Quality Control Tools

Advance Quality Control
S. O. Duffuaa
Course Objectives
Enable students to model, solve and
analyze complex quality Control
Course Outcomes
Present and critique the main quality
control approaches
Formulate models for the design of
plans and implement
methods for solving these models.
Formulate models for the design of control
charts and implement methods for solving
these models.
Course Outcomes
Incorporate Taguchi approach in the design
of inspection plans and control charts.
Identify assumptions made in published
literature, relax some of them and
incorporate their effect in research papers.
Text Book and References
1. "Introduction to Statistical Quality Control" by
Douglas Montgomery, 2nd Edition, 1991, John
 "Quality Engineering in Production Systems“ by
G. Taguchi, E. Elsayed, T. Hsiang, McGraw Hill
 IIE Transactions, European Journal of
Operational Research, Journal of Quality
Technology, International Journal of Production
Research, International Journal of Quality and
Reliability Quality Management.
Course Policy
Home work
Team Discussions/presentations
Term Paper
Mid term Exam
Final Exam
Major Area and Topics
Statistical & Quality background (2)
Advances in product Control - Inspection
Plans (8)
Process Control (6)
Process Targeting (6)
Adaptive Quality Control and quality
Engineering (8)
Integrated Quality Models.
Random variables
Probability distribution
Functions of random variables
central limit theorem
Confidence estimation
Basic ideas of quality and quality
Basics of Quality
What is quality?
Fitness for purpose or use (Juran)
Conformance to requirement specifications
( Crosby)
Quality is the ability of a product or service
to consistently meet or exceed customer
expectations (Textbook and ASQ).
Basics of Quality
A product or service's nature or features
that reflect capacity to satisfy express or
implied statements of need ( Deming).
A product and service characteristics as
offered by design, marketing, manufacture,
maintenance and service that meet customer
expectations (Feigenbaum)
Quality Basics
GSA defines it as: “ Meeting the customer needs
the first time and every time”.
Boeing defines it as: “ Providing our customer
with products and services that consistently meet
the needs and the expectation”.
Federal Express Defines it as :
“ Performance to the standard expected by
Basics of Quality
Quality is not only product and services but also
include Processes, Environment and People.
Therefore a more general definition is needed
“ Quality is a dynamic state associate with products,
people, processes and environment that meets or
exceeds customer expectations”An extended
definition of quality is:
Dimensions of Quality
Performance - main characteristics of
the product/service
Aesthetics - appearance, feel, smell, taste
Special features - extra characteristics
Conformance - how well product/service
conforms to customer’s expectations
Safety - Risk of injury
Reliability - consistency of performance
Dimensions of Quality
Durability - useful life of the product/service
Perceived Quality - indirect evaluation of
quality (e.g. reputation)
Service after sale - handling of customer
complaints or checking on customer
Examples of Quality Dimensions
Table 9-1
Auto Repair
1. Performance
Everything works, fit &
Ride, handling, grade of
materials used
Interior design, soft touch
All work done, at agreed
Friendliness, courtesy,
Competency, quickness
Clean work/waiting area
2. Aesthetics
3. Special features Gauge/control placement Location, call when ready
Cellular phone, CD
Computer diagnostics
High tech
4. Safety
Antilock brakes, airbags
Separate waiting area
Examples of Quality Dimensions
Table 9-1
Dimension (Product)
Auto Repair
5. Reliability
Infrequency of breakdowns
Work done correctly,
ready when promised
6. Durability
Useful life in miles, resistance
to rust & corrosion
Work holds up over
7. Perceived
Top-rated car
Award-winning service
8. Service after Handling of complaints and/or Handling of complaints
requests for information
What is Quality
Quality of a function of many variables that
include: cost, reliability, durability,
serviceability, safety, conformance,
performance, etc …
Approaches to Quality
• Inspection
• Single
• Double
• Multiple
• Sequential
• Process Control
• Process targeting
• Quality Engineering

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