machined part onthe cutting speed of a lathe

* Relation between insert life and cutting speed



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To study the relation ofTWO variables we can use a Scatter

diagram.

KEY QUESTION How does change in one variable affect

the outcome of second variable



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The two variables we will deal with are:

a) A quality characteristic & a factor affecting it,

b) Two related quality characteristics, or

c) Two factors relating to a single quality characteristic.

Lets consider the steps in making a scatter diagram



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Example

A manufacturer of plastic tanks who made them using theblow moulding process encountered problems with defectivetanks that had thin tank walls. It was suspected that thevariation in air pressure, which varied from day to day, was thecause of the defective thin walls. The table shows data on

blowing pressure & percent defective. Let us draw a scatterdiagram using this data according to the steps givenpreviously.



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Step 1

Collect paired data (x,y) between which you want to studythe relations & arrange the data in a table. It is desirableto have at least 30 pairs of data.

7QC Tools

Data of blowing air pressure & percent defectivef l ti t k

Scatter diagram


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Date Air pressure Percent

(kgf/cm2) Defective

Oct-01 8.6 0.8892 8.9 0.8843 8.8 0.8744 8.8 0.8915 8.4 0.8746 8.7 0.8867 9.2 0.9118 8.6 0.9129 9.2 0.89510 8.7 0.89611 8.4 0.89412 8.2 0.86413 9.2 0.92214 8.7 0.90915 9.4 0.90516 8.7 0.89217 8.5 0.87718 9.2 0.88519 8.5 0.86620 8.3 0.89621 8.7 0.89622 9.3 0.92823 8.9 0.88624 8.9 0.90825 8.3 0.88126 8.7 0.88227 8.9 0.90428 8.7 0.91229 9.1 0.925

30 8.7 0.872

of plastic tank

7QC Tools

St 1

Scatter diagram


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Step 1

As seen in the table, we have 30 pairs of data.

Step 2

In this example, let blowing air pressure be indicated by X(horizontal axis), & percent defective by Y(vertical axis).

Then,

The maximum value ofX:Xmax= 9.4 (kgf/cm2)

The minimum value ofX:Xmin = 8.2 (kgf/cm2)

The maximum value ofY: Ymax= 0.928 (%)

The minimum value ofY: Ymin = 0.864 (%)



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We mark off

the horizontal axis in 0.5(kgf/cm2) intervals, from 8.0 to9.5 (kgf/cm2) and

the vertical axis in0.01(%) intervals, from 0.85 to 0.93(%)

Step 3

Plot the data.

7QC Tools

Step 4

Scatter diagram


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Step 4

Enter the time interval of the sample obtained (oct.1 oct 30) number ofsamples (n = 30), horizontal axis (blowing air pressure [kgf/cm2]), verticalaxis (percent defective [%]), and title of diagram (scatter diagram ofblowing air pressure & percent defective).

0.85

0.86

0.87

0.88

0.89

0.9

0.91

0.92

0.93

8 8.5 9 9.5

(Oct 1 Oct 30)

n=30

Blowing air pressure

7QC Tools

How to read scatter diagrams

Scatter diagram


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How to read scatter diagrams

You can grasp the correlation between pairs of data just by

looking at the shape of a scatter diagram. 5 examples aregiven below



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Series1

Positive correlation may be present Negative correlation may be present



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No correlation



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If a relation is shown between two variables,

does itNECESSARILY mean that the two

variables ARE related?

GOAL Generation ofINFORMATION through DATAANALYSIS

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