the 7 basic quality tools michele cano. agenda introductions the 7 basic tools exercises break the 7...

The 7 Basic Quality Tools

Michele Cano

Agenda

• Introductions

• The 7 Basic Tools

• Exercises

• Break

• The 7 Basic Tools continued

• Exercises

• Group Discussions

What are they?

The seven basic tools according to Ishikawa are:• Check sheets• Flow charts• Graphs & Histograms• Pareto diagram• Cause and effect diagram• Scatter diagram• Control chart

Why use tools?

• To make data visible

• Measure

• Improve

1.Check sheets

• What is a check sheet?

• A form or sheet used to record data.

Function of Check Sheets

According to Ishikawa 1982, check sheets have the following functions:

1. Production Process distribution checks

2. Defective item checks

3. Defective location checks

4. Defective cause checks

5. Check-up confirmation checks

6. Others

Example of a simple check sheet. (for car valet operation)

Car type

Car registration

Ford Focus

W357 PHR

Interior vacuumed √

Upholstery cleaned √

Dash board cleaned √

De odorised √

Body washed √

Washed waxed & Polished √

Under car washed √

Wheels washed √

Tyres blacked √

Comments: Front bumper badly scratched on delivery, this can not be covered

Performed / Checked by J Bloggs

Date 2 May 2008

Example of a simple process check sheet. (attributes)

Model XYZC217 Batch

failures 1 2 3 4 5 6 7 8 910

Power up1 2 1

Boot up6 4 2 1 2

Sink test2 1 1 1

Case damage 1 1 2

Keyboard damage

Monitor damaged 1 2

Bundled s/w included 3 1 3

Checked bypj

am jj [j lm

lm

rm pj

am pj

Flowcharts

PROCESS MAPPING

• Process mapping is an essential first step.

• It identifies all of the process activities, sequence and responsibilities.

• This can either be in a written format, or as a flowchart.

Flowcharts

PROCESS MAPPING (Written format)Enquiry handling Activity Responsibility Associated documents

1. Customer enquiry received and logged onto system

Sales Director Customers enquiry Customers drawing Work instruction S10

2. Enquiry briefly overviewed and allocated to sales estimator for through.

Sales Director

3. If it cant be done, return to customer

Sales Director Customers enquiry Customers drawing

4. If it has been made before, prepare a new quote based on previous job and current pricing, otherwise go to step 10.

Sales Director Customers enquiry Customers drawing Previous job file Current price list

5. Send to customer for acceptance

Sales Director Quotation

6. Review quote Customer Quotation 7. Quote is acceptable Customer Quotation 8. Log as order and

create order package

Quotation Customer drawing Work instruction S30

9. Pass to Production control

Sales Director Order package

10. Allocated to sales estimator

Sales director Customers enquiry Customers drawing

11. . Etc. 12.

13. 14. 15. 16.

Flowcharting

• Flowcharting is a graphical tool for analysing processes.

• Constructing flowcharts leads to a better understanding of processes.

• Better understanding of processes is a essential for improvement

Flowcharts

Some standard symbols

Start or end

An activity

a decision point in the process.

a point at which the flowchart connects with another process.

An off page connection

All records are identified

FLOWCHART

SM01 Enquiry Handling / Quotation Process

Sales director EstimatorCustomer

Customer sendsenquiry

Sales departmentreceives enquiry

Enquiry enteredinto the electronic

Quote log &Unique serial

number entered

Can thisenquiry beQuoted ?

Enquiry allocatedto Estimator

No

Quote preparedfrom Price guide

Quote customer

Customerinformed that we

are unable toquote

No

Prepare Quote

Have theitem (s) beenmade before?

Yes

Raise estimatesheet & plan

process

Organize contractreview to cover

QualityContractual &Manufacturing

aspects

HACCP

Hazard Analysis and Critical Control Points

Businesses are required to ‘identify any step in the activities of the food business which is critical to ensuring food safety and ensure that adequate safety procedures are identified, implemented, maintained, and reviewed.

Steps involved in HACCP

1. Identify the Hazard

2. Identify points when you need to have control measures (control points)

3. Decide what control measures are needed

4. Implement those controls

5. Monitor

Exercise

Draw / evaluate a flowchart for one of the following processes:

– Making a cup of coffee or tea

– Cutting the grass

– Booking a flight on-line

– Organising a surprise birthday party

3. Graphs & Histograms

Graphs, in various forms are used to aid understanding and analysis of collected data sets.

Graphs

BAR CHARTS

• This is the data set shown graphically.• It highlights the major problems for all to see.

Defects

02468

10121416

Pow

er u

p

Boo

t up

Sin

k te

st

Cas

eda

mag

e

Key

boar

dda

mag

e

Mon

itor

dam

aged

Bun

dled

s/w

incl

uded

Type

Qu

anti

ty

Graphs

• This graph shows production output for February.

0102030405060708090

100

01/0

2/03

02/0

2/03

03/0

2/03

04/0

2/03

05/0

2/03

06/0

2/03

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2/03

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2/03

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2/03

10/0

2/03

11/0

2/03

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2/03

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2/03

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2/03

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2/03

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2/03

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2/03

25/0

2/03

26/0

2/03

27/0

2/03

28/0

2/03

Output %

Average

Feb production output

Graphs

• The graph below shows categories of customer complaint.

Customer complaints 2007by qty

20

60

5

15

Product quality

Shipped Late

Shipped early

Shipped wrong goods

Rules for Graphing

• Use titles and indicate when the data was collected

• Ensure the scales are clear and represent the data accurately.

• Always keep in mind the reason why the graph is being used.

Exercise Graphs

• You are the marketing director of XZY automotive, a new Scottish company. You have organised a local survey to rate your car against other small cars.

• 30 people were polled and the results are shown below.

• Xzy, ka, Clio, Clio, ka, fiesta, xzy, ka, 206, xzy, fiesta, fiesta, xzy, polo, fiesta, 206, 206, polo, 206, fiesta, fiesta, fiesta, polo, xzy, polo, fiesta, xzy, xzy, ka, xzy.

• You have decided to Graph the results as part of your marketing drive. Choose and explain your choice of graph.

What is a Histogram?

• The Histogram shows the distribution of one characteristic for one period of time.


• Is this a histogram?

Defects

02468

10121416

Pow

er u

p

Sin

k te

st

Key

boar

dda

mag

e

Bun

dled

s/w

incl

uded

Type

Qu

anti

ty

Checks/only record failures Total

Power up 4

Boot up 15

Sink test 5

Case damage 4

Keyboard damage 0

Monitor damaged 3

Bundled s/w included 7


• The answer to the previous question is NO

• The Histogram shows the distribution of one characteristic for one period of time.

When is a Histogram Used?

• To look at one particular set of results, for one characteristic at one period of time

• To look for patterns in a process

• To help understand data

Histograms• The following data was collected when measuring

the bow (warp) of a plastic component. The specification is less than 8 x10-3 mm (zero – 8).

• This can be plotted as a histogram because we have quantitative data and target limits.

Bow measurements2 5 8 8 2

4 6 6 6 4

4 7 6 6 4

8 7 7 5 9

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7 8 9

Bow (10-3mm)F

req

ue

nc

y

HistogramsBow Frequency

0 0

1 0

2 2

3 0

4 4

5 2

6 5

7 3

8 3

9 1

0


ExerciseExercise

• Sort the data about male weights into appropriate sets, then plot a histogram.

4. Pareto Analysis

Separating the ‘vital few’ from the ‘trivial many’ Juran

What is Pareto Analysis?

• Pareto analysis is a method to help prioritise actions.

• It is a Bar Chart displayed in a particular way either in order of importance (frequency, relative cost, etc).

Pareto

Example:

The information to be represented on a Pareto diagram normally wouldhave already been collected.

Household repairs over the last 10 years

Problem frequencyCost £ per occurrence

Total cost £

Light bulb fails 100 0.6 60Broken central heating pump 1 190 190Broken window 2 50 100Leaking taps 16 2.5 40Faulty central heating boiler 1 3000 3000Leaking radiators 3 15 45

Pareto

Pareto ChartThe data are then displayed graphically. Firstly in terms of frequency.....

House repairs 1998-2008

020406080

100120

Lig

ht

bu

lb f

ails

Le

aki

ng

tap

s

Le

aki

ng

rad

iato

rs

Bro

ken

win

do

w

Bro

ken

cen

tra

lh

ea

ting

Fa

ulty

cen

tra

lh

ea

ting

Fault

Oc

cu

ren

ce

frequency

Cum %

Pareto

... and then by cost.

House repairs 1998-2008 Total cost £

0500

100015002000250030003500

Faultycentralheatingboiler

Brokencentralheatingpump

Brokenwindow

Lightbulb fails

Leakingradiators

Leakingtaps

Total cost £

Exercise

Produce a Pareto Diagram for the data in the separate handout.

6. Cause and Effect Diagrams (Ishikawa) using brainstorming

A method to help identification of the root causes of an effect (usually a

problem).

cause and effect

What is Brainstorming?

• A way to get creative ideas.

• A way to get everyone’s views.

• A way to generate alternatives.

cause and effect

Potential Uses (Brainstorming)

• For identifying areas for improvement.

• For finding potential causes of problems.

• For developing possible preventive actions.

cause and effect

Some Guidelines (Brainstorming)

• Give wild and unusual ideas.

• Aim for quantity.• Build on ideas of

others.• Encourage

participation.

• Evaluate or criticise.• Stop to soon.• Allow domination or

idea ownership.

Do’s Don'ts

Simple Rules for Brainstorming

1.Works best with a group of six to twelve members.

2. Ideas are taken from one member at a time, in rotation.

3. Ideas are written on a flip chart or OHP transparency.

4. If a response is not immediately forthcoming the member should pass.

5.No idea is too obvious or stupid.

Simple Rules for Brainstorming

6. Ideas should not be enlarged upon at this stage.

7. The leader is there to lead the group, not to provide ideas.

8. The process is repeated until ideas dry up.

9. The ideas are then discussed and can be criticised but not the people that made them.

10. Eliminate the unlikely causes and identify those with high possibilities using cause screening -

put those on a fishbone diagram.

Ranking

• Group discussion of likely causes and ease of fixing.

• Individual selection of 3-5 most likely.

• Paired comparisons

Group discussion (Ranking)

Group discusses if each possible cause is • N – Not likely• S - Somewhat likely• V - Very likely

And the ease of fixing• N - Not easy• S - Somewhat easy• V - Very easy

cause and effect

Individual Ranking

•Each person privately selects 3 - 5 items from the list

•Each person ranks their selection in order of priority

• Allocate values of 1 most important, 2 next, 3 next,

•The marks are then totalled for each item

•The item having the lowest total is then judged to have the highest priority.

Paired Comparisons

• The group preselects 6 – 8 most important causes.

• Each person completes a paired comparison grid.

• Scores are added using a vote matrix.

• Highest score is most important

No. ITEM

1 1

2

1

3

1

4

1

5

1

6

2 2

3

2

4

2

5

2

6

3 3

4

3

5

3

6

4 4

5

4

6

5 5

6

6

ITEM NO.

TEAM MEMBER VOTES TOTAL RANK

1

2

3

4

5

6

cause and effect

What is a Cause and Effect Diagram?

• The process of a cause and effect diagram consists of defining an effect in terms of possible causes and is normally carried out in the form of a Brainstorming session.

• The principal causes are typically Man, Materials, Methods or Machines. However you can also use Environment, Marketing, Management, Money etc. depending upon the exact situation.

Cause and Effect Analysis

• sub-causes can then be added

• Finally, the most likely causes are then identified for further investigation.

• These relationships are displayed pictorially in the form of a fishbone structure.

cause and effect

Layout:

Man Method

Materials Machines

Effect

Sub-Cause

Sub-Cause Sub-Cause

Sub-CauseSub-CauseSub-Cause

Using Three Cause and Effect Diagrams

1. Present situation

2. Desired final situation

3. How to get from the present to the

desired.

6. Scatter Diagrams

A method for the identification of a possible relationship between

two factors.

Scatter diagrams

What is it used for?

• Validating "hunches" about a possible cause-and-effect relationship between two variables.

• Displaying the direction of the possible relationship (positive, negative, etc.)

• Displaying the strength of the possible relationship

Scatter diagrams

Constructing scatter diagram

• In order to construct a scatter diagram you need two variables to be plotted against each other. One on the x-axis the other on the y-axis.

• Different values of variable b are then plotted against variable a.

Variable a

Var

iabl

e b

Scatter diagrams

Constructing scatter diagram

• This process is continued, plotting different values as one variable changes.

Variable a

Var

iabl

e b

Scatter diagrams

Interpreting a scatter diagram

• The diagram below shows a Strong Positive correlation between the variables.

Variable a

Var

iabl

e b

Scatter diagrams


• The diagram below shows a Strong Negative correlation between the variables.

Variable a

Var

iabl

e b

Scatter diagrams


• The diagram below shows a Weak Positive correlation.

Variable a

Var

iabl

e b

Scatter diagrams


• The diagram below shows a Weak Negative correlation.

Variable a

Var

iabl

e b

Scatter diagrams


• The diagram below shows no correlation between the variables.

Variable a

Var

iabl

e b

NOTE

• It is an important note that any positive or negative correlation does not mean that there is a cause and effect relationship between the variables.

• Only that there might be!

7. Control Charts

A method for monitoring a process for preventing defects.

Covered in a separate session by Esteban Fernandez

Problem Solving

Steps• Define Problem• Collect Data• Display Data• Analyse results• Consider possible causes• Identify possible solutions• Experiment• Implement and follow up

Problem Identification

Problem Analysis

Flow chart

Check sheet

Brainstorming

Histogram

Scatter Diagram

Cause and effect

Pareto

SPC

Problem Solving methods

• 5 Why

• Global 8D

• TRIZ

What is “5 Why”

• “5 Whys” is a problem solving technique that allows you to get at the root cause of a problem fairly quickly.

• It is used by automotive industry in Japan to determine the root cause of problems.

“Most problems do not call for complex statistical analysis but instead require painstaking, detailed problem solving

This requires a level of detailed thinking and analysis that is all too absent from most companies in day to day activity”

Yuichi OkamotoToyota technical Centre

What is 5 Why?• The “5 Why” technique is a very simple

method of getting to the root of a problem

• When a problem occurs, we ask….WHY?…until the root cause is found. Five times is usually enough to get to the root of the problem!

Advantages

• If the correct “Why” questions are asked in succession to the correct people he or she will find at least one root cause of the problem.

• It only takes short time to perform i.e. 5 to 10 mins

• There are no special tools or software required.

• It can make people have a new way of thinking out problems.

Disadvantages

• It usually only leads to one of the root causes so need to repeat the process

• Sometimes you need to go through process several times to find all the causes which can require some skill from the question maker.

• It does not always point you in the direction of generic causes e.g. training issues.

Here’s How It Works!!!• PROBLEM: Man is late for work

WHY?

Because his car stopped

WHY?

WHY?Because he did not buy any on the way to work

Because it ran out of petrol

WHY?

Because he had no money

Solution: Stop playing poker!!!!

Because he lost it all in a game of pokerWHY

?

Global 8D

D0 PrepareD1 Use the team approachD2 Describe the problemD3 Implement and verify interim containment

actionD4 Identify and Verify root causesD5 Choose and Verify corrective actionD6 Implement Corrective ActionD7 Prevent recurrence – close the loopD8 Recognition

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