Six Sigma For Process & Quality Improvement

Chapter 4 Six Sigma For Process & Quality Improvement Chapter 4: Six Sigma for Process and Quality Improvement

Quality Management and Six Sigma in Perspective
Two primary sets of costs are involved in quality:
control costs
failure costs
Costs broken into four categories:
Prevention costs
Appraisal costs
Internal costs of defects
External costs of defects
Chapter 4: Six Sigma for Process and Quality Improvement

Japanese Approaches to Quality
In 1950 the Japanese government invited W. Edwards Deming (then a professor at New York University) to give a series of lectures on quality control to help Japanese engineers reindustrialize the country.

W. Edwards Deming
Major source of poor quality is variation
Quality improvement the responsibility of top management
All employees should be trained in use of problem solving tools and especially statistical techniques

Deming’s 14 Points
1. Create constancy of purpose
2. Adopt the new philosophy
3. Cease dependence on mass inspection
4. End practice of awarding business on basis of price tags
5. Improve constantly and forever
6. Institute modern methods of training

Deming’s 14 Points continued
7. Institute modern method of supervision
8. Drive out fear
9. Breakdown organizational barriers
10. Eliminate arbitrary numerical goals
11. Eliminate work standards and quotas
12. Remove barriers that reduce pride of workmanship

Deming’s 14 Points continued
13. Institute a vigorous program of education and training
14. Push the 13 points everyday

Total Quality Management (TQM)
Better to produce item right the first time than to try to inspect quality in
Quality at the source - responsibility shifted from quality control department to workers

History of TQM
Dr. Shewart began using statistical control at the Bell Institute in 1930s
Military standards developed in 1950s
After World War II, Japanese Union of Scientist and Engineers began consulting with Deming
Deming Prize introduced in Japan in 1951

History of TQM continued
Quality assurance concept proposed in 1952
Juran makes first trip to Japan in 1954
Quality becomes Japan’s national slogan in 1956
First quality circles created in 1957
10,000 quality circles by 1966
100,000 quality circles by 1977
First U.S. quality circle 1974

Five Steps in TQM
Determine what customers want
Develop products and services
Develop production system
Monitor the system
Include customers and suppliers

Joseph Juran
Quality Control Handbook (1951)
Employees speak in different languages
Quality Trilogy
Quality Planning
Quality Control
Quality Improvement
Need to place more emphasis on planning and improvement

Joseph Juran continued
Organizations progress through four phases
Minimize prevention and appraisal costs
Appraisal costs increased
Process control introduced increasing appraisal costs but lowering internal and external failure costs
Prevention costs increased in effort to lower total quality costs

A Brief History of Six Sigma
The Six Sigma concept was developed by Bill Smith, a senior engineer at Motorola, in 1986 as a way to standardize the way defects were tallied.
Sigma is the Greek symbol used in statistics to refer to standard deviation which is a measure of variation.
Adding “six” to “sigma” combines a measure of process performance ( sigma ) with the goal of nearly perfect quality ( six ).

A Brief History of Six Sigma continued
In the popular book The Six Sigma Way, Six Sigma is defined as:
a comprehensive and flexible system for achieving, sustaining and maximizing business success. Six Sigma is uniquely driven by close understanding of customer needs, disciplined use of facts, data, and statistical analysis, and diligent attention to managing, improving, and reinventing business processes. (p. xi)

The DMAIC Improvement Process
Six Sigma projects generally follow a well defined process consisting of five phases.
d efine
m easure
a nalyze
i mprove
c ontrol
pronounced dey-MAY-ihk

The DMAIC Improvement Process Chapter 4: Six Sigma for Process and Quality Improvement

The Define Phase
The define phase of a DMAIC project focuses on clearly specifying the problem or opportunity, what the goals are for the process improvement project, and what the scope of the project is. Identifying who the customer is and their requirements is also critical given that the overarching goal for all Six Sigma projects is improving the organization’s ability to meet the needs of its customers.

Defining and Measuring Quality
Conformance to specifications
Performance
Quick response
Quick-change expertise
Features
Reliability
Durability
Serviceability
Aesthetics
Perceived quality
Humanity
Value

Benchmarking
Benchmarking involves comparing an organization's processes with the best practices to be found. Benchmarking is used for a variety of purposes, including:
Comparing an organization's processes with the best organization's processes.
Comparing an organization's products and services with those of other organizations.

Benchmarking continued
Identifying the best practices to implement.
Projecting trends in order to be able to respond proactively to future challenges and opportunities.

Quality Function Deployment (QFD)
Two key drivers of an organization’s long-term competitive success are the extent to which its new products or services meet customers’ needs, and having the organizational capabilities to develop and deliver such new products and services.
Tools for helping translate customer desires directly into product service attributes.

Four Houses of Quality
Customer requirements
Technical requirements
Component requirements
Process deployment requirements

House of Quality Details Chapter 4: Six Sigma for Process and Quality Improvement

The Measure Phase
The measure phase begins with the identification of the key process performance metrics.
Once the key process performance metrics have been specified, related process and customer data is collected.
Two commonly used process performance measures, namely, Defects per Million Opportunities (DPMO) and Process Sigma.

Defects Per Million Opportunities
Earlier it was noted that a literal interpretation of Six Sigma is 3.4 defects per million opportunities (DPMO). This may have caused some confusion for more statistically inclined readers, which we shall now attempt to reconcile.

Defects Per Million Opportunities Chapter 4: Six Sigma for Process and Quality Improvement

Process Sigma
How sigma itself can be used to measure the performance of a process.
One way to measure the performance of a process is to calculate the number of standard deviations the customer requirements are from the process mean or target value.

DPMO for Alternative Process Sigma Levels Chapter 4: Six Sigma for Process and Quality Improvement

Motorola’s Assumption the Process Mean Can Shift by as Much as 1.5 Standard Deviations Chapter 4: Six Sigma for Process and Quality Improvement

Comparison of 3 Sigma Process and 6 Sigma Process Chapter 4: Six Sigma for Process and Quality Improvement

The Analyze Phase
In this phase our objective is to utilize the data that has been collected to develop and test theories related to the root causes of existing gaps between the process’ current performance and its desired performance.
See next slide Table 4.3 Common tools and methodologies in the Six Sigma toolset.

Brainstorming
The brainstorming approach:
Do not criticize ideas during the brainstorming session.
Express all ideas no matter how radical, bizarre, unconventional, ridiculous, or impractical they may seem.
Generate as many ideas as possible.
Combine, extend, and/or improve on one another’s ideas.

Brainstorming: Actions to Enhance Team Creativity
Create diversified teams.
Use analogical reasoning.
Use brain writing.
Use the Nominal Group Technique.
Record team ideas.
Use trained facilitators to run the brainstorming session.
Set high standards.
Change the composition of the team.
Use electronic brainstorming.
Make the workplace a playground.

Cause and Effect Diagrams Chapter 4: Six Sigma for Process and Quality Improvement

Process Capability Analysis Chapter 4: Six Sigma for Process and Quality Improvement

Process Capability Analysis continued Chapter 4: Six Sigma for Process and Quality Improvement

The Improve Phase: Design of Experiments (DOE)
OFAT and 1FAT - one factor at a time.
Shortcomings
Not typically possible to test one factor at a time and hold all the other factors constant.
Not possible to account for interactions or joint variation between variables (Figure 4.16).

Design of Experiments (DOE) Chapter 4: Six Sigma for Process and Quality Improvement

DOE: continued Chapter 4: Six Sigma for Process and Quality Improvement

DOE continued
Some of the major considerations associated with DOE include:
Determining which factors to include in the experiment.
Specifying the levels for each factor.
Determining how much data to collect.
Determining the type of experimental design.

Taguchi Methods
Design for Manufacturability (DFM)
Procedure for statistical testing to determine best combination of product and transformation system design that will make output relatively independent of normal fluctuations in the production system

Statistical Quality Control Chapter 4: Six Sigma for Process and Quality Improvement

Chance Versus Assignable Variation
Chance variation is variability built into the system.
Assignable variation occurs because some element of the system or some operating condition is out of control.
Quality control seeks to identify when assignable variation is present so that corrective action can be taken.

Control Based on Attributes and Variables
Inspection for Variables: measuring a variable that can be scaled such as weight, length, temperature, and diameter.
Inspection of Attributes: determining the existence of a characteristic such as acceptable-defective, timely-late, and right-wrong.

Control Charts Chapter 4: Six Sigma for Process and Quality Improvement

Control Charts
Developed in 1920s to distinguish between chance variation in a system and variation caused by the system’s being out of control - assignable variation.

Control Charts continued
Repetitive operation will not produce exactly the same outputs.
Pattern of variability often described by normal distribution.
Random samples that fully represent the population being checked are taken.
Sample data plotted on control charts to determine if the process is still under control.

Control Chart with Limits Set at Three Standard Deviations Chapter 4: Six Sigma for Process and Quality Improvement

Control Charts for Variables Chapter 4: Six Sigma for Process and Quality Improvement

Two Control Charts
Sample Means Chart
Range Chart

Sample Data of Weights of Tacos (Ounces) Chapter 4: Six Sigma for Process and Quality Improvement

Analysis of Scenario 1 Chapter 4: Six Sigma for Process and Quality Improvement Sample means show problem having increased from 5 ounces to 8 ounces. Sample ranges have not changed from sample to sample.

Analysis of Scenario 2 Chapter 4: Six Sigma for Process and Quality Improvement Sample ranges show problem having increased from 2 ounces to 6 ounces. Sample means have not changed from sample to sample.

Patterns of Change in Process Distributions Chapter 4: Six Sigma for Process and Quality Improvement

Control Limits Chapter 4: Six Sigma for Process and Quality Improvement Sample Means Chart: Range Chart:

Calculating the Grand Mean and the Average Range Chapter 4: Six Sigma for Process and Quality Improvement

Mean Age of Ice Cream Chapter 4: Six Sigma for Process and Quality Improvement

Range in Ice Cream Age Chapter 4: Six Sigma for Process and Quality Improvement

Control Charts for Attributes Chapter 4: Six Sigma for Process and Quality Improvement

Fraction-Defective ( p ) Charts Chapter 4: Six Sigma for Process and Quality Improvement

Number-of-Defects ( c ) Charts Chapter 4: Six Sigma for Process and Quality Improvement

Six Sigma in Practice
Six Sigma Roles :
Master Black Belts.
Black Belts.
Green Belts.
Yellow Belts.
Supporting Roles:
Champions/Sponsors.
Process owners.

Quality in Services
Measuring is difficult
Training in standard procedures often used to improve quality
One way to measure quality of services is to use customer satisfaction surveys
J.D. Power and Associates uses surveys to rate domestic airlines, hotel chains, and rental car companies.

Rating the Performance of Domestic Airlines
On-time performance (25%)
Airport check-in (11%)
Courtesy of flight attendants (11%)
Seating comfort (11%)

Service Defections
Organizations should monitor customer defections
feedback from defecting customers can be used to identify problem areas
can determine what is needed to win them back
changes in defection rate can be used as early warning signal

Quality Awards/Certifications Chapter 4: Six Sigma for Process and Quality Improvement

The Malcolm Baldrige National Quality Award Chapter 4: Six Sigma for Process and Quality Improvement

ISO 9000
Guidelines for designing, manufacturing, selling, and servicing products.
Selecting an ISO 9000 certified supplier provides some assurance that supplier follows accepted business practices in areas covered by the standard

Elements of ISO 9000
Management Responsibility
Quality System
Contract Review
Design Control
Document and Data Control
Purchasing
Control of Customer Supplied Product
Product Identification and Traceability
Process Control
Inspection and Testing
Control of Inspection, Measuring, and Test Equipment
Inspection and Test Status
Control of Nonconforming Product
Corrective and Preventive Action
Handling, Storage, Packaging, Preservation, and Delivery
Internal Quality Audits
Training
Servicing
Statistical Techniques

ISO 14000
Series of standards covering environmental management systems, environmental auditing, evaluation of environmental performance, environmental labeling, and life-cycle assessment.
Intent is to help organizations improve their environmental performance through documentation control, operational control, control of records, training, statistical techniques, and corrective and preventive actions.

Copyright
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Six Sigma For Process & Quality Improvement

by Siddharth Nath

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