Quality Improvement Using Six Sigma Concepts In Injection Moulding Manufacturing - Suresh Vasu -...

7/27/2019 Quality Improvement Using Six Sigma Concepts In Injection Moulding Manufacturing - Suresh Vasu - TS156.8.S98

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UNIVERSITI TEKNIKAL MALAYSIA, MELAKA

QUALITY IMPROVEMENT USING SIX SIGMA

CONCEPTS IN INJECTION MOULDINGMANUFACTURING

Thesis submitted in accordance of with the requirement of the Universiti Teknikal

Malaysia Melaka for the Degree of Bachelor of Engineering (Honours)

Manufacturing (Manufacturing Process)

By

SURESH S/O VASU

B050510019

Faculty of Manufacturing EngineeringApril 2008


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ABSTRACT

This thesis has focused on the quality improvement of major defect injection

moulding assembly line in the ALPS MALYSIA Sdn.Bhd. The objectives of this

thesis were to identify current quality problem and to improve major quality problem

in the 30 tone injection moulding operation department using Six-Sigma DMAIC

methodology. In order to analyze the data some of Statistical Quality Control (SQC)

tools were used such as pareto chart, histogram, cause and effect diagram and control

chart. The main defects in the assembly line determined and proper tool is used to

analyze the quality problem. Major defects were highlighted and analyzed. Root

causes for the problems were determined and suggestions for improvement were

suggested. After the improvement stage, suggestions for control the quality also were

suggested.


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ABSTRAK

Tesis ini bertujuan untuk memperbaiki kualiti pada produk yang di hasilkan melaui

proses injection moulding di ALPS MALAYSIA Sdn.Bhd. Objektif tesis ini

adalah, untuk mengenalpasti masalah kualiti yang dihadapi pada masa kini di

kawasan kajian dan seterusnyamemperbaiki masalah tersebut dengan menggunakan

metodologi enam-sigma(DMAIC). Untuk menganalisa data yang diperbaiki,

beberapa komponen-komponen kawalan kualiti secara statistik (SQC) seperti rajah

pareto, histogram, rajah sebeb dan akibat dan rajah kawalan. Masalah-masalah kualiti

yang wujud pada produk yang dihasilkan dikesan. Daripada masalah-masalah ini

masalah utama akan dikenalpasti dan dianalisis. Sebab-sebab utama masalah tersebut

berlaku dan cadangan untuk memperbaiki masalah tersebut akan dicadangkan.

Selepas itu, cadangan untuk mengawal kualiti pada produk siap juga akan

dicadangkan.


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CHAPTER 1INTRODUCTION

1.1 Project Background

Quality has become one of the most important competitive strategic tools which

many organizations have realized it as a key to develop products and services in

supporting continuing success. Quality system is designed to set a clear view for

organization to follow enabling understanding and involvement of employees

proceeding towards common goal.

The aim of business is long term profitability. Over a considerable length of time,

earning is achieved by pleasing customers with good products or services while

keeping production cost at a minimum. The use of quality tools and technique

provides long term dividends through lower costs and productivity improvements.

As competition increases and changes occur in the business world, one should need

to have a better understanding of quality. Quality concerns affect the entire

organization in every competitive environment. Consumer demands high quality

level of product or services at reasonable prices to achieve value and customers

satisfaction.

There is an increasing focus on quality throughout the world. With increased

competition, companies have recognized the importance of quality system

implementation in maintaining effectiveness in a volatile business environment.

Specifically meeting the needs and desired of the customers is critical and must be

done much better and efficiently than it has done in the past.


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Total Quality Management (TQM) is one of the most common quality management

practices in todays industrial environment. TQM refer to the broad set of

management and control processes designed to focus an entire organization and all of

its employees on providing products or services that do the best possible job of

satisfying the customer. According to Sashkin and Kiser (1993), TQM means that the

organizations culture is defined by, supports, the constant attainment of customer

satisfaction through an integrated system of tools, techniques, and training. This

involves the continuous improvement of organizational process, resulting in high

quality products and services.

Thus, the TQM philosophy of management is customer-focused. TQM incorporates

the concepts of product quality, process control, quality assurance, and qualityimprovement. Some advise that customer satisfaction is the driving force behind

quality improvement; other suggest quality management is achieved by internal

productivity or cost improvement programs; and still others consider TQM as mean

to introduce participatory management. In general, the Japanese concentrate on

customer satisfaction with a particular focus on understanding customer needs and

expectations.

Besides TQM there are other quality system used to improve quality such as Lean

and Six Sigma. These two are related, but distinct. Among the several quality

management concepts that have been developed, the lean concept, as in lean

manufacturing, lean production, etc. is one of the more wide-spread and successful

attempts. Briefly, lean is about controlling the resources in accordance with the

customers needs and to reduce unnecessary waste (including the waste of time). The

concept was introduced at a larger scale by Toyota in the 1950s, but not labeled lean

manufacturing until the now famous book about the automobile appeared in 1990

(Womack et al., 1990). While there are many formal definitions of the lean concept,

it is generally understood to represent a systematic approach to identifying and

eliminating elements not adding value to the process. Consequences of this are

striving for perfection and a customer-driven pull of the process.


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Meanwhile, most recent quality philosophy to be adopted by businesses around the

world is known as Six Sigma. The founder of the Six Sigma philosophy is Mikel

Harry (Harry and Schroeder, 2000). Mikel Harry developed and implemented his

Six Sigma philosophy with the Motorola Corporation and the philosophy has had

great success at the GE Corporation (Harry and Schroeder, 2000). Six sigma focuses

on the reduction and removal of variation by the application of an extensive set of

statistical tools and supporting software. This powerful business management

strategy has been exploited by many world class organizations such as General

Electric (GE), Motorola, Honeywell, Bombardier, ABB, Sony, to name a few from

the long list. Six sigma applications in the service sector are still limited although it

has been embraced by many big service oriented companies such as J P Morgan,

American Express, Lloyds TSB, Egg, City Bank, Zurich Financial Services, BT, etc.

Six sigma today has evolved from merely a measurement of quality to an overall

business improvement strategy for a large number of companies around the world.

The concept of six sigma was introduced by Bill Smith in 1986, a senior engineer

and scientist within Motorolas communication Division, in response to problems

associated with high warranty claims. The success of the efforts at Motorola was not

just achieving six sigma quality level rather the focus was on reducing defect rate in

processes through the effective utilization of powerful and practical statistical tools

and techniques. This would lead to improved productivity, improved customer

satisfaction, enhanced quality of service, reduced cost of operations or costs of poor

quality, and so on.

This thesis mainly focused on six sigma quality philosophy and other related

philosophy that would be implemented in these studies in order to identify the

current problem or rejection criteria facing by the company. The Six Sigma

philosophy used because, it provides a step-by-step quality improvement

methodology that uses statistical methods to quantify variation. An extensive on

related literature reviews was carried in order to enhance more knowledge on the

related study field.


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1.2 Problem Statement

Currently in Alps Electric Parts Production Department which produce Plastic

product for Electronic Component especially Remote Control as main businessfacing many rejection problem. The main defect cause this rejection is Black dot

on the appearance of the product. There are also some other causes that lead to

rejection such as part breakage, scratches, oily surface, white mark silver mark,

parting burr and etc. In order to study the problem a research has carried out with

help of an engineer by study the literature review on TQM, Six Sigma and PDCA

philosophies and other reference for this analysis and research method.

1.3 Objectives

The objectives of this thesis are:

To utilize six sigma methodology in performing the study.

To study the black dot rejects utilizing QC tools at the identified assembly

lines.

To identify the root causes of the black dotrejects

To recommend actions to improve the black dot rejects and sigma level.

1.4 Scope Of Project

The scope of the study is limited to part production 30 tone assembly lines only and

the analysis is focused on major defect only. Six Sigma DMAIC methodologies will

be used where DMA is applied and IC will be suggested to the company. The data

will be collected for the assembly line for six month period from May 07 to October

07.


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1.5 Report outline

Chapter 1 gives an introduction to the projects which are including objectives, scope,

and background. In this chapter, it describes the background of quality problem as

the case study of Company.

Chapter 2 presents the literature review on concepts of TQM, Six-Sigma Quality, and

what the correlation about DMAIC with other Quality Improvement approaches

(PDCA). It also presents some quality tools that incorporate with the study.

Chapter 3 describes the company background and the description of the methodology

used in this project.

Chapter 4 presents the data analysis using Six-Sigma methodology. In this chapter

the collected data from the case Study Company was analyzed stage by stage. First,

the analysis starts with Define stage, which is continued with Measurement stage and

then followed by Analyze stage. After analyze the problem based on the data

collected, and then we go to the Improve stage and culminate with Control stage.

Chapter 5 presents the conclusions of the whole project and suggestions for future

work.


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CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

Literature review includes study and research of published materials like journals,

thesis, case studies, technical documents and online library. Generally, the purpose of

a review is to analyze critically a segment of a published body of knowledge through

summary, classification and comparison of prior research studies, reviews of

literature, and theoretical articles. This chapter will describe topics that related to

quality such as Total Quality Management, Quality Management Philosophies, Six-

Sigma methodology, ISO 9000, Lean manufacturing, concept of quality, quality tools

and other relevant quality topics. Emphasizes is more on six sigma methodology

since the study conducted in a Six Sigma manner.

Besides that, this chapter also includes review on injection moulding process which

currently applied by the studied company and the types of defects that frequently

occurs in the production line.

2.2 Definitions of quality

In the Websters New World Dictionary, quality is defined as physical or

nonphysical characteristic that constitutes the basic nature of a thing or is one of its

distinguishing features.


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Shewhart (1980), mention that there are two common aspects of quality; one of these

has to do with the consideration of the quality of a thing as an objective reality

independent of the existing of man. The other has to do with what we think, feel or

sense as a result of the objective reality. This subjective side of quality is closely

linked to value. It is convenient to think of all matters related to quality of

manufactured product in terms of these three functions of specification, production

and inspection. (Grant and Leavenworth, 1988).

Quality is fitness for use, (Juran, 1989). Quality is conformance to requirements

(Crosby, 1986) and quality should be armed at the needs of the customer present and

future (Deming, 1986).

Feigenbaum (1983) said that quality is the total composite product and service

characteristics of marketing, engineering, manufacture and maintenance through

which he product and service in use will meet the expectations of the customer.

Mizuno (1988) mention that product quality encompasses those characteristics which

the product most posses if it is to be used in the intended manner. Actually, quality

can take many forms. All the definitions mentioned above can be classified into three

types. They are quality of design, quality of conformance and quality of

performance. Quality of design means that the product has been designed to

successfully fill a consumer need, real or perceived. Quality of conformance refers to

the manufacture of the product or the provision of the service that meets the specific

requirements that set by customer. Finally, quality of performance brings out the

definitions that the product or service performance its intended function as identified

by the customer.

2.3 Quality Management Philosophies

More managers than ever before are focusing on quality as a way of increasing

productivity, reducing costs, and meeting customer needs. These managers are


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beginning to understand the importance of continuously improving the quality of

their services and products as a means of achieving these goals. Those who begin to

learn about quality quickly become familiar with the names of Philip B. Crosby,

W.Edwards Deming, and Joseph M. Juran--renowned quality experts--who have

been carrying forth the message of quality for more than 30 years. At an age when

most people have retired, Philip B. Crosby and Joseph M. Juran continue an untiring

pace of work conducting seminars, consulting with clients, and writing new texts.

They have devoted their lives to helping organizations improve the quality of their

products and services. Their influence is now worldwide and their accomplishments

are legendary in the discipline.

2.3.1 The Deming Philosophy

W. Edwards Deming was originally trained as a statistician, and much of his

philosophy can be traced to these roots. He worked for Western Electric during its

pioneering era of statistical quality control development in the 1920s and 1930s.

During World War II, he taught quality control courses as part of the national

defense effort. Deming began teaching statistical quality control in Japan shortly

after Word War II a is credited with having been an important contributor to the

Japanese quality improvement programs. In fact, the highest award for quality

improvement in Japan is called the Deming Prize. While Japan embraced his

methods for 30 years, he was virtually unknown in the United States until 1980.

Deming focuses on the improvement of product and service conformance to

specifications by reducing uncertainty and variability in the design and

manufacturing process. In Deming's view, variation is the chief culprit of poor

quality. In mechanical assemblies, for example, variations from specifications for

part dimensions lead to inconsistent performance and premature wear and failure.

Likewise, inconsistencies in service frustrate customers and hurt the reputation of the

company. To achieve reduction of variation refines a never-ending cycle of product

design, manufacture, test, and sales, followed by market surveys, then redesign, and


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so forth. Deming claims that higher quality leads to higher productivity, which in

turn leads to long-term competitive advantage. The Deming "chain reaction" theory

summarizes this view; the theory states that process improvements lead to lower

costs due to less rework, fewer mistakes, delays and snags, and more efficient use of

materials. Lower costs, in turn, lead to productivity improvements. With better

quality and lower prices, the firm can achieve a greater or larger market share and

remain competitive and provide more meaningful and rewarding jobs. Upper

management needs to recognize the benefits of quality as a strategic factor and strive

to create a culture that supports empowerment, continuous improvement and

customer satisfactions. Deming stresses that top management has the overriding

responsibility for quality improvement (Deming, 1986)

2.3.1.1 Deming's 14 Points for Management

1. Create and publish to all employees a statement of the aims and

purposes of the company or other organization. Management must

demonstrate constantly their commitment to this statement

2. Learn the new philosophy throughout all areas everybody.

3. Understand the purpose of inspection. It should evaluate process

improvements and cost reductions.

4. End the practice of awarding business on the basis of price alone

5. Improve constantly and forever the system of production and service

6. Institute training

7. Teach and institute leadership

8. Drive out fear. Create trust. Create a climate for innovation

9. Optimize all efforts toward the aims and purposes of the company.

10. Eliminate exhortations for the work force

11. (a) Eliminate numerical quotas for production Instead learn and institute

methods for improvement

(b) Eliminate management by objectives (MBO). Instead, learn the

capabilities of processes, and how to improve them.


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12. Remove barriers that rob people of pride of workmanship.

13. Encourage education and self-improvement for everyone.

14. Take action to accomplish the transformation

2.3.2 Jurans Quality Trilogy

Dr. J. M. Juran, whose impact on the quality movement in Japan, was second only to

Demings, developed a useful framework to what referred to as "a universal thought

process-a universal way of thinking about quality, which fits all functions all levels,

all product lines. He called it the "quality trilogy: The underlying concept of the

quality trilogy is that managing for quality consists of three basic quality orientedprocesses:

Quality planning

Quality control

Quality improvement

The starting point is quality planning which involves creating a process that will be

able to established goals. Once the process is turned over to the operating forces,

their responsibility is to run the process at optimal effectiveness and take corrective

action when the process or product does not conform to established specifications.

Finally, quality improvement is "the process for breaking through to unprecedented

levels of performance. But quality improvement does not happen of its own accord.

It results from purposeful action taken by upper management to introduce a new

managerial approach throughout the organization of quality improvement process.

This quality improvement process is super-imposed on the quality control process. It

is implemented in addition to quality control, not instead of it. Juran's approach is

essentially the same as Demings. Quality is a management responsibility that needs

to be performed systematically to achieve continuous improvement over time.


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This is the same basic idea behind the so-called PDCA cycle, known in Japan as the

Deming wheel, which is considered to be the essence of the Japanese approach to

total quality control:

Plan: The basic planning process described by Juran.

Do: The implementation of the plan.

Check: Evaluation of performance according to critical measures appropriate

methods

Act: Quality improvement efforts based on the lessons learned from

experiences. These experiences feed into the new plan, since PDCA is a

cyclical process (Costin, 1994)

2.3.3 The Crosby philosophy

Philip B. Crosby was corporate vice president for quality at International Telephone

and Telegraph (ITT) for 14 years after working his way up from line inspector. After

that he e established Philip Crosby Associates in 1979 to develop and offer training

programs related to quality. He is also the author of several popular books. His first

book, Quality is Free published in 1979, sold about one million copies.

The essence of Crosby's quality philosophy is embodied in what he calls the

"Absolutes of' Quality Management and the Basic Elements of Improvement."

Crosby's Absolutes of Quality Management areas follow:

Quality means conformance to requirement, not elegance

There is no such thing as quality problem only opportunities to improve.

There is no such thing as the economics of quality; it always cheaper to

do the job right the first time.

The only performance measurement is the cost of quality approach.

The only performance standard is Zero Defect


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Crosby's Basic Elements of Improvement include determination, education, and

implementation. By determination, Crosby means that top management must be

serious about quality improvement. The Absolutes should be understood by

everyone; this can be accomplished only through education. Finally, every member

of the management team must understand the implementation process. (Evans &

Lindsay,1993).

2.4 Introduction and Implementation of Total Quality Management

(TQM)

Total Quality Management is a management approach that originated in the 1950's

and has steadily become more popular since the early 1980's. Total Quality is a

description of the culture, attitude and organization of a company that strives to

provide customers with products and services that satisfy their needs. The culture

requires quality in all aspects of the company's operations, with processes being done

right the first time and defects and waste eradicated from operations.

Total Quality Management, TQM, is a method by which management and employees

can become involved in the continuous improvement of the production of goods and

services. It is a combination of quality and management tools aimed at increasing

business and reducing losses due to wasteful practices. Some of the companies who

have implemented TQM include Ford Motor Company, Phillips Semiconductor,

SGL Carbon, Motorola and Toyota Motor Company (Gilbert, 1992).

2.4.1 TQM Definination

TQM is a management philosophy that seeks to integrate all organizational functions

such as marketing, finance, design, engineering, and production, customer service,

etc. to focus on meeting customer needs and organizational objectives.


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TQM views an organization as a collection of processes. It maintains that

organizations must strive to continuously improve these processes by incorporating

the knowledge and experiences of workers. The simple objective of TQM is "Do the

right things, right the first time, every time". TQM is infinitely variable and

adaptable.

Although originally applied to manufacturing operations, and for a number of years

only used in that area, TQM is now becoming recognized as a generic management

tool, just as applicable in service and public sector organizations. There are a number

of evolutionary strands, with different sectors creating their own versions from the

common ancestor.

TQM is the foundation for activities, which include commitment by senior

management and all employees, meeting customer requirements, reducing

development cycle times, Just In Time/ Demand flow manufacturing and

improvement teams. This shows that all personnel, in Manufacturing, Marketing,

Engineering, R&D, Sales, Purchasing, HR, etc must practice TQM in all activities.

(Hyde,1992).

2.4.2 Implementation Principles and Processes of TQM

A preliminary step in TQM implementation is to assess the organization's current

conditions. Relevant preconditions have to do with the organization's history, its

current needs, precipitating events leading to TQM, and the existing employee

quality of working life. If the current reality does not include important

preconditions, TQM implementation should be delayed until the organization is in a

state in which TQM is likely to succeed.

If an organization has a track record of effective responsiveness to the environment,

and if it has been able to successfully change the way it operates when needed, TQM

will be easier to implement. If an organization has been historically reactive and has


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little skill at improving its operating systems, there will be both employee skepticism

and a lack of skilled change agents. If this condition prevails, a comprehensive

program of management and leadership development may be instituted. A

management audit is a good assessment tool to identify current levels of

organizational functioning and areas in need of change. An organization should be

basically healthy before beginning TQM. If it has significant problems such as a very

unstable funding base, weak administrative systems, lack of managerial skill, or poor

employee morale, TQM would not be appropriate (Tichey, 1993).

However, a certain level of stress is probably desirable to initiate TQM. People need

to feel a need for a change. Kanter (1983) addresses this phenomenon as building

blocks, which are present in effective organizational change. These forces includedepartures from tradition, a crisis or galvanizing event, strategic decisions, individual

"prime movers," and action vehicles. Departures from tradition are activities, usually

at lower levels of the organization, which occur when entrepreneurs move outside the

normal ways of operating to solve a problem. A crisis, if it is not too disabling, can

also help create a sense of urgency, which can mobilize people to act. In the case of

TQM, this may be a funding cut or threat, or demands from consumers or other

stakeholders for improved quality of service. After a crisis, a leader may intervene

strategically by articulating a new vision of the future to help the organization deal

with it. A plan to implement TQM may be such a strategic decision. Such a leader

may then become a prime mover, who takes charge in championing the new idea and

showing others how it will help them get where they want to go. Finally, action

vehicles are needed and mechanisms or structures to enable the change to occur and

become institutionalized (Smith, 1999).

2.4.3 Summary for TQM

TQM encourages participation amongst shop floor workers and managers. There is

no single theoretical formalization of total quality, but Deming, Juran and Ishikawa

provide the core assumptions, as a:


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"...discipline and philosophy of management which institutionalizes planned and

continuous improvement ... and assumes that quality is the outcome of all activities

that take place within an organization; that all functions and all employees have to

participate in the improvement process; that organizations need both quality systems

and a quality culture."

2.5 Six-Sigma Quality

Six-Sigma refers to the philosophy and methods companies such as General Electric

and Motorola use to eliminate defects in their products and processes. A defect is

simply any component that does not fall within the customers specification limits.

Each step or activity in a company represents an opportunity for defects to occur and

Six-Sigma programs seek to reduce the variation in the processes that lead to these

defects. Indeed, Six-Sigma advocates see variation as the enemy of quality and much

of the theory underlying Six-Sigma is devoted to dealing with this problem. A

process that is in Six-Sigma control will produce no more than 3.4 defects out of

every million units.

One of the benefits of Six-Sigma thinking is that it allows managers to readily

describe the performance of a process in terms of its variability and to compare

different processes using a common metric. This metric is defects per million

opportunities (DPMO). (Raisinghani,M.S 2005).This calculation requires three

pieces of data:

Unit: The item produced or being serviced.

Defect: Any item or event that does not meet the customers

requirements.

Opportunity: A chance for a defect to occur.

A straightforward calculation is made using the following formula:


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2.5.1 Six-Sigma methodology

Six Sigmas methods include many of the statistical tools that were employed in

other quality movements, Six-Sigma is employed in a systematic project-oriented

fashion through define, measure, analyze, improve, and control (DMAIC) cycle. The

DMAIC cycle is a more detailed version of the Deming PDCA cycles, which

consists of four steps Plan, Do, Check, and Act within continuous improvement.

Continuous improvement, also called Kaizen, seeks continual improvement of

machinery, materials, labor utilization, and production methods through application

of suggestions and ideas of company teams. Like Six Sigma, it also emphasizes the

scientific method, particularly hypothesis testing about the relationship between

process inputs (Xs) and outputs (Ys) using design of experiments (DOE) methods.

The availability of modern statistical software has reduced the drudgery of analyzing

and displaying data and is now part of the Six-Sigma tool kit. The overarching focus

of the methodology, however is, understanding and achieving what the customer

wants, since that is seen as the key to profitability of a production process. In fact, to

get across this point, some use the DMAIC as an acronym for Dumb Managers

Always Ignore Customers.

The standard approach to Six-Sigma projects is the DMAIC methodology developed

by General Electric (G.E). The DMAIC methodology is central to Six Sigma process

improvement projects. The following phases provide a problem-solving process in

which specific tools are employed to turn a practical problem into a statisticalproblem, generate a statistical solution and then convert that back into a practical

solution (Henderson, Evans and et al, 2000).

DPMO = Number of defects

Number of opportunities for error per unit x Number of unit

X 1,000,000


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2.5.1.1 Define (D)

The purpose of the Define phase is to clearly identify the problem, the requirements

of the project and the objectives of the project. The objectives of the project should

focus on critical issues, which are aligned with the companys business strategy and

the customers requirements. The Define phase includes:

Define customer requirements as they relate to this project. Explicit

customer requirements are called Critical-to-Quality (CTQ)

characteristics;

Develop defect definitions as precisely as possible;

Perform a baseline study (a general measure of the level of performance

before the improvement project commences);

Create a team charter and Champion;

Estimate the financial impact of the problem; and

Obtain senior management approval of the project

Some of the key questions addressed in this stage are:

What matters to the customers?

What Defect are we trying to reduce?

By how much and by when?

What is the current Cost of defects?

Who will be in the project team?

Who will support us to implement this project?

The most applicable tools in this phase are the following:

Project Charter - this document is intended to clearly describe the

problem, defects definitions, team information and deliverables for a

proposed project and to obtain agreement from key stakeholders.

Trend Chart - to see (visually) the trend of defect occurrence over a

period of time.

Pareto Chart - to see (visually) how critical each input is in contributing

negatively or positively to total output or defects.


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Process Flow Chart - to understand how the current processes functions

and the flow of steps in current process

2.5.1.2 Measure (M)

The purpose of the Measure phase is to fully understand the current performance by

identifying how to best measure current performance and to start measuring it. The

measurements used should be useful and relevant to identifying and measuring the

source of variation. This phase includes:

Identifying the specific performance requirements of relevant Critical-to-

Quality

(CTQ) characteristics;

Map relevant processes with identified Inputs and Outputs so that at each

process step, the relevant Outputs and all the potential Inputs (X) that

might impact each Output are connected to each other;

Generate list of potential measurements

Analyze measurement system capability and establish process capability

baseline;

Identify where errors in measurements can occur;

Start measuring the inputs, processes and outputs and collecting the data;

Validate that the problem exists based on the measurements;

Refine the problem or objective (from the Analysis phase)


What is the Process? How does it function?

Which Outputs affect CTQs most?

Which Inputs affect Outputs (CTQs) most?

Is our ability to measure/detect sufficient?

How is our current process performing?

What is the best that the process was designed to do?


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The most applicable tools at this phase include the following:

Fishbone Diagram to demonstrate the relationships between inputs and

outputs

Process Mapping - to understand the current processes and enables the

team to define the hidden causes of waste.

Preliminary Failure Mode & Effect Analysis (FMEA) - using this in the

Measure phase helps to identify and implement obvious fixes in order to

reduce defects and save costs as soon as possible.

Gauge Repeatability & Reproducibility (GR&R) - used to analyze the

variation of components of measurement systems so minimize any

unreliability in the measurement systems.

2.5.1.3 Analyze (A)

In the Analyze phase, the measurements collected in the Measure phase are analyzed

so that hypotheses about the root causes of variations in the measurements can be

generated and the hypothesis subsequently validated. It is at this stage that practical

business problems are turned into statistical problems and analyzed as statistical

problems. This includes:

generate hypotheses about possible root causes of variation and potential

critical

Inputs (Xs);

identify the vital few root causes and critical inputs that have the most

significant impact; and

Validate these hypotheses by performing Multivariate analysis.


Which Inputs actually affect our Critical to qualitys most (based on

actual data)?

By how much?


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Do combinations of variables affect outputs?

If input is changed, does the output really change in the desired way?

How many observations are required to draw conclusions?

What is the level of confidence?

The Analyze phase offers specific statistical methods and tools to isolate the key

factors that are critical for a comprehensive understanding of the causes of

defects:

Tests for normality (Descriptive Statistics, Histograms) this is used to

determine if the collected data is normal or abnormal so as to be properly

analyzed by other tools.

Correlation/Regression Analysis - to identify the relationship between

process inputs and outputs or the correlation between two different sets of

variables.

Analysis of Variances (ANOVA) - this is an inferential statistical

technique designed to test for significance of the differences among two

or more sample means.

FMEA (Failure Mode and Effect Analysis) - applying this tool on current

processes enables identification of sufficient improvement actions to

prevent defects from occurring.

Hypothesis testing methods - these are series of tests in order to identify

sources of variability using historical or current data and to provide

objective solutions to questions, which are traditionally answered

subjectively.

Cause & Effect Matrix - to quantify how significant each input is for

causing variation of outputs.

2.5.1.4 Improve (I)

The Improve phase focuses on developing ideas to remove root causes of variation,

testing and standardizing those solutions. This involves:


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identify ways to remove causes of variation;

verify critical Inputs;

discover relationships between variables;

establish operating tolerances which are the upper and lower specificationlimits (the engineering or customer requirement) of a process for judging

acceptability of a particular characteristic, and if strictly followed will

result in defect-free products or services;

Optimize critical Inputs or reconfigure the relevant process.


Once we know for sure which inputs most affect our outputs, how do we

control them?

How many trials do we need to run to find and confirm the optimal

setting/procedure of these key inputs?

Who should the old process be improved and what is the new process?

How much have Defects per Millions Opportunities (DPMO) decreased?

The most applicable tools at this phase are:

Process Mapping - this tool helps to represent the new process subsequent

to the improvements.

Process Capability Analysis (Cpk) - in order to test the capability of

process after improvement actions have been implemented to ensure we

have obtained a real improvement in preventing defects.

DOE (Design of Experiment) - This is a planned set of tests to define the

optimum settings to obtain the desired output and validate improvements.

2.5.1.5 Control (C)

The Control phase aims to establish standard measures to maintain performance and

to correct problems as needed, including problems with the measurement system.

This includes:


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validate measurement systems;

verify process long-term capability;

Implement process control with control plan to ensure that the same

problems dont reoccur by continually monitoring the processes thatcreate the products or services.


Once defects have been reduced, how do we ensure that the improvement

is sustained?

What systems need to be in place to check that the improved procedures

stay implemented?

What do we set up to keep it going even when things change?

How can improvements be shared with other relevant people in the

company?

Most applicable tools at the Control phase include:

Control Plans this is a single document or set of documents that outlines

the actions, including schedules and responsibilities, which are needed to

control the key process inputs variables at the optimal settings.

Operating Flow Chart(s) with Control Points - this is a single chart or

series of charts that visually display the new operating processes.

Statistical Process Control (SPC) charts - these are charts that help to

track processes by plotting data over time between lower and upper

specification limits with a center line.

Check Sheets - this tool enables systematic recording and compilation of

data from historical sources, or observations as they happen, so that

patterns and trends can be clearly detected and shown (Hagemeyer and

Gershenson, 2005).


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2.6 Analytical tools for Six-Sigma and continuous improvement

The analytical tools of Six-Sigma have been used for many years in traditional

quality improvement programs. What makes their application to Six-Sigma unique is

the integration of these tools in a corporate wide management system. The tools

common to all quality efforts, including Six-Sigma, are flowcharts, run charts, Pareto

charts, histograms, check sheets, cause-and-effect diagrams, and control charts.

Examples of these, along with an opportunity flow diagram, are shown in Figure 2.1

to Figure 2.5 arranged according to DMAIC categories where they commonly

appear.

1. Flow charts. There are many types of flow charts. The one shown infigure 2.1 depicts the process steps as part of a SIPOC (supplier, input,

process, output and customer) analysis. SIPOC in essence is a formalized

input-output model, used in the define stage of a project.

Figure 2.1: An example of SIPOC analysis diagram for Define stage

(Hagemeyer,C. and Gershenson, J.K. (2005))


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2. Run charts shown in the Figure 2.2A. They depict trends in data over

time, and thereby help to understand the magnitude of a problem at the

define stage. Typically, they plot the median of a process.

3. Pareto charts shown in the Figure 2.2C. These charts help to break down a

problem into the relative contributions of its components. They are based

on the common empirical finding that a large percentage of problems are

due to a small percentage of causes. In the example, 80 percent of

customer complaints are due to late deliveries, which are 20 percent of the

causes listed.

4. Check sheets shown in Figure 2.2B. These are basic forms that helpstandardize data collection. They are used to create histograms such as

shown on the Pareto chart.

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