1. Quality Management and Control
Kahsu Mebrahtu(Asst. Prof.)
Mekelle University
College of Business and Economics
Department of Management
Postgraduate Program(MBA)
ninth edition
Chapter 3
2. What is Quality?
Quality is like beauty !!!
Meeting, or exceeding, customer
requirements now and in the future.
Quality is the totality of features and
characteristics of a product or service
that bears on its ability to satisfy given
needs.
8 - 2
3. Meaning of Quality:
Consumer’s Perspective
Fitness for use
how well product or service
does what it is supposed to
Quality of design
designing quality
characteristics into a
product or service
A Mercedes and a Ford are
equally “fit for use,” but with
different design dimensions
Copyright 2006 John Wiley & Sons, Inc. 3-3
4. Dimensions of Quality :
Manufacturing
8 - 4
QUALITY
Quality
of
Conformance
Field
Service
The
“Abilities”
Quality
of
Design
5. Quality of Design
Determined before the product is produced
Determined by market research
Translates the “wishes” of customers into
specifications
8 - 5
7. Abilities
Availability (Continuity of service to customers)
Reliability (Length of time that a product can be used
before it fails)
Maintainability (Restoration of the product or service once
it has failed)
8 - 7
8. Dimensions of Quality: Services
1. Time and Timelines: How long must a customer wait
for service and is it completed on time ?
2. Completeness: Is everything the customer asked for
provided?
3. Courtesy: How are customers treated by employees?
4. Consistency
is same level of service provided to each
customer each time?
9. Dimensions of Quality:
Service (cont.)
Accessibility and convenience
how easy is it to obtain service?
does service representative answer you calls quickly?
Accuracy
is service performed right every time?
is your bank or credit card statement correct every
month?
Responsiveness
how well does company react to unusual situations?
how well is a telephone operator at able to respond to a
customer’s questions?
Copyright 2006 John Wiley & Sons, Inc. 3-9
10. Meaning of Quality:
Producer’s Perspective
Quality of conformance
Making sure product or service is produced according
to design
if new tires do not conform to specifications, they wobble
if a hotel room is not clean when a guest checks in, hotel is
not functioning according to specifications of its design
Copyright 2006 John Wiley & Sons, Inc. 3-10
11. Meaning of Quality:
A Final Perspective
Consumer’s and producer’s perspectives
depend on each other
Consumer’s perspective: PRICE
Producer’s perspective: COST
Consumer’s view must dominate
Copyright 2006 John Wiley & Sons, Inc. 3-11
12. The Meaning of Quality
Copyright 2006 John Wiley & Sons, Inc. 3-12
Fitness for
Consumer Use
Producer’s Perspective Consumer’s Perspective
Quality of Conformance
• Conformance to
specifications
• Cost
Quality of Design
• Quality characteristics
• Price
Marketing
Production
Meaning of Quality
13. The Quality Cycle
8 - 13
MARKETING
Interprets customer needs
Works with customer to
design product to fit
operations
Interpretation of needs
CUSTOMER
Specifies quality needs
Needs
OPERATIONS
Produces the product or
services
QUALITY CONTROL
Plans and monitors
quality
Product
ENGINEERING
Defines design concept
Prepares specifications
Define quality
characteristics
Specifications
14. Total Quality Management (TQM)
Defined
Total quality management is defined as managing
the entire organization so that it excels on all
dimensions of products and services that are
important to the customer.
15. Con…
TQM represents a set of management principles that
focus on quality improvement as the driving force in all
functional areas and at all levels in a company
Principles of TQM;
1. The customer define quality, and customer satisfaction is
the top priority
2. Top management must provide the leadership for quality
3. Quality is a strategic issue and requires a strategic plan
4. Quality is the responsibility of every employee at every
level of the organization
Copyright 2006 John Wiley & Sons, Inc. 3-15
16. 5. All functions of the company must focus on continuous
quality improvement to achieve strategic goals
6 . Quality problems are solved through cooperation
among employees and management
7. Problem solving and continuous quality improvement
use statistical quality control methods
8. Training and education of all employees is the basis for
continuous quality improvement
17. Costs of Quality
External Failure
Costs
Appraisal Costs
Prevention Costs
Internal Failure
Costs
Costs of
Quality
18. Cost of Quality
Cost of Achieving Good Quality
Prevention costs
costs incurred during product design
Appraisal costs
costs of measuring, testing, and analyzing
Cost of Poor Quality
Internal failure costs
include scrap, rework, process failure, downtime, and
price reductions
External failure costs
include complaints, returns, warranty claims, liability,
and lost sales
Copyright 2006 John Wiley & Sons, Inc. 3-18
19. Prevention Costs
Quality planning costs
costs of developing and
implementing quality
management program
Product-design costs
costs of designing products
with quality characteristics
Process costs
costs expended to make sure
productive process conforms
to quality specifications
Training costs
costs of developing and
putting on quality training
programs for employees and
management
Information costs
costs of acquiring and
maintaining data related to
quality, and development of
reports on quality
performance
Copyright 2006 John Wiley & Sons, Inc. 3-19
20. Appraisal Costs
Inspection and testing
costs of testing and inspecting materials, parts, and
product at various stages and at end of process
Test equipment costs
costs of maintaining equipment used in testing
quality characteristics of products
Operator costs
costs of time spent by operators to gather data for
testing product quality, to make equipment
adjustments to maintain quality, and to stop work to
assess quality
Copyright 2006 John Wiley & Sons, Inc. 3-20
21. Internal Failure Costs
Scrap costs
costs of poor-quality products
that must be discarded,
including labor, material, and
indirect costs
Rework costs
costs of fixing defective
products to conform to quality
specifications
Process failure costs
costs of determining why
production process is
producing poor-quality
products
Process downtime costs
costs of shutting down
productive process to fix
problem
Price-downgrading costs
costs of discounting poor-
quality products—that is,
selling products as “seconds”
Copyright 2006 John Wiley & Sons, Inc. 3-21
22. External Failure Costs
Customer complaint costs
costs of investigating and
satisfactorily responding to a
customer complaint resulting
from a poor-quality product
Product return costs
costs of handling and replacing
poor-quality products returned
by customer
Warranty claims costs
costs of complying with product
warranties
Product liability costs
litigation costs resulting
from product liability
and customer injury
Lost sales costs
costs incurred because
customers are
dissatisfied with poor
quality products and do
not make additional
purchases
Copyright 2006 John Wiley & Sons, Inc. 3-22
23. Benchmarking
1. Identify those processes needing improvement.
2. Identify a firm that is the world leader in performing
the process.
3. Contact the managers of that company and make a
personal visit to interview managers and workers.
4. Analyze data.
24.
25. Designing of Quality Control Systems
Processes and “internal customers.”
“Critical points” and guidelines in identifying them.
Steps in designing QC systems.
9 -25
26. Steps in Designing QC Systems
Identify critical points
Decide on the type of measurement (variable
versus attribute)
Decide on the amount of inspection to be used.
Decide who should do the inspection
9 -26
27. Process Quality Control
Basic assumptions (tenets) of Process Quality Control:
Every process has random variation in it.
Production processes are not usually found in a state of
control.
“State of Control”; what does it mean?
9 -27
28. Process Control Chart
9 -28
x
y
Time
Upper control limit (UCL)
Center line (CL)
Lower control limit (LCL)
Average + 3
standard
deviations
Quality
measurement
average
Average - 3
standard
deviations
29. Quality Control Chart
9 -29
UCL
LCL
CL
1 2 3 4 5 6
Sample
Stop the process; look for assignable cause
Stop the process; look for assignable cause
30. Attribute: is a product characteristics such as
color, surface texture, cleanliness, or smell or taste
Hence attributes can be evaluated as: good or
bad, acceptable or not, or yes or no
A variable measure is a product characteristic
that is measured on a continuous scale such as
length h, temperature, or time
31. Types of Statistical Sampling
Attribute (Go or no-go information)
Defectives refers to the acceptability of product across a
range of characteristics.
Defects refers to the number of defects per unit which may
be higher than the number of defectives.
p-chart application
C-chart
Variable (Continuous)
Usually measured by the mean and the standard deviation.
X-bar and R chart applications
32. UCL
LCL
Samples
over time
1 2 3 4 5 6
UCL
LCL
Samples
over time
1 2 3 4 5 6
UCL
LCL
Samples
over time
1 2 3 4 5 6
Normal Behavior
Possible problem, investigate
Possible problem, investigate
Statistical Process Control
(SPC) Charts
33. Control Limits
We establish the Upper Control Limits (UCL) and the
Lower Control Limits (LCL) with plus or minus 3
standard deviations. Based on this we can expect 99.7%
of our sample observations to fall within these limits.
x
LCL UCL
99.7%
34. Control Charts for
Attributes
Copyright 2006 John Wiley & Sons, Inc. 4-34
p-charts
uses portion defective in a sample
c-charts
uses number of defects in an item
35. p-Chart
Copyright 2006 John Wiley & Sons, Inc.
UCL = p + zp
LCL = p - zp
z = number of standard deviations from
process average
p = sample proportion defective; an estimate
of process average
p = standard deviation of sample proportion
p =
p(1 - p)
n
36. Con…
p =
T otal N um b er of D efectives
T otal N um b er of O bservations
37. p-Chart Example
Copyright 2006 John Wiley & Sons, Inc. 4-37
20 samples of 100 pairs of jeans
NUMBER OF PROPORTION
SAMPLE DEFECTIVES DEFECTIVE
1 6 .06
2 0 .00
3 4 .04
: : :
: : :
20 18 .18
200
38. p-Chart Example (cont.)
Copyright 2006 John Wiley & Sons, Inc. 4-38
UCL = p + z = 0.10 + 3
p(1 - p)
n
0.10(1 - 0.10)
100
UCL = 0.190
LCL = 0.010
LCL = p - z = 0.10 - 3
p(1 - p)
n
0.10(1 - 0.10)
100
= 200 / 20(100) = 0.10
total defectives
total sample observations
p =
39. p-Chart
Example
(cont.)
Copyright 2006 John Wiley & Sons, Inc. 4-39
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Proportion
defective
Sample number
2 4 6 8 10 12 14 16 18 20
UCL = 0.190
LCL = 0.010
p = 0.10
40. c-Chart
Copyright 2006 John Wiley & Sons, Inc. 4-40
UCL = c + zc
LCL = c - zc
where
c = number of defects per sample
c = c
41. c-Chart (cont.)
Copyright 2006 John Wiley & Sons, Inc. 4-41
Number of defects in 15 sample rooms
1 12
2 8
3 16
: :
: :
15 15
190
SAMPLE
c = = 12.67
190
15
UCL = c + zc
= 12.67 + 3 12.67
= 23.35
LCL = c + zc
= 12.67 - 3 12.67
= 1.99
NUMBER
OF
DEFECTS
42. c-Chart
(cont.)
Copyright 2006 John Wiley & Sons, Inc. 4-42
3
6
9
12
15
18
21
24
Number
of
defects
Sample number
2 4 6 8 10 12 14 16
UCL = 23.35
LCL = 1.99
c = 12.67
43. Control Charts for
Variables
Copyright 2006 John Wiley & Sons, Inc. 4-43
Mean chart ( x -Chart )
uses average of a sample
Range chart ( R-Chart )
uses amount of dispersion in a
sample
44. x-bar Chart
Copyright 2006 John Wiley & Sons, Inc. 4-44
x =
x1 + x2 + ... xk
k
=
UCL = x + A2R LCL = x - A2R
= =
where
x = average of sample means
=
54. CHECK SHEETS
Used to keep a record
of the number and type
of discontinuities over a
specified period of time
or within a certain
batch of product.
PARETO CHART
A graphical representation ranking
discontinuities from the most to
least significant. Used to help
brainstorm what discontinuities, if
worked upon first, would be the
most likely to produce the greatest
improvement in quality.
Class Example
Our manufacturing procedure is composed of several steps. Several of these
procedures have lead to discontinuities noticed upon inspection. The steps causing
defectives are as follows:
Caulking 198 defectives
Fitting 25 defectives
Connections 103 defectives
Torque 18 defectives
Gapping 72 defective
A Pareto Diagram will be developed.
55.
56.
57. CAUSE AND EFFECT DIAGRAMS (Fishbone Diagram)
Used in brainstorming session to help identify the causes of quality
losses. This diagram is particularly useful after the flow chart and
the Pareto diagrams have been developed.
QUALITY
(Effect)
Cause
Step 1:Decide on the quality characteristic {e.g. Reduction of
wobble during machine rotation}
Step 2:Set up the fish bone backbone
Step 3:Identify main factors causing effect {e.g. Workers,
Materials, Inspection, Tools}
Step 4: Add Cause to each branch
58.
59. Reading Assignment
1. Acceptance Sampling
2. Kaizen method of quality management
3. Process Capability Index
4. ISO quality guidelines
5. The History of Total Quality Management