1. ENGM 621: Statistical Process Control
What is quality?

2. Meaning of Quality and Quality Improvement
TM 720: Statistical Process Control
Meaning of Quality and Quality Improvement
Quality – one of most important consumer decision factors in selecting products and services
Understanding / improving quality is key factor for success, growth, and competitive position
Substantial return on investment comes from:
Improved quality
Successful implementation of quality techniques as overall business strategy
(c) D.H. Jensen & R.C. Wurl

3. TM 720: Statistical Process Control
Dimensions of Quality
Performance – Will the product do the intended job?
Reliability – How often does the product fail?
Durability - How long does the product last?
Serviceability – How easy is it to repair the product?
Aesthetics – What does the product look like?
Features – What does the product do?
Perceived quality – What is the reputation of the company or product?
Conformance to standards – Is the product made exactly as the designer intended?
(c) D.H. Jensen & R.C. Wurl

4. Quality is a multifaceted entity.
TM 720: Statistical Process Control
Quality is a multifaceted entity.
Traditional (OLD) definition of Quality:
Fitness of use (i.e., products must meet requirements of those who use them.)
(c) D.H. Jensen & R.C. Wurl

5. Two Aspects of “Fitness for use”
TM 720: Statistical Process Control
Two Aspects of “Fitness for use”
Quality of design –
all products intentionally made in various grades of quality. (e.g., Autos differ with respect to size, options, speed, etc.)
Quality of conformance –
how well the product conforms to specifications. (e.g., If diameter of a drilled hole is within specifications then it has good quality.)
(c) D.H. Jensen & R.C. Wurl

6. What's Wrong with "Fitness for Use" Definition of Quality?
TM 720: Statistical Process Control
What's Wrong with "Fitness for Use" Definition of Quality?
Unfortunately, quality as “Fitness for Use” has become associated with the "conformance to specifications" regardless of whether or not the product is fit for use by customer.
Misconception:
Quality can be dealt with solely in manufacturing - that is, by "gold plating" the product
(c) D.H. Jensen & R.C. Wurl

7. Modern Definition of Quality:
TM 720: Statistical Process Control
Modern Definition of Quality:
Quality is inversely proportional to variability
If variability of product decreases  quality of product increases
Quality Improvement –
Reduction of variability in processes and products
Quality Engineering –
Set of operational, managerial, and engineering activities that a company uses to ensure that quality characteristics of a product are at nominal levels
(c) D.H. Jensen & R.C. Wurl

8. Statistical Methods for Quality Improvement
TM 720: Statistical Process Control
Statistical Methods for Quality Improvement
Relative Savings from a $1 investment in:
Acceptance Sampling ($1)
On-Line Process Control ($10)
Off-Line Process Improvement ($100)
(c) D.H. Jensen & R.C. Wurl

9. Quality Design & Process Variation
Lower Spec
Limit
Upper Spec
Limit
Acceptance
Sampling 60 80
100
120
140
Statistical
Process
Control
Experimental
Design

10. TM 720: Statistical Process Control
Acceptance Sampling
Reduces bad product sent to consumer
Dodge & Romig 1930s
Sample from lot to determine acceptance
More effective than 100% inspection
No feedback, prevention or improvement
(c) D.H. Jensen & R.C. Wurl

11. On-Line Process Control
TM 720: Statistical Process Control
On-Line Process Control
Monitoring of manufacturing process with control charts
Shewhart 1920s
Sample & stop process if necessary
No improvement, but maintains current process quality level
(c) D.H. Jensen & R.C. Wurl

12. TM 720: Statistical Process Control
Off-Line Improvement
Designed experiments
Taguchi & Classical Statistics 1980s
If it's not broke, improve it!
Continuous improvement of product designs and manufacturing processes
(c) D.H. Jensen & R.C. Wurl

13. Quality Myth: Higher Quality  Higher Cost
TM 720: Statistical Process Control
Quality Myth: Higher Quality  Higher Cost $
Defect Rate
Quality Cost
Total Cost
Failure
Cost
12/2/2018
ENGM 720: Statistical Process Control
(c) D.H. Jensen & R.C. Wurl

14. Very Often: Higher Quality  Lower Cost
TM 720: Statistical Process Control
Very Often: Higher Quality  Lower Cost
Gear Assembly
Manufacturing Process
$20 / part
75% Conform
100 parts
(75 good parts)
25% Non-conforming:
(10 scrap parts)
(25 parts)
Re-work Process
$4 / part
(15 good parts)
(c) D.H. Jensen & R.C. Wurl

15. TM 720: Statistical Process Control
Study finds excessive process variability responsible for high nonconformity rate
New SQC procedure implemented
NOW: manufacturing non-conformities = 5%
SAVINGS: $22.89 – $20.53 = $2.36 / good part
PRODUCTIVITY: 9% improvement
(c) D.H. Jensen & R.C. Wurl

16. How Quality Engineering Makes a Company More Competitive
TM 720: Statistical Process Control
How Quality Engineering Makes a Company More Competitive
Tactical
less inspection
less scrap and rework
more capacity
easier scheduling & shorter lead time
less inventory
less warranty cost
Strategic
more flexibility to make new products
customer satisfaction
easier to spot and solve problems
employee involvement in continuous improvement
(c) D.H. Jensen & R.C. Wurl

17. Taguchi (1980) and Robust Design
TM 720: Statistical Process Control
Taguchi (1980) and Robust Design
New Goal: consistently good performance in a variety of operating conditions
Minimize variation in processes and products
Use Designed Experiments to achieve robustness
(c) D.H. Jensen & R.C. Wurl

18. Experimental Design SCI – solder bridges, solder gaps
Squeegee over template has potential to leave too much or too little solder
SD Cement Plant \
Strength of concrete dependent of quality/amounts of raw materials that go into the product

19. Taguchi's Example: Elasticity of Caramel
TM 720: Statistical Process Control
Taguchi's Example: Elasticity of Caramel
Product X conforms to elasticity spec at 72o
Product Y performs well in a wider variety of operating conditions – more robust!
Elasticity
Prod X
Prod Y
Spec
72o
Temp
(c) D.H. Jensen & R.C. Wurl

20. Personal Example
People operate more productively at a temp of 71 degrees
69-73 degrees probably can’t tell
65 degrees we go home
75 degrees we go home

21. Total Quality Management – TQM
TM 720: Statistical Process Control
Total Quality Management – TQM
Although statistical techniques are critical for quality improvement:
the management system must direct quality improvement philosophy and ensure its implementation in all aspects of business
TQM must be implemented within a management system that is scientifically quality driven
(c) D.H. Jensen & R.C. Wurl

22. International Standards Organization ISO 9000 (1990s)
TM 720: Statistical Process Control
International Standards Organization ISO 9000 (1990s)
An ISO 9000 certified company
examined by a registered official
has an effective management system, capable of consistent performance
Examples:
System in place to correctly identify customer needs
Staff have correct versions of documentation
Preferred suppliers selected; consistent communication system
System to document and correct errors
(c) D.H. Jensen & R.C. Wurl

23. TM 720: Statistical Process Control
Six Sigma - Motorola
Six Sigma = 3.4 defects per million opportunities!
Every employee must show bottom line results of quality project – finance, mail room, manufacturing, etc.
identify problem;
develop measurement;
set goal;
close gap
Long term process – 5 years to fully implement
12/2/2018
ENGM 720: Statistical Process Control
(c) D.H. Jensen & R.C. Wurl

24. Malcolm Baldridge National Quality Award
TM 720: Statistical Process Control
Malcolm Baldridge National Quality Award
Established by congress in 1987, for excellence in organizations
Applicant receives intense investigation
NIST (National Institute of Standards and Technology) study shows Baldrige Award recipients outperformed the Standard & Poor’s 500 by nearly 2.5 to 1.
(c) D.H. Jensen & R.C. Wurl

25. TM 720: Statistical Process Control
The Baldridge Award examines quality of organization in seven categories
Leadership
Information and Analysis
Strategic Planning
Human Resource Development and Management
Process Management
Business Results
Customer Focus and Satisfaction
(c) D.H. Jensen & R.C. Wurl