Quality Tools

Quality Improvement: Problem Solving

Quality Control Tools

• Pareto chart
• Histogram
• Process flow diagram
• Check sheet
• Scatter diagram
• Control chart
• Run chart
• Cause and effect diagram
Quality Improvement: Problem Solving
Pareto Principle
‹ Vilfredo Pareto (1848-1923) Italian
economisti t
• 20% of the population has 80% of the
wealth
‹ Juran used the term “vital few, trivial
many”. He noted that 20% of the quality
many
problems caused 80% of the dollar loss.

7 Quality Tools

Quality Improvement: Problem Solving

Pareto chart
30
28
% Complaints
s

2
25

20
16
15
12 12
10
6
5 4 3
0
Loose Stitching Button Material
Threads flaws problems flaws

7 Quality Tools

Quality Improvement: Problem Solving

 70
(64)
60
Pareto

Percent from each cause

Chart
50

40

30

20
(13)
(10)
10 (6)
(3) ((2)) ((2))
0

Causes of poor quality

Quality Improvement: Problem Solving

Histogram
25

20
Frequency

15

10

0
.9
.9
.9
.9
.9
.9
9
9
9
9
9
9
9
9
9

e
1.
2.
3.
4.
5.
6.
7.
8.
9.

or
10
11
12
13
14
15
M

Category

7 Quality Tools

Quality Improvement: Problem Solving

Histogram

40
35
30
25
20
15
10
5
0 1 2 6 13 10 16 19 17 12 16 20 17 13 5 6 2 1

Quality Improvement: Problem Solving

Flowcharts
‹ Flowcharts
• Graphical description of how work is done.
• Used to describe processes that are to be
improved.

7 Quality Tools

Quality Improvement: Problem Solving

Flow Diagrams
" Draw a flowchart for whatever you do.
U til you d
Until do, you d
do nott kknow what
h t you
are doing, you just have a job.”

-- Dr. W. Edwards Deming.

Quality Improvement: Problem Solving

Flowchart
Activity

Yes
Decision

No

7 Quality Tools

Quality Improvement: Problem Solving

Flowchart

Quality Improvement: Problem Solving

Flow Diagrams

Quality Improvement: Problem Solving

Flow Diagrams

Quality Improvement: Problem Solving

Process Chart Symbols

Operations
Inspection

Transportation

Delay
y

Storage
Process Chart
Date: 9-30-00 Location: Graves Mountain
Analyst: TLR Process: Apple Sauce

Distance
Operattion
port
Description

ge
ect

et)
n)
me
ay
Storag

(min
Step
p

Tim
Transp

(fee
Inspe
Dela
of
process

1 Unload apples from truck 20

2 Move to inspection station 100 ft
3 Weigh, inspect, sort 30
4 Move to storage 50 ft
5 Wait until needed 360
6 Move to peeler 20 ft
7 Apples peeled and cored 15
8 Soak in water until needed 20
9 Place in conveyor 5
10 Move to mixing area 20 ft
11 Weigh, inspect, sort 30
Page 1 0f 3 Total 480 190 ft

Quality Improvement: Problem Solving

Quality Improvement: Problem Solving

Check Sheet

Shifts

√√√ √√√√ √ √√√

Deffect Type

√√ √√√

√√√√ √√√

√√ √

7 Quality Tools

Quality Improvement: Problem Solving

Check Sheet
COMPONENTS REPLACED BY LAB
TIME PERIOD: 22 Feb to 27 Feb 1998
REPAIR TECHNICIAN: Bob

TV SET MODEL 1013

Integrated Circuits ||||
Capacitors |||| |||| |||| |||| |||| ||
Resistors ||
Transformers ||||
Commands
CRT |

Quality Improvement: Problem Solving

Cause--and
Cause and--Effect Diagrams
‹ Show the relationships between a
problem
bl and
d itits possible
ibl causes.
‹ Developed by Kaoru Ishikawa (1953)
‹ Also known as …
• Fishbone diagrams
• Ishikawa diagrams

7 Quality Tools

Quality Improvement: Problem Solving

Cause and Effect

“Skeleton”
Materials Procedures

Quality
Problem

People Equipment
7 Quality Tools

Quality Improvement: Problem Solving

Fishbone Diagram
Measurement Human Machines

Faulty testing equipment Poor supervision Out of adjustment

Incorrect specifications Lack of concentration Tooling problems

Improper methods Inadequate training Old / worn

Quality
Inaccurate Problem
temperature Poor process
control Defective from vendor
design
Ineffective quality
p
Not to specifications management
Dust and
Dirt Material- Deficiencies
handling problems in product
design
Environment Materials Process

Quality Improvement: Problem Solving

Cause and effect diagrams

‹ Advantages
• making the diagram is educational in itself
• diagram demonstrates knowledge of
problem solving team
• diagram results in active searches for
causes
• diagram is a guide for data collection

Quality Improvement: Problem Solving

Cause and effect diagrams
To construct the skeleton,, remember:
‹ For manufacturing - the 4 M’s

9 man, method, machine, material

‹ For service applications
9 equipment,
equipment policies procedures
policies, procedures, people

Quality Improvement: Problem Solving

Scatter Diagram

Quality Improvement: Problem Solving

Run Charts
‹ Run Charts (time series plot)
• Examine the behavior of a variable over
time.
• Basis for Control Charts

Quality Improvement: Problem Solving

Control Chart 27

24
UCL = 23.35
21
Number of defects

18 c = 12.67

15

12

6
LCL = 1.99
3

2 4 6 8 10 12 14 16
Sample number
Quality Improvement: Problem Solving
Control Charts

Quality Improvement: Problem Solving

“Stem and leaf” displays

Data
Integrated Circuit Response Time (ps)

4.6 4.0 3.7 4.1 4.1 5.6 4.5 6.0 6.0 3.4
3.4 4.6 3.7 4.2 4.6 4.7 4.1 3.7 3.4 3.3
3.7 4.1 4.5 4.6 4.4 4.8 4.3 4.4 5.1 3.9

Quality Improvement: Problem Solving

“Stem and leaf” displays

Integrated Circuit Response Time (ps)

3 7 4 4 7 7 4 3 7 9

4 6 0 1 5 6 2 6 7 1 1 5 6 4 8 3 4

5 6 1

6 0 0

Quality Improvement: Problem Solving

Dot diagrams

Integrated Circuit Response Time (ps)

3 4 5 6
Plant A

Plant B

Quality Improvement: Problem Solving