5.Process Capability

One of the most important concepts in quality management is Process Capability. Rather than characterizing a process only in terms such as defects per unit or yield, we could also define it in terms of a capability".
"If the output of a process is centered around a target value, but has a wide spread of values, in other words a large standard deviation, the process is accurate but not precise".

"On the other hand, if the process has a small standard deviation (less variation) but the average value of the process parameter is far from the target, then we could say that the process is precise but not accurate"._

Process Capability Ratios Cp & Cpk

"The Cp helps us to answer the question: Are we able to produce good products?"
"The Cpk ratio helps us answer the question: Are we making good products?".

The Goal of Six Sigma

"How do we translate Sigma in terms of defects?"
The sigma scale of measure is precisely correlated to such figures as defects-per-unit, parts-per-million defectives and the probability of failure/error.

To reduce the consequences of high defect levels, world-class companies now seek process ratings of 6s i.e. 3.4 defects per million opportunities._

4.Probability and Defects

One of the most critical conceptual relationships to understand in learning the Six Sigma methodology is the idea of probability of defects and the yield of a process. The following production results were noted:

•A total of 1,000 parts were produced.
•22 parts were greater than the Upper Spec Limit.
•31 parts were less than the Lower Spec Limit.
•Therefore 22+31=53 parts were rejected._

3.Histogram and the Normal Distribution

A good way to represent a situation is to transform data into a picture; the histogram. It represents the distribution of this data.
In most of the cases, these distributions are similar to the normal distribution represented by the bell shape curve. The normal distribution makes it possible to compute, with a high degree of confidence, the probability of defects._

Shape, Location and Spread

The majority of process data will be normally distributed (Bell shape curve). If the histogram is not bell shaped, the data should be investigated further .

The term "Measures of Location" refers to the various ways in which the central tendencies of the data distribution can be calculated and displayed.

Generally, the value of the mean (average): x is the best way to estimate the central tendency of the most common distributed data.
The third important characteristic of a distribution is the spread (variation).

Generally, we estimate this variation by calculating: The range (R), or The standard deviation (s or s)._

Specification Limits

In the manufacturing environments, specifications are usually set by the Engineering functions. Operators have a clear set of limits to work to, usually set out on engineering drawings, and when the output of their process is above the Upper Specification Limit (USL), or below the Lower Specification Limit (LSL), then we say that a defect has been produced._

1.Primary Sources of Variation

Process variation, the enemy of true Six Sigma process capability, has been shown to have three main causes:

- Insufficient process capability caused by processes which produce relatively high numbers of - defective units
- Inadequate design margin, which results in unnecessarily and unreasonably tight process specifications (sometimes tighter than the customer requires)
- Unstable parts and materials, usually caused by vendors who are not able to control their own processes and ship materials which in turn yield variation in the customer's processes_

0.2 Introduction

Frequently Asked Questions About Six Sigma

What kind of return on investment(ROI) can I expect from Six Sigma training?

Average Black Belt’s projects saving vary between $50,000 and $200,000. Six Sigma Practitioner, with 100% of their time allocated to projects, can execute five or six projects during 12 months period, potentially adding an average of over $1 million to annual profits.

Why should give Six Sigma serious consideration?

The customer(especially Seagate) that form the base today’s world market are sending a clear and undeniable massage: produce a high-quality products at lower costs with greater responsiveness. To compete the world market, a company needs to move toward a Six Sigma level of performance. Many of the most profitable and admired companies in the world have set goals within a Six Sigma context, and many moving toward Six Sigma levels of performance have saved billions of dollars.

What models are used to implement Six Sigma?

There are two basic models for implementing Six Sigma.

1.Based on teaching of Six Sigma - in this model little attention, if any, is given to building an organizational infrastructure that support Six Sigma. Instead, emphasis is typically given to the mechanics of tools execution, as opposed to when and how a tool should be implemented and integrated with other tools.

2.Project based - the tools are taught and then applied to projects that are defined before sessions begin. In this model, Six Sigma infrastructure issues need to be addressed; however, this effort is sometimes not given the emphasis it deserves. Organizations can achieve more significantly bottom-line benefit with this approach.

Establishing Customer Focus

Quality Performance to the standard expected by the customer.

Definition of Quality(ISO 8402)
Totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs.
Entity(or item) : That which can be individually described and considered : process, product, and organization, a system or person or any combination thereof.

Customer Anyone internal of external to the organization who comes in contact with the product or output of my work.
There are also internal customers in a company. When an employee does work or performs a service for someone else in the company, the person who receives this work is a customer of this employee._

What is a customer satisfaction?

customer, n[O Fr. coustumier, L.L. custumarius, custom.]
1. A person who buys, especially one who buys regularly.
2. A person with whom one has to deal.

satisfaction, n[O Fr., from L. satisfaction (-onis), from satisfactus, pp. of satisfacere, to satisfy.]

1. To gratify fully the wants or desires of; to supply to the full extent.
2. To free from doubt, suspense, or uncertainly; to give full assurance to.
3. To comply with(rules or standards).

Embedded within these definition are two key ideas. First, the notion that the customer is a person, not an organization, corporation, etc........ Second, the idea that satisfaction is the extent of certainty a person(customer) has that the standard will be met._

0.1Introduction

Motorola: The Birth Place of Six Sigma


Six Sigma is a business initiative first espoused by Motorola in the early 1990s. Recently Six Sigma success stories, primary from the likes of General Electirc, Sony, and AlliedSignal, have captured the attention of Wall Street and have propagated the use of this business strategy.

The Six Sigma project executioners are sometimes called "black belts", "top guns", "change agents", "trailblazers", or "jedi" depending on the company deploying the strategy. This people are trained in the Six Sigma philosophy and methodology and are expected to accomplish at least four projects annually, which should deliver at least $1,00,000 annually to the bottom line._

Frequently Asked Questions About Six Sigma

What is Six Sigma?
The term sigma is a Greek alphabet letter (s ) used to describe variability, where a classical measurement unit consideration of the program is defects per unit.
Two major meanings in “Six Sigma”

A “Sigma quality level ” offers an indicator of how often defects are likely to occur, where the higher sigma quality level indicates a process that is less likely to create defects.
A “Six Sigma quality level ” is said to equate to 3.4 defects per million opportunities (DPMO), as described in Six Sigma Fundamental Section.

A “Six Sigma Methodology ” is a business process that allows companies to drastically improve their bottom line by designing and monitoring everyday business activities in ways that minimize waste and resources while increasing customer satisfaction.

What’s the different between Quality Control Program with Six Sigma?
Quality control program have focused on detecting and correcting commercial, industrial, and design defects but Six Sigma provides specific methods to re-create the process so that defects and errors never arise in the first place._

What is the practical difference between Three and Four Sigma Quality level?
To a first approximation, a three sigma quality level is equivalent to 1.5 misspelled words per page in a book. A six sigma quality level is equivalent to one misspelled word in all of the books in all library.

0.Introduction

World Saying About Six Sigma

“[Six Sigma] is the most important initiatives GE has ever undertaken. ” - Jack Welch,CEO, General Electric’s

“[Six Sigma] brought the $14.5 billion industrial giant back from the verge of bankruptcy by implementing the Six Sigma Breakthrough Strategy.” - Larry Bossidy, CEO, Allied Signal.

“The Six Sigma Breakthrough Strategysm offered the best way to help Seagate strengthen its competitive advantage, customer satisfaction, and bottom-line results. “- Don Colton and Don Redinius, Seagate’s executive management._

Six Sigma Meanings

A “Six Sigma Methodology ” is a business process that allows companies to drastically improve their bottom line by designing and monitoring everyday business activities in ways that minimize waste and resources while increasing customer satisfaction.

What’s the different between Quality Control Program with Six Sigma?
Quality control program have focused on detecting and correcting commercial, industrial, and design defects but Six Sigma provides specific methods to re-create the process so that defects and errors never arise in the first place._

Why is Six Sigma Succeeding Where TQM Failed?

Some of the mistake of yesterday’s TQM efforts certainly might be repeated in Six Sigma initiative if you aren’t careful. The table below provide you a TQM pitfall versus Six Sigma Solution._

TQM Pitfall

-Lack of Integration
-Leadership Apathy
-A Fuzzy Concept
-An Unclear Goal
-Purist Attitude and Technical Zealotry
-Failure to Break Down Internal Barriers
-Incremental vs. Exponential Change
-Ineffective Training
-Focus on Product Quality

Six Sigma Solution

-Link to the Business and Personal "Bottom Line"
-Leadership at the Vanguard
-A Consistently Repeated, Simple Message
-Setting a No-Nonsense, Ambitious Goal
-Adapting Tools and Degree of Rigor to the Circumstances
-Priority on Cross Functional Process Management
-Incremental Exponential Change
-Blackbelts, Greenbelts, Master Blackbelts Attention to All Business Processes