Transcript The 7 basic Quality Tools Q7

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:
can not be covered
Front bumper badly scratched on delivery, this
Performed / Checked by J
Date
2 May 2008
Example of a simple process
check sheet. (attributes)
Model XYZC217
failures
Batch
1
2
3
1
2
1
6
4
2
4
5
6
7
8
9
1
0
Power up
Boot up
1
2
Sink test
2
1
1
1
Case damage
1
1
2
Keyboard damage
Monitor damaged
1
2
Bundled s/w included
3
Checked by
pj
a
m
1
jj
[j
l
m
3
l
m
r
m
pj
a
m
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
1. Customer enquiry
received and
logged onto system
2. Enquiry briefly
overviewed and
allocated to sales
estimator for
through.
3. If it cant be done,
return to customer
Responsibility
Sales Director
Associated documents
Customers enquiry
Customers drawing
Work instruction S10
Sales Director
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.
5. Send to customer
for acceptance
6. Review quote
7. Quote is acceptable
8. Log as order and
create order
package
9. Pass to Production
control
Sales Director
Customers enquiry
Customers drawing
Previous job file
Current price list
Sales Director
Quotation
Customer
Customer
Quotation
Quotation
Quotation
Customer drawing
Work instruction S30
10. Allocated to sales
estimator
11. .
12.
Sales director
13.
14.
15.
16.
Sales Director
Order package
Etc.
Customers enquiry
Customers drawing
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
Customer
Sales director
Customer sends
enquiry
Estimator
Sales department
receives enquiry
Enquiry entered
into the electronic
Quote log &
Unique serial
number entered
Customer
informed that we
are unable to
quote
No
Can this
enquiry be
Quoted ?
Yes
Have the
item (s) been
made before?
No
Enquiry allocated
to Estimator
Raise estimate
sheet & plan
process
Quote prepared
from Price guide
Organize contract
review to cover
Quality
Contractual &
Manufacturing
aspects
Quote customer
Prepare Quote
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.
Type
Monitor
damaged
Bundled
s/w
included
Keyboard
damage
Case
damage
Sink test
Boot up
16
14
12
10
8
6
4
2
0
Power up
Quantity
Defects
100
90
80
70
60
50
40
30
20
10
0
01/02/03
02/02/03
03/02/03
04/02/03
05/02/03
06/02/03
07/02/03
08/02/03
09/02/03
10/02/03
11/02/03
12/02/03
13/02/03
14/02/03
15/02/03
16/02/03
17/02/03
18/02/03
19/02/03
20/02/03
21/02/03
22/02/03
23/02/03
24/02/03
25/02/03
26/02/03
27/02/03
28/02/03
Graphs
• This graph shows production output for
February.
Feb production output
Output %
Average
Graphs
• The graph below shows categories of customer
complaint.
Customer complaints 2007
by qty
15
20
Product quality
5
Shipped Late
Shipped early
Shipped wrong goods
60
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
Sink test
5
Case damage
4
Keyboard damage
0
Monitor damaged
3
Bundled s/w included
7
Type
Bundled
s/w
included
15
Keyboard
damage
Boot up
Sink test
4
16
14
12
10
8
6
4
2
0
Power up
Power up
Total
Quantity
Checks/only record failures
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 measurements
2
5
8
8
2
4
6
6
6
4
4
7
6
6
4
8
7
7
5
9
Histograms
Frequency
6
0
0
1
0
2
2
3
0
4
4
5
2
6
5
7
3
8
3
9
1
0
5
Frequency
Bow
4
3
2
1
0
Bow (10-3mm)
What is a Histogram?
Exercise
• 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 would
have already been collected.
Household repairs over the last 10 years
Cost £ per Total cost
Problem
frequency
occurrence £
Light bulb fails
100
0.6
60
Broken central heating
pump
1
190
190
Broken window
2
50
100
Leaking taps
16
2.5
40
Faulty central heating
boiler
1
3000
3000
Leaking radiators
3
15
45
Pareto
Pareto Chart
The data are then displayed graphically. Firstly in terms of
frequency.....
120
100
80
60
40
20
0
frequency
Fault
Broken
central
heating
Faulty
central
heating
Broken
window
Leaking
radiators
Leaking
taps
Cum %
Light
bulb fails
Occurence
House repairs 1998-2008
Pareto
... and then by cost.
House repairs 1998-2008 Total cost £
3500
3000
2500
2000
1500
1000
500
0
Total cost £
Faulty
central
heating
boiler
Broken
central
heating
pump
Broken
Light Leaking Leaking
window bulb fails radiators taps
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)
Do’s
• Give wild and
unusual ideas.
• Aim for quantity.
• Build on ideas of
others.
• Encourage
participation.
Don'ts
• Evaluate or criticise.
• Stop to soon.
• Allow domination or
idea ownership.
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.
7.
8.
9.
10.
Ideas should not be enlarged upon at this stage.
The leader is there to lead the group, not to
provide ideas.
The process is repeated until ideas dry up.
The ideas are then discussed and can be criticised
but not the people that made them.
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
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
1
6
ITEM TEAM MEMBER VOTES
NO.
1
2
3
4
5
6
TOTAL RANK
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:
Method
Man
Sub-Cause
Sub-Cause
Sub-Cause
Effect
Sub-Cause
Materials
Sub-Cause
Sub-Cause
Machines
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
Variable b
• 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
Scatter diagrams
Constructing scatter diagram
Variable b
• This process is continued, plotting different values
as one variable changes.
Variable a
Scatter diagrams
Interpreting a scatter diagram
Variable b
• The diagram below shows a Strong Positive
correlation between the variables.
Variable a
Scatter diagrams
Interpreting a scatter diagram
Variable b
• The diagram below shows a Strong Negative
correlation between the variables.
Variable a
Scatter diagrams
Interpreting a scatter diagram
Variable b
• The diagram below shows a Weak Positive
correlation.
Variable a
Scatter diagrams
Interpreting a scatter diagram
Variable b
• The diagram below shows a Weak Negative
correlation.
Variable a
Scatter diagrams
Interpreting a scatter diagram
Variable b
• The diagram below shows no correlation between
the variables.
Variable a
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
Analysis
Problem
Identification
Flow chart
Cause and
effect
Check sheet
Pareto
SPC
Brainstorming
Histogram
Scatter
Diagram
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 Okamoto
Toyota 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? Because it ran out of petrol
WHY Because he did not buy any on the way to work
?
WHY Because he had no money
?
WHY Because he lost it all in a game of poker
? Solution: Stop playing poker!!!!
Global 8D
D0
D1
D2
D3
D4
D5
D6
D7
D8
Prepare
Use the team approach
Describe the problem
Implement and verify interim containment
action
Identify and Verify root causes
Choose and Verify corrective action
Implement Corrective Action
Prevent recurrence – close the loop
Recognition