Transcript I.3 Philosophy and History - University of South Carolina

I.3 Philosophy and History
Some Goals of Manufacturing
 Various Paradigms
 Some Aspects of Taguchi’s
Philosophy

– On-Line and Off-Line Quality Control
– Design Aspects
Some Goals
The Quality Timeline
1980
1940
Design Improvements
Process Control
Quality Control
1920
Inspection
Manufacturing
Process Design
Product Design
Paradigms
The Inspection Paradigm
Process

Output
Monitor
Inspect Output To Remove
Unsatisfactory Product
Paradigms
Shewhart’s Paradigm
“Can’t Inspect Quality Into A Product”
 Detect And Correct Quality Problems By
Monitoring The Manufacturing Process
 Two Types Of Variation In A
Manufacturing Process

Variation
=
ACV
+
CCV
Paradigms
Shewhart’s Paradigm - Terminology
Shewhart: Assignable Cause Variation
(ACV) and Chance Causes Of Variation
(CCV)
 Deming: ACV=Local Faults, Special
Causes, CCV=Common Cause Variation
 Juran:
ACV=Sporadic Problems
CCV=Chronic Problems

Variation
=
ACV
+
CCV
Paradigms
Shewhart’s Paradigm
Objective
Process
Output
Monitor
Control

Monitor The Process To Detect When ACV Is
Present.
–
How Do You Detect ACV?
Control Charts
Paradigms
Shewhart’s Paradigm
Two Ways To Improve Quality
Eliminate Assignable Causes To Bring
Process Into Statistical Control
 Improve The System By Reducing
Common Cause Variation

Paradigms
Tweaking The Variation Paradigm:
The Variation/Complexity Paradigm
Variation
=
Variation
= Controllable
Variation
Complexity
of the
Process
ACV
+
CCV
Unnecessary
= Complexity
Uncontrollable
Variation
+
+
Inherent
Complexity
Paradigms
The Variation/Complexity Paradigm

Paraphrase Deming - “Reduce Variation
And Complexity And You Improve Quality”
Paradigms
Deming and Juran
Originally Found That 80 to 85% Of The
Quality Problems Required Management’s
Input In Order To Correct.
 Over The Years This Percentage Increased
To Where They Found That 94 to 96% Of
Quality Problems Were Systemic!

Paradigms
Deming And Juran’s Extension

Need Management’s Involvement
Process
Management
Output
Control
Monitor
Paradigms
Deming and Taguchi

Customer Satisfaction is the Determining
Factor in Product Design
–

Taguchi - Quality is measured in terms of loss
to society
-Wring Out the Variation
–
–
Deming and Juran - Controlling the Process
(On-Line QC)
Taguchi - Design Robust (Rugged) Processes
and Products (Off-Line QC)
Paradigms
Taguchi - Another Way To Improve Quality

Build Rugged/Robust Products And
Processes By Making Things Insensitive To
Unknown Or Uncontrollable Sources Of
Variation
Some Aspects of Taguchi’s Philosophy
Prevention Rather Than Detection

Rather Than Detecting Defects, Let’s Design Quality
Into The Product Right From The Beginning.
“An Ounce of Prevention...”
Process
Management
Customer
Output
Control
Engineering
Monitor
Some Aspects
Taguchi’s Approach

During the 50’s and 60’s Developed A
Philosophy and Methodology Concerning
Product Design and Production
Some Aspects
Design Aspects of Taguchi’s Philosophy

Robust Products And Processes Through
“Engineering Design” (Statistical Design
Of Experiments, DOE, Plays A Role Here)
–
Parameter Design

Choose Parameter (Factor) Levels To
–
–
Optimize Process or Product Performance
Mitigate Uncontrollable Factors
Some Aspects
Design Aspects of Taguchi’s Philosophy:
Factors

Control Factors
–

“Easily” controlled sources of variation
Noise
–
Uncontrollable

External - Environmental
Goal - Design Product to Be Insensitive to
Noise Factors