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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
07/0
2/03
08/0
2/03
09/0
2/03
10/0
2/03
11/0
2/03
12/0
2/03
13/0
2/03
14/0
2/03
15/0
2/03
16/0
2/03
17/0
2/03
18/0
2/03
19/0
2/03
20/0
2/03
21/0
2/03
22/0
2/03
23/0
2/03
24/0
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.
What is a Histogram?
• 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
What is a Histogram?
• 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
What is a Histogram?
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
Interpreting a scatter diagram
• The diagram below shows a Strong Negative correlation between the variables.
Variable a
Var
iabl
e b
Scatter diagrams
Interpreting a scatter diagram
• The diagram below shows a Weak Positive correlation.
Variable a
Var
iabl
e b
Scatter diagrams
Interpreting a scatter diagram
• The diagram below shows a Weak Negative correlation.
Variable a
Var
iabl
e b
Scatter diagrams
Interpreting a scatter diagram
• 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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