PRODUCT DESIGN IMPROVEMENT THROUGH INTEGRATION OF THEORY OF
INVENTIVE PROBLEM SOLVING (TRIZ) AND DESIGN FOR MANUFACTURE AND
ASSEMBLY (DFMA)
MUNIRA BT MOHAMED NAZARI
A project report submitted in partial fulfillment of the
requirements for the award of the degree of
Master of Mechanical Engineering (Advanced Manufacturing Technology)
Faculty of Mechanical Engineering
Universiti Teknologi Malaysia
APRIL 2010
iii
For my dad, mum, bro and sis,
Thank you for your love and support as well as funding me some valuable money.
Alhamdulillah, I managed to complete this project in time and without any
hindrances.
For all my beloved friends especially Mardianaliza, Norhazilina, Kak Aznee, Kak
Siti and Suliana,
Your help and kindness are so precious and irreplaceable with any valuable thing.
For my Master Project supervisor, Dr. Ariffin Abdul Razak,
Your commitment and advices are really helpful in completing this Master Project.
iv
ACKNOWLEDGEMENTS
All praises to the Al-Mighty Allah S.W.T, The Merciful and Beneficent for
the strength and blessing throughout the entire time until completion of this Master
Project report. Peace be upon our prophet Muhammad S.A.W, whose has given light
to mankind.
Firstly, I wish to express my sincere appreciation and gratitude to my Master
Project supervisor, Dr. Ariffin Abdul Razak for his guidance, counsels and for putting
much effort through his useful advice in this Master Project.
Secondly, I wish to give a special thank to Mr. Idris and Mr. Arman Syah for
their kindness in sharing the valuable information in starting this project.
I am also would like to thank to all my colleagues who are always giving me
support and help when I am lost. May ALLAH repay their sincere kindness.
Lastly, for each and everyone who involved either directly or indirectly in this
Master Project, their contribution is highly appreciated. The kindness corporation and
support from all of the above mentioned people would always be remembered.
Thank you.
v
ABSTRACT
Theory of Inventive Problem Solving (TRIZ) is one of the Value Engineering (VE)
systematic tools to improve the value of products by examination of function, by
which designer can systematically solve problems and enhance decision-making.
Design for Manufacture and Assembly (DFMA) is an approach to improve product
performance and to simplify product. This project report describes work to integrate
DFMA and TRIZ to improve and value added the current design of consumer
product. The used of TRIZ concept will eliminate the contradiction problem that
occurred during the process of improvement of the product by applying the principles
proposed by TRIZ. TRIZ had simplified 39 standard technical characteristics that
cause conflict. These are called the 39 Engineering Parameters. The conflict then can
be solved by referring to the 40 Inventive Principles. Results from case studies
showed that the integrating of DFMA and TRIZ can improve the product design
efficiency value, minimize assembly complexity, reduce the overall assembly time
and cost, and reduce the number of part in product improvement compared by just
using single tool.
vi
ABSTRAK
Teori Mencipta Penyelesaian Masalah (TRIZ) adalah salah satu peralatan sistematik
dalam Kejuruteaan Nilai (VE) untuk meningkatkan nilai sesuatu produk dengan
menganalisakan fungsinya, di mana pereka dapat menyelesaikan masalah secara
sistematik dan keputusan yang dibuat dapat ditingkatkan. Sementara itu, Rekabentuk
untuk Pembuatan dan Pemasangan (DFMA) adalah kaedah untuk meningkatkan
keupayaan produk dan memudahkan rekabentuk produk. Dalam laporan ini, kerja
untuk meningkatkan keupayaan produk dan penambahan nilai untuk rekabentuk
produk pengguna terkini dihuraikan dengan menggunakan kaedah pergabungan di
antara (DFMA) dan (TRIZ). Penggunaan konsep (TRIZ) akan menghapuskan
percanggahan masalah yang dihadapi semasa proses meningkatkan nilai produk
dengan mengaplikasikan prinsip yang dicadangkan oleh (TRIZ). (TRIZ) telah
menyimpulkan 39 sifat teknikal yang boleh menyebabkan konflik. Ia dipanggil 39
Parameter Kejuruteraan. Walaubagaimanapun, konflik tersebut dapat diselesaikan
dengan merujuk kepada 40 Prinsip Mencipta. Keputusan daripada kajian
menunjukkan pergabungan di antara (DFMA) dan (TRIZ) akan meningkatkan nilai
kecekapan
rekabentuk
produk,
meminimakan
kekompleksan
pemasangan,
mengurangkan masa dan kos pemasangan, dan mengurangkan bilangan jumlah
bahagian dalam pembangunan produk berbanding dengan hanya mengunakan satu
peralatan sahaja.
vii
TABLE OF CONTENTS
CHAPTER
1
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xiii
LIST OF FIGURES
xiv
LIST OF ABBREVIATIONS
xvi
LIST OF SYMBOLS
xvii
LIST OF APPENDICES
xviii
INTRODUCTION
1
1.1 Introduction to the problem
1
1.2 Objectives
2
1.3 Scope
2
1.4 Methodology of study
3
viii
2
1.5 Significant of study
5
1.6 Report structure
5
1.7 Summary
6
LITERATURE REVIEW
7
2.1
Introduction
7
2.2
Value Engineering
8
2.2.1
What is Value Engineering?
8
2.2.2
The Job Plan
9
2.2.3
How it Works?
11
2.3
Theory of Inventive Problem Solving (TRIZ)
12
2.3.1
History of TRIZ
12
2.3.2
What is TRIZ?
12
2.3.3
TRIZ Fundamental
13
2.3.3.1 Ideality
13
2.3.3.2 Functionality
14
2.3.3.3 Resource
15
2.3.3.4 Contradictions
17
2.3.3.5 Evolution
22
Additional TRIZ Tools
23
2.3.4
2.3.4.1 ARIZ (Algorithm for Inventive
Problem Solving)
24
2.3.4.2 Su-Field Analysis
24
2.3.4.3 Anticipatory Failure Determination
(AFD)
2.3.4.4 Directed Product Evolution (DPE)
2.3.5
25
Integration TRIZ with Others Problem
Solving Tools
2.4
24
27
Design for Manufacture and Assembly (DFMA)
29
2.4.1
What is DFMA?
29
2.4.2
The DFMA Approach
30
ix
2.5
3
Summary
TRIZ CONCEPT
33
3.1
Introduction
33
3.2
General TRIZ Process Procedures
34
3.2.1
Problem Definition
34
3.2.2
Problem Classification and Tool Selection
36
3.2.3
Solution Generation
37
3.2.4
Concept Evaluation
38
3.2.5
TRIZ Tool Selection
38
3.3
Technical Contradiction Elimination – Inventive
Principle Method
38
3.3.1
Identify the Problem
39
3.3.2
Formulate the Problem
40
3.3.3
Previously Well-Solved Problem
41
3.3.4
Look for Analogous Solutions & Adapt
To the Solution
3.4
4
32
Summary
41
45
PRODUCT CASE STUDY
46
4.1
Introduction
46
4.2
Product as Case Study
47
4.2.1
Product Selection
47
4.2.2
Product Tree Structure
48
4.2.3
Part ID Number
50
4.2.4
Assembly Sequence
51
4.3
Part Critique
51
4.4
Summary
56
x
5
6
DESIGN FOR ASSEMBLY (DFA) ANALYSIS
FOR ORIGINAL DESIGN
57
5.1
Introduction
57
5.2
Classification of Product parts
58
5.3
Theoretical Minimum Parts Assessment
59
5.4
DFA Worksheet
60
5.5
Result
62
5.6
Summary
63
PROPOSED IMPROVEMENT OF NEW
DESIGN USING DFMA METHODOLOGY
AND TRIZ CONCEPT
64
6.1
Introduction
64
6.2
Improvement by Using DFMA Methodology
65
6.2.1
Improvement 1: Connector
65
6.2.2
Improvement 2: Wiper Holder
66
6.2.3
Improvement 3: Male Adjuster
67
6.2.4
Improvement 4: Female Adjuster
68
6.2.5
Improvement 5: Stopper
69
6.2.6
Improvement 6: Rod A
70
6.2.7
Improvement 7: Handle
71
6.2.8
Improvement 8: Joint
71
6.2.9
Improvement 9: Snap Fit Shaft
72
6.3
6.2.10 Improvement 10: Pusher
73
Improvement by Using TRIZ Concept
74
6.3.1
Improvement1: Pusher
74
6.3.2
Improvement 2: Male and Female Adjuster 75
6.3.3
Improvement 3: Joint
6.3.4
Improvement 4: Wiper Holder, Connector,
76
xi
Arms and Pins
6.4
7
79
DFMA AND TRIZ ANALYSIS FOR NEW
DESIGN
80
7.1
Introduction
80
7.2
DFMA Analysis for New Design
81
7.2.1
Classification of Product Parts
82
7.2.2
Theoretical Minimum Parts Assessment
83
7.2.3
DFA Worksheet
83
7.2.4
Result
85
7.2.5
DFM Analysis
86
7.3
7.4
8
Summary
77
TRIZ Analysis for New Design
87
7.3.1
Classification of Product Part
88
7.3.2
DFA Worksheet
89
7.3.3
Result
90
7.3.4
DFM Analysis
91
Summary
91
DISCUSSION
92
8.1
Introduction
92
8.2
Comparison of Product Case Study Result
93
8.2.1
Comparisons of DFMA Analysis Result
93
8.2.2
Comparisons of TRIZ Analysis Result
95
8.2.3
Comparisons between DFMA and TRIZ
Improvement Result
8.3
Summary
98
99
xii
9
CONCLUSION
100
9.1
Introduction
100
9.2
Recommendations for Future Work
101
9.3
Concluding Remark
103
REFERENCES
105
APPENDICES
108
xiii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
VE evaluation process.
11
2.2
Table of 39 parameters of contradiction
18
2.3
Table of 40 inventive principles
19
2.4
Pattern of evolution of technological systems
25
3.1
Table characteristic of beverage can through Innovative
Situation Questionnaire
40
4.1
The Sponge Mop part ID number
50
4.2
Part critique of each part for Sponge Mop
52
5.1
Classification of Part for Original Design
58
5.2
DFA worksheet analysis for original design
60
7.1
Classification of Part for New Design by DFMA
Methodology
7.2
82
DFA worksheet analysis for new design by DFMA
Methodology
84
7.3
Classification of Part for New Design by TRIZ Concept
88
7.4
DFA worksheet analysis for new design by TRIZ
89
8.1
Effect of the improvement
93
8.2
Result of time saving due to the factor of design change
94
8.3
Effect of the improvement result
95
8.4
Effect of the integration improvement
98
xiv
LIST OF FIGURES
FIGURE NO
TITLE
PAGE
1.1
Flow chart of the project activities for MP 1 and MP 2.
4
2.1
Three steps to pre-analyze the conflict.
21
2.2
Curves of technical system evolution.
23
2.3
Integration of design problem-solving tools.
28
3.1
Four steps TRIZ process procedure.
34
3.2
Technical Contradiction Elimination – Inventive
Principle step-by-step.
39
3.3
Result for the problem.
42
3.4
Cross section of corrugated can wall.
43
3.5
Spheroidality Strengthens Can's Load Bearing Capacity.
Perpendicular angle has been replaced with a curve.
44
4.1
Sponge Mop.
48
4.2
Sponge Mop product tree structure.
49
6.1
Design improvement of Connector.
66
6.2
Design improvement of Wiper Holder.
67
6.3
Design improvement of Male Adjuster.
68
6.4
Design improvement of Female Adjuster.
69
6.5
Design improvement of Stopper.
70
6.6
Design improvement of Rod A.
70
6.7
Design improvement of Handle.
71
6.8
Design improvement of Joint.
72
6.9
New part design of Snap Fit Shaft.
73
xv
6.10
Improvement of Pusher quantity from two into one.
6.11
New design of Pusher by combining two pushers into one. 75
6.12
(a) New design of male adjuster with lock leaf, and
(b) New design of female adjuster with lock slot.
6.13
78
Exploded drawing of new design of Sponge Mop via
DFMA methodology
7.2
78
New design of wiper holder that designing to fit with the
new connector design.
7.1
76
New design of connector based on idea from element in
Principle 1.
6.14
73
81
Exploded view of new design of Sponge Mop via
TRIZ concept
87
xvi
LIST OF ABBREVIATIONS
TRIZ -
Theory of Inventive Problem Solving
VE
Value Engineering
-
DFMA -
Design for Manufacture and Assembly
MP 1 -
Master Project 1
MP 2 -
Master Project 2
DFA
Design for Assembly
-
DFM -
Design for Manufacture
VA
Value Analysis
-
ARIZ -
Algorithm for Inventive Problem Solving
QFD
Quality Function Deployment
-
FMEA -
Failure Mode Effect and Analysis
6σ
-
Six Sigma
ID
-
Identification
Q&A -
Question and Answer
TM
-
Assembly time
CM
-
Assembly cost
NM
-
Theoretical minimum number of part
DE
-
Design efficiency
xvii
LIST OF SYMBOLS
α
-
Alpha
β
-
Beta
n
-
Labor cost per second
xviii
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
1A
Gantt chart 1: Project activities for Master Project Part 1
109
1B
Gantt chart 2: Project activities for Master Project Part 2
110
2A
Contradiction Table of 39 Parameters
111
2B
The 40 Inventive Principles
117
2C
DFA Worksheet
130
2D
Table of Manual Handling Estimated Times
131
2E
Table of Manual Insertion Estimated Times
132
2F
Table of Compatibility between Processes and Materials
133
2G
Table of Shape Generation Capabilities of Processes
134
7A
Part Attributes of Each Part for New Design of
Sponge Mop
7B
Table of Primary Process and Material Selection for
New Design
7C
136
Part Attributes of Each Part for New Design of Sponge
Mop by TRIZ Concept
7D
135
138
Table of Primary Process and Material Selection for
New Design by TRIZ Concept
139
CHAPTER 1
INTRODUCTION
1.1
Introduction to the Current Product Development Problem
Now a day, product design simplification is important due to the rapid
changing of customer demands, more competition and so on. Yet, manufacture is
being forced to produce product that meet the customer requirement with high
expectation such as product functionality but in lower cost. So, designer needs to
design product with maximize value in order to fulfill that requirement. In recent
decades the search for significant cost-saving effects that characterize major process
innovations has driven manufacturers towards simplifying their products. In fact,
when compared to process improvements in the production of complex assembled
products, product innovations have a more profound impact on productivity, costs
and quality [1].
Basically, there are two sort of problems for any given product design or
process which are those where the solution is generally known and those where it is
not. If the solution is generally known, it can be found in books, journals, or technical
paper. Problems where the solutions are not generally known are called inventive
problems and often offer contradiction requirements. Mostly, many people will
2
choose a compromised solution, where not all of the requirements are met and those
that are met, are not optimized in order to resolve contradictory requirements or
conflict [2]. In this case, there are several ways to solve the problem. The use of
integrated several VE tools will help to resolve conflict and generate new solutions
from outside the experience.
1.2
Objective
To integrate Theory of Inventive Problem Solving (TRIZ) tool, and Design
for Manufacture and Assembly (DFMA) methodology in order to improve and value
added the current design of consumer product
1.3
Scope
The study will focus on the:
i)
Application of DFMA methodology to identify detailed design problems and
generate remedial design solutions.
ii)
Application of TRIZ method to improve the value added product
development.
iii)
Consumer product as case study – Sponge Mop
3
1.4
Methodology of Study
This thesis is conducted accordingly in two parts which is Master Project 1
(MP 1) in semester 1 and Master Project 2 (MP 2) in semester 2 as shown in Figure
1.1. The flow chart showed clearly the processes of the thesis activities in order to
meet the time constrain. After the project had determined, the literature review on
VE, DFMA and TRIZ methodology are studied in the early stage. The studies are
done by reviewing the related books, journals and articles. For a while, the consumer
product for the project analysis purpose is also been selected. The selected product
then is been evaluated by using DFMA methodology and from the results some
improvements are proposed.
However, the proposed improvement activities will be continuing also in the
MP 2. It is continuously process as in the stage of evaluation the new design with
using integrated VE tools, it may have some unsuitability idea. So, the others
proposed improvement need to do. Lastly, the discussion and conclusion will be done
after the accurate analysis result on the new design is evaluated where, the new
design of integration tools is compared to the new design of DFMA methodology in
terms of percentages of part count reduction and design efficiency increment.
4
Literature Review on DFMA and TRIZ Methodology
Discussion of the Both Designs
Figure 1.1: Flow chart of the project activities for MP 1 and MP 2.
5
1.5
Significant of Study
The significant of this thesis is to prove the use of integration of VE tools will
give a better result of product design in term of simplification, product cycle life,
efficiency, quality, function and also product value. In this thesis, product design
improvement is done by integration of TRIZ and DFMA methodology. Hopefully
with the result of this study, it can give an overview to others about the advantages of
using integration problem solving tool in product development and then will attract
more organization to use this method for their product development purpose.
The result of integration problem solving tools should achieve improvement
better than single tool with the main improvement is to reduce assembly and
manufacture process time and cost. However, in case the improvement in term of cost
and time does not show much improvement, the others factor such as product
simplification, function and life cycle should be considered.
1.6
Report Structure
This thesis consists of nine chapters. Chapter 1 presents the introduction of
the thesis, Product Design Improvement through TRIZ and DFMA methodology
where the topic include are objective, scopes, methodology of study and significant
of study of the project. The literature reviews in Chapter 2 reports on relevant
previous findings that are related to the research and also the review of the related
discusses topics. The detail information on the research methods and tools that will
be used in the case study is explained in Chapter 3. For the Chapter 4, the data
information of the product case study will be explained in details. The next chapter
consists of the original data analysis of the product case study. In this Chapter 5, the
DFMA Methodology is applied. The proposed improvement of the original data case
6
study then been discussed in Chapter 6. This chapter covers both of the selected
design problem solving tools. The analysis of the new improvement of the product
case study then discussed in Chapter 7. The discussion of the case study result is in
Chapter 8, while the conclusion of the case study is concluded in Chapter 9.
The time management of all activities for the MP, Product Design
Improvement through VE and DfMA methodology project is shown in Gantt chart
MP 1 (Appendix 1A) and Gantt chart MP 2 (Appendix 1B).
1.7
Summary
Through this thesis, the objective of the project is hopefully achieved as
expected which is contained the important result such as success to improve
design of the product case study by applying the selected methods and also develop a
product that have maximize value, convenience, suitable and easy to use by the
consumer. On the other hand, this chapter is providing information about the aim for
the rest of the chapter.
CHAPTER 2
LITERATURE REVIEW ON VALUE ENGINEERING (VE)
DESIGN FOR MANUFACTURE AND ASSEMBLY (DfMA)
AND TRIZ METHODOLOGIES
2.1
Introduction
This chapter discusses on the important of Value Engineering (VE) tools in
product design, basic principle of the design problem solving tools which are TRIZ
and DfMA methodologies, and also example the application of the both tool in
simplify and improving product design. All
discussing
about
the
objectives
of
of
this
this
related
thesis project,
topic actually
Product Design
Improvement through VE and DfMA methodology.
The integration of TRIZ and DfMA is studied and applied in order to show
how product can be improved into a maximize value.
8
2.2
Value Engineering
The beginning decade of twenty first century witnessed several changes like
world wide in technology management, restricting and down sizing global trade and
competition,
international
quality
standards,
information
exchange,
lean
manufacturing and virtual enterprises. In this age of globalization, the survival of any
industry mainly depends on its cost of production and quality of its products. With
the rapid growth of competition and shrinking product life cycle, Value Engineering
(VE) has become an essential tool for getting a competitive edge.
2.2.1
What is Value Engineering?
Value Engineering (VE) is a systematic tool to improve the “value” of goods
or products and services by using an examination of function. Value is maximized by
optimizing the equation:
Value = Function / Cost
Value can therefore be increased by either improving the function or reducing the
cost. It is a primary tenet of VE that basic functions be preserved and not be reduced
as a consequence of pursuing value improvement [3].
VE technique emerged during the years of World War II (1938-45) and was
developed by Lawrence D Miles, a purchase engineer in General Electric Co. (GEC).
In view of scarcity of vital defense material, he came up with the basic theme: “If I
cannot get the product, I have got to get the function.” Thus, “function” grew in
vitality and later matured into the development of the VE techniques. In 1947, this
9
approach was develop, refined and utilized in GEC and first known by the name
Value Analysis (VA).
VE is sometimes taught within the project management or industrial
engineering body of knowledge as a technique in which the value of a system’s
outputs is optimized by crafting a mix of performance (function) and costs. In most
cases this practice identifies and removes unnecessary expenditures, thereby
increasing the value for the manufacturer and/or their customers.
VE uses rational logic (a unique "how" - "why" questioning technique) and
the analysis of function to identify relationships that increase value. It is considered a
quantitative method similar to the scientific method, which focuses on hypothesisconclusion approaches to test relationships, and operations research, which uses
model building to identify predictive relationships.
2.2.2
The Job Plan
Value engineering is often done by systematically following a multi-stage job
plan. Lawrence Miles' original system was a six-step procedure which he called the
"value analysis job plan." The plan consists of below six sequential steps:
1. Information Phase
2. Function Analysis Phase
3. Creative Phase
4. Evaluation Phase
5. Development Phase, and
6. Presentation & Implementation Phase
10
However, others have varied the job plan to fit their constraints. Depending on
the application, there may be four, five, six, or more stages. One modern version has
the following eight steps:
1. Preparation
2. Information
3. Analysis
4. Creation
5. Evaluation
6. Development
7. Presentation
8. Follow-up
Four basic steps in the job plan are:
•
Information gathering - This asks what the requirements are for the object.
Function analysis, an important technique in value engineering, is usually
done in this initial stage. It tries to determine what functions or performance
characteristics are important. It asks questions like; What does the object do?
What must it do? What should it do? What could it do? What must it not do?
•
Alternative generation (creation) - In this stage value engineers ask; What are
the various alternative ways of meeting requirements? What else will perform
the desired function?
•
Evaluation - In this stage all the alternatives are assessed by evaluating how
well they meet the required functions and how great will the cost savings be.
•
Presentation - In the final stage, the best alternative will be chosen and
presented to the client for final decision.
11
2.2.3
How it Works?
VE follows a structured thought process to evaluate options as follows.
Table 2.1: VE evaluation process.
STEP
ACTION
Gather information
1. What is being done now?
Measure
Who is doing it?
What could it do?
What must it not do?
2. How will the alternatives be measured?
Analyze
What are the alternate ways of meeting
requirements?
What else can perform the desired function?
3. What must be done?
Generate
What does it cost?
4. What else will do the job?
Evaluate
5. Which Ideas are the best?
6. Develop and expand ideas
What are the impacts?
What is the cost?
What is the performance?
7. Present ideas
Sell alternatives
12
2.3
Theory of Inventive Problem Solving (TRIZ)
Theory of Inventive Problem Solving was called TRIZ because regarding to
the Romanized acronym for Russian words ‘Teoriya Resheniya Izobretatelskikh
Zadatch’ which means ‘The theory of inventor’s problem solving’. Basically, TRIZ
is a methodology, tool set, and knowledge base for generating innovative ideas and
solutions for problem solving. TRIZ provides tools and methods for use in problem
formulation, system analysis, failure analysis, and patterns of system evolution. TRIZ
concept are difference to the techniques such as brainstorming (which is based on
random idea generation), aims to create an algorithmic approach to the invention of
new systems, and refinement of old systems [4].
2.3.1
History of TRIZ
It was developed by a Soviet engineer and researcher Genrich Altshuller and
his colleague starting in 1946. At the age of 20, Altshuller developed his first mature
invention – a method for escaping from an immobilized submarine without diving
gear in year 1946. He then worked for the “Inventions Inspection” department of the
Caspian Sea flotilla of the Soviet Navy in Baku in the late of 1940s. Atshuller’s job
was to inspect invention proposals, help document them, and help others to invent.
2.3.2
What is TRIZ?
Darrel Mann claims TRIZ is a combination of methods, tools, a way of
thinking in the article entitled “Hands on Systematic Innovation” [5]. The goal of
TRIZ is to achieve absolute excellence in design and innovation. In order to achieve
absolute excellence, TRIZ has five key philosophical elements which are ideality,
functionality, resource, contradictions and evaluation. Based on these philosophical
elements, TRIZ developed a system of methods. This system of methods is a
13
complete problem definition and solving process. It is a four step process that starting
with the problem definition, problem classification and tool selection, solution
generation and end the process by concept evaluation.
2.3.3
TRIZ Philosophical Elements
As discussed before, TRIZ has five key philosophical elements can be follow
in order to achieve the absolute excellent design and innovation. Below are the details
about the five key philosophical elements in TRIZ.
2.3.3.1 Ideality
Ideality is defined in similar terms to ‘value’. It is typically defined as benefits
divided by cost and harm.
Ideality = Where,
∑ Benefits = sum of the values of systems useful functions. (Here the
supporting functions are not considered to be
useful functions, because they will not bring
benefits to customer directly. We considering
supporting functions are part of the costs to make
the system work).
∑ Costs
= sum of the expenses for systems performance.
∑ Harm
= sum of “harms” created by harmful functions.
14
Regarding to the ideality equation, a higher ration indicates a higher ideality.
Through this, when a new system achieve a higher ration than the old system, we can
considered it as a real improvement. In TRIZ, there is a “law of increasing ideality,”
which states that the evolution of all technical system proceeds in the direction of
increasing degree of ideality. The ideality of the system will increase in the following
factors:
1. Increasing benefits.
2. Reducing costs
3. Reducing harms
4. Benefits increasing faster than costs and harms.
In terms of TRIZ, any technical system or product is not a goal in itself. The
real value of the product/system is in its useful functions. Therefore, the better system
is the one that consumes fewer resources in both initial construction and maintenance.
When the ratio becomes infinite, we call that the “Ideal Final Result” (IFR). Thus, the
IFR system requires no material, consumes no energy and space, needs no
maintenance, and will not break.
2.3.3.2 Functionality
Function and functionality are very important in the TRIZ context. Functions
(benefits) are the things that customers want. TRIZ encourage users to focus on the
functional relationship between the different components within and around a system.
Typically this is done through an evolved version of the function analysis/value
engineering methods originally developed by Miles. The innovation introduced by
TRIZ has been the modeling of the negative as well as positive functional
relationships in a system. This enables users to define both the problems present in a
system and the most appropriate tools to help solve them. By forcing users to
examine a system on a component by component basis, the tool enables systematic
15
management of complexity. Latterly, the method has further advanced to better take
into account manufacture and assembly process systems. Another important aspect of
TRIZ is that it uses function as the principle means of classifying knowledge.
Knowledge classification by function enables users to access, for example, all known
ways of ‘moving liquids’ or ‘joining surfaces’, etc very rapidly.
2.3.3.3 Resource
Maximum effective use of resources is very important in TRIZ. Besides that,
we need to think of resources and make use of resources in creative ways. For any
product or process, its primary mission is to deliver functions. Because substances
and fields are the basic building blocks of functions, they are important resources
from TRIZ point of view. However, substances and fields alone are not sufficient to
build and deliver functions, the important resources, space and time, are also needed.
In the TRIZ point of view, information and knowledge base are also important
resources. Resources can be segmented into the following categories.
1. Substance resources:
i.
Raw material and products
ii.
Waste
iii.
By-product
iv.
System elements
v.
Substances from surrounding environments
vi.
Inexpensive substance
vii.
Harmful substance from the system
viii.
Altered substance from system
2. Field resources:
i.
Energy in the system
ii.
Energy from the environment
16
iii.
Energy/field that can be built upon existing energy platforms
iv.
Energy/field that can be derived from system waste
3. Space resources:
i.
Empty space
ii.
Space at interfaces of different systems
iii.
Space created by vertical arrangement
iv.
Space created by nesting arrangement
v.
Space created by rearrangement of existing system elements
4. Time resources:
i.
Prework period
ii.
Time slot created by efficient scheduling
iii.
Time slot created by parallel operation
iv.
Postwork period
5. Information/knowledge resources:
i.
Knowledge on all available substances (material properties,
transformation, etc.)
ii.
Knowledge on all available fields (field properties, utilizations,
etc.)
iii.
Past knowledge
iv.
Other peoples knowledge
v.
Knowledge on operation
6. Functional resources:
i.
Unutilized or underutilized existing system main functions
ii.
Unutilized or underutilized existing system secondary functions
iii.
Unutilized or underutilized existing system harmful functions
17
2.3.3.4 Contradictions
This philosophy can be expressed as either a technical contradiction or
physical contradiction.
i.
Technical contradiction
A technical contradiction is a situation in which effects to improve some
technical attributes of a system will lead to deterioration of other technical attributes.
For example, as a container becomes stronger, it becomes heavier, and faster
automobile acceleration reduces fuel efficiency. A technical contradiction is present
when
The useful action simultaneously causes a harmful action.
Introducing (intensification) of the useful action, or elimination or
reduction of the harmful action causes deterioration or unacceptable
complication of the system or one of its parts.
A problem associated with a technical contradiction can be resolved by either
finding a trade-off between the contradictory demands or overcoming the
contradiction. Trade-off or compromise solutions do not eliminate the technical
contradiction but rather soften them, thus retaining the harmful (undesired) action or
shortcoming in the system. Analysis of thousands of inventions by Altshuller resulted
in formulation of typical technical contradictions such as productivity versus
accuracy, reliability versus complexity, and shape versus speed. It was discovered
that despite the immense diversity of technological systems and ever greater diversity
of inventive problems, there are only about 1250 typical system contradictions. These
contradictions can be expressed as a table of contradiction of 39 parameters. (Table
2.2 and Appendix 2A)
18
Table 2.2: Table of 39 parameters of contradiction.
1
2
3
4
5
6
7
8
Weight of movable
object
Weight of fixed object
Length of movable
object
Length of fixed object
Area of movable object
Area of fixed object
Volume of movable
object
Volume of fixed object
9 Speed
10 Force
11 Stress, pressure
12 Shape
Objects composition
13 stability
14 Strength
Duration of moving
15 objects operation
Duration of fixed objects
16 operation
17 Temperature
18 Illumination
Energy expense of
19 movable object
Energy expense of fixed
20 object
21
Power
22 Waste of energy
23
Loss of substance
24 Loss of information
25 Waste of time
26 Quantity of substance
Reliability
27
28 Measurement accuracy
29 Manufacturing precision
30 Harmful action at object
31 Harmful effect caused by the object
32 Ease of manufacture
33
Ease of operation
34 Ease of repair
35
Adaption
Device complexity
36
37 Measurement or test complexity
38 Degree of automation
39
Productivity
From the TRIZ standpoint, overcoming a technical contradiction is very
important because both attributes in the contradiction can be improved drastically and
system performance will be raised to a whole new level. TRIZ developed many tools
for elimination of technical contradiction. One of it is technical contradiction
elimination – inventive principles. In this tool, its expressed the contradictions into a
matrix of 39 x 39 “engineering parameters’. To resolve these contradictions,
19
Altshuller compiled 40 principles (Table 2.3). Each of these principles contains a few
sub-principles, totaling up to 89 sub-principles (Appendix 2B).
Table 2.3: Table of 40 inventive principles.
1
2
3
4
5
6
Segmentation
Extraction
Local Quality
Asymmetry
Combining
Universality
21
22
23
24
25
26
7
Nesting
27
8
Counterweight
28
9
10
11
12
13
14
Prior counter-action
Prior action
Cushion in advance
Equipotentiality
Inversion
Spheroidality
29
30
31
32
33
34
15
Dynamicity
35
16
17
18
19
20
Partial or overdone action
Moving to a new dimension
Mechanical vibration
Periodic action
Continuity of a useful action
36
37
38
39
40
Rushing through
Convert harm into benefit
Feedback
Mediator
Self service
Copying
Inexpensive, short-lived object for
expensive, durable one
Replacement of a mechanical
system
Pneumatic or hydraulic
construction
Flexible membrances or thin film
Use of porous material
Changing the color
Homogeneity
Rejecting and regenerating parts
Transformation of the physical
and chemical state of an object
Phase transformation
Thermal expansion
Use strong oxidizers
Inert environment
Composite material
It should be noted that the 40 principles are formulated in a general way. If,
for example, the contradiction table recommends principle 30, “flexible shell and thin
films”, the solution of the problem relates somehow to change the degree of
flexibility or adaptability of a technical system being modified. The contradiction
table and the 40 principles do not offer a direct solution to the problem. It only
suggests the most promising directions for searching for a solution. To solve the
20
problem, one has to interpret these suggestions and find a way to apply them to a
particular situation.
When using the contradiction table and 40 principles, following this simple
procedure will be helpful.
i. Decide which attribute be improved, and use one of the 39 parameters in the
contradiction table to standardize or model this attribute.
ii. Answer the following questions:
a. How can this attribute be improved using the conventional means?
b. Which attribute would be deteriorated if conventional means were used?
iii. Select an attribute in the contradiction table.
iv. Using the contradiction table, identify the principles in the intersection of the
row (attributed improved) and column (attribute deteriorated) for overcoming
the technical contradiction.
ii.
Physical contradiction
Usually, contradiction often encounter first as a technical contradiction.
However, after digging deeper into the problem, the fundamental cause of the
technical contradiction is often a physical contradiction. A physical contradiction is a
situation in which a subject or an object has to be in mutually exclusive physical
state. A physical contradiction has a typical pattern: “To perform function A1, the
element must have property B, but to perform function A2, it must have property –B,
or the opposite of P”. In this tool, physical contradiction resolution/separation
principles is using. The processes of the principle are as follow.
a) Analyze the physical contradiction
In order to identify the physical contradiction that causes the technical
contradiction, these three steps are recommended to follow in order to preanalyze the conflict:
21
Step 1
Step 2
Step 3
Capture the functions involved in the conflict and
established the functional model for the contradiction.
Identify the physical contradiction.
Identify the zones of conflict.
i. Locations properties of conflict.
ii. Times properties of conflict.
Figure 2.1: Three steps to pre-analyze the conflict.
b) Separate the physical contradiction
After the identification of the physical contradiction, TRIZ has the
following four approaches for resolving the contradiction. They are
separation in space, separation in time, separation between components,
and separation between components and set of components.
i. Separation in space.
Separation in space means one part of object has property P, while
another part has an opposite property –P. by this separation the
physical contradiction can be resolved. In order to accomplish the
separation, we need to study the zones of conflict requirements.
ii. Separation in time.
Separation in time means that at one time period an object has
property P, and at another time period it has an opposite property –P.
in order to accomplish this, we need to study the time property of the
conflict. If it is again a conflict of useful action versus harmful action,
we need to identify the periods of both of useful action and the
22
harmful action. We must then identify the time periods when the
useful function has to be performed and harmful function eliminated.
If we can separate these two periods completely, we may be able to
eliminate this contradiction.
iii. Separation between the components
Separation between the components means that one component has
property P, while another component is given an opposite property –
P. Sometimes we can limit the number of properties of the component
involved in the conflict to one, and we introduce another component
to have another property.
iv. Separation between components and the set of the components
This is an approach that has a set of components made; where every
single component must have one property but the whole set of
components will have another property.
2.3.3.5 Evolution
TRIZ found that the trends of evolution of many technical systems are very
similar and predictable. Many technical systems will go through five stages in their
evolution processes which are pregnancy, infancy, growth, maturity, and decline. If
we put time line in the horizontal axis, and plot;
a. Performance
b. Level of inventiveness
c. Number of inventions
d. Profitability
23
Maturity
Growth
Decline
Maturity
Growth
Decline
Infanc
y
Level of
Performanc
on the vertical axis, then we will get the four curves shows in Figure 2.2.
Infanc
y
Time
Infanc
y
Profit
Number of
Decline
Maturity
Growth
Time
Decline
Maturity
Growth
Infanc
y
Time
Time
Figure 2.2: Curves of technical system evolution (Kai Yang, 2003).
2.3.4
Additional TRIZ Tools
The TRIZ methodology can be adapted to different kinds of problem solving.
The method described above is relatively simple but forces the user to pre-formulate
the problem in terms of standard engineering parameters. It rarely leads to an
exhaustive set of solutions. More difficult problems are solved with the following
more precise tools.
24
2.3.4.1 ARIZ (Algorithm for Inventive Problem Solving)
A systematic procedure for identifying solutions without apparent contradictions.
Depending on the nature of the problem, anywhere from five to sixty steps may be
involved. From an unclear technical problem, the underlying technical problem can
be revealed. Can be used with levels two, three, and four problems. Basic steps
include
1. Formulate the problem.
2. Transform the problem into a model.
3. Analyze the model.
4. Resolve physical contradictions.
5. Formulate ideal solution.
2.3.4.2 Su-Field Analysis
A tool for expressing function statements in terms of one object acting on
another object. The objects are called substances and the action a field. Su-field
analysis is helpful in identifying functional failures. By looking at actions as fields,
undesirable or insufficient actions can be countered by applying opposing or an
intensified fields.
2.3.4.3 Anticipatory Failure Determination (AFD)
Prevention of unanticipated failures is important in new product development.
AFD, in effect, invents failure mechanisms and then examines the possibilities of
25
their actually occurring. Factors contributing to the failures can be eliminated with
this highly pro-active technique.
2.3.4.4 Directed Product Evolution (DPE)
Traditional technological forecasting tries to predict the "future characteristics
of machines, procedures, or techniques." It relies on surveys, simulations, and trends
to create a probabilistic model of future developments. It gives a forecast, but does
not invent the technology being forecasted.
Altshuller, by studying hundreds of thousands of patents, was able to
determine eight patterns of how technological systems develop over time. Based upon
the patterns of how people think rather than what people think, DPE is like a road
map into the future. Rather than predicting future technologies, one can
systematically invent future technologies using DPE. The eight patterns of Directed
Product Evolution are given in Table 2.4. Examples will also be shown.
Table 2.4: Pattern of evolution of technological systems.
Pattern
1.
Technology
follows a life
cycle of birth,
growth,
maturity,
decline.
Example
Stage 1. A system does not
yet exist, but important
conditions for its emergence
are being developed.
Stage 2. A new system
appears due to high-level
invention, but development is
slow.
Stage 3. Society recognizes
value of the new system.
Case Study: Airplane
26
Stage 4. Resources for
original system concept end. 1. Manual attempts to fly
fail.
Stage 5. Next generation of
system emerges to replace
2. Wright Brothers fly at
original system.
30mph in biplane.
Stage 6. Some limited use of 3. Military use in WWI.
original system may coexist Financial resources
with new system.
available. Speeds increase to
100mph.
4. Wood and rope frame
aerodynamics reach limit.
5. Metal frame monoplane
developed.
6. Several new types of
airplanes have been
developed but limited use of
biplanes still exists.
2.
Increasing
Ideality.
ENIAC computer in 1946 weighed several tons, took a
whole room, and did computational functions. In 1995,
Toshiba Portégé 610CT weighs 4.5 pounds and is capable
of text processing, mathematical calculations,
communications, graphics, video, sound.
3.
Uneven
development of
subsystems
resulting in
contradictions.
Subsystems have different life cycle curves. Primitive
subsystems hold back development of total system.
Common mistake is to focus on improving wrong
subsystem. Poor aerodynamics were limitations of early
planes but developers focused engine power instead of
improving aerodynamics.
4.
Increasing
dynamism and
controllability.
Early automobiles were controlled by engine speed. Then
manual gearbox, followed by automatic transmissions, and
continuously variable transmissions (CVT.)
5.
Increasing
complexity,
followed by
simplicity
through
integration.
Stereo music systems have evolved from adding separate
components such as speakers, AM/FM radio, cassette
player, CD player, etc. to integrated "boom box."
6.
Matching and
mismatching of
parts.
1. Early automobiles used leaf springs to absorb
vibration. These were an assembly of unrelated or
mismatched parts borrowed from horse carriages
27
and whatever else was available.
2. Later fine tuning allowed adjustments of the parts so
that they mated into a matched system - the shock
absorber.
3. Purposely mismatch parts to create additional
resources from the differences. An example of this
might be using a bimetal spring that changed spring
rates when a current is applied.
4. Automatic matching and mismatching as needed.
For example a computer controlled active
suspension system.
7.
Transition from
macrosystems
to microsystems
Development of cooking systems from wood burning stove
using energy
fields to achieve to gas ranges to electric ranges to microwave ovens.
better
performance or
control.
8.
Decreasing
human
involvement
with increasing
automation.
2.3.5
Development of clothes washing from washboard to
washing machine with ringer to automatic washing machine
to automatic washing machine with automatic bleach and
softener dispensers.
Integration TRIZ with Others Problem Solving Tools
From survey that done by Zhongsheng Hua, Jie Yang, Solomani Coulibaly
and Bin Zhang, TRIZ had been integrated with various method of problem solving
tool from years 1995-2005 such as shown in Figure 2.3. The survey showed that
TRIZ becomes a value added to the result of the problem that done by the stand alone
problem solving tool method. As an example, TRIZ is a useful tool that can solve the
problem of ‘how to do’ effectively in the innovative design process, while Quality
Function Deployment (QFD) is able to settle the problem of ‘what to do’ (Wang et
al., 2005). Another example, the application of Taguchi’s Robust Design makes it
28
possible to optimize the implementation details of the solutions generated by TRIZ
and makes the product design specifications insensitive to uncontrolled influences.
This integration was explored by references (Verduyn and Wu, 1995; Terninko,
1997; Jugulum and Sefik, 1998; Thimothy, 1998; Novick, 1999; Cavallucci and Lutz,
2000; Schulz et al., 2000; Luke, 2001; Park, 2003; Slocum et al., 2003; Zhao, 2003;
Phadke and Smith, 2004).
Besides that, the result of survey also shows that TRIZ largely applied with
others problem solving tool in the design phases in new product development process
where TRIZ solve the contradiction occurred in the early of the design and
improvement processes. It seems TRIZ also is needed in order to finalize the decision
in selecting concept of the product and also in developing the detail design of
product. In others word, application of TRIZ is important to define the conflicts, and
then based on the conflicts, to develop innovation solution.
VA
Global8D
6σ
TOC
Others
NM
Method
DFMA
QFD/FA
MindMaps
VA
AD
MBI
Brains
tormin
FME
A
Robus
t
NLP
KAI
Six
Hats
Figure 2.3: Integration of design problem-solving tools (Zhongsheng Hua, Jie
Yang, Solomani Coulibaly and Bin Zhang, 2006).
29
2.4
DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA)
There are several DFMA methods that commonly used which are BoothroydDewhurst method, Lucas Hull method and Hitachi Assembly Evaluation (AEM)
method. However, the selected method to be applied in this project is BoothroydDewhurst DFMA method.
2.4.1
What is DFMA?
The original definition of DFMA is the integration of manufacturing
considerations into the product design process. It is one of the most important tools
used by industrial engineers. Its basic objective is to reduce costs and increase
efficiency. DFMA also is an approach to improve product performance and to
simplify product.
DFMA consists of two distinct methodologies:
•
Design for Assembly (DFA)
•
Design for Manufacture (DFM)
which work together to develop a total product cost by optimizing the design using
the best materials and processes to meet customer functions at the lowest possible
cost. (G.Boothroyd & P.Dewhurts)
30
2.4.2
The Boothroyd-Dewhurst DFMA Approach
With DFMA, significant improvement tends to arise from simplicity thinking,
specifically reducing the number of standalone parts. The Boothroyd-Dewhurst DFA
methodology gives the following three criteria against which each part must be
examined as it is added to the assembly:
1.
During operation of the product, does the part move relative to all
other parts already assembled?
2.
Must the part be a different material than or be isolated form, all other
parts already assembled? Only fundamental reasons concerned with
material properties are acceptable.
3.
Must the part be separate from all other parts already assembled
because the necessary assembly or disassembly of other separate
parts would otherwise be impossible?
A “Yes” answer to any of these questions indicates that the part must be
separated or using DFA terminology, a critical part. All parts that are not critical, can
theoretically be removed or physically combine with other critical parts. Therefore,
theoretically, the number of critical parts is the minimum number of separate parts of
the design.
Next task is to estimate the assembly time for the design and establish its
efficiency rating in terms of assembly difficulty. This task can be done when each
part is checked to determine how it will be grasped, oriented, and inserted into the
product. From this exercise, the design is rated and from this rating standard time is
determined for all operations necessary to assemble the part. The DFA time standard
is a classification of design features which affect the assembly process. The total
assembly time can then be assessed, and using labor rate, the assembly costs and
efficiency can be estimated. At this stage, manufacturing costs are not considered, but
assembly time and efficiency provide benchmark for new iterations.
31
An analysis is carried out by using a design for assembly worksheet as shown
in Appendix 2C where, the examination of the handling and insertion time of each
part is referring to the tables of two-digit manual handling code and two-digit manual
insertion code as shown in Appendix 2D and Appendix 2E.
After all feasible simplification tasks are introduced, the next step is to
analyze the manufacture of the individual parts. The objectives of DFM are to select
the most suitable material and manufacturing process. Boothroyd-Dewhurst DFMA
methodology uses compatibility matrix for the processes and materials selection as
shown in Appendix 2F. In the selection of appropriate processes, the process
capabilities to manufacture a particular part shape are based upon the shape attributes
of the part. The attributes of the part are determined by the part geometric itself.
There are eight general shape attributes that need to be clearly understood
during applying the materials and processes selection. The shape attributes are:
1. Depressions (Depress)
-
The ability to form recesses or grooves in the surfaces of the part.
2. Uniform Wall (UniWall)
-
Uniform wall thickness.
3. Uniform Cross Section (UniSect)
-
Parts where any cross sections normal to a part axis are identical,
excluding draft.
4. Axis of Rotation (AxisRot)
-
Parts whose shape can be generated by rotation about a single axis: a
solid of revolution.
5. Regular Cross Section (ResXSec)
-
Cross sections normal to the part’s axis contain a regular pattern.
6. Captured Cavities (CaptCav)
-
The ability to form cavities with reentrant surface.
7. Enclosed (Enclosed)
-
Parts which are hollow and completely enclosed.
32
8. Draft Free Surface (NoDraft)
-
The capability of producing constant cross sections in the direction of
tooling.
Table of the shape generation capabilities for various processes are shown in
Appendix 2G. By referring to the table, the shape attributes with a “Yes” will
eliminate those processes that are not capable of producing these features. While,
those features with a “No” will eliminate those processes that are only capable of
producing part with these features present.
2.5
Summary
Value engineering has been successfully applied to the new product
development as the use of VE in NPD can provide high value products and services
to customers while simultaneously providing profits to the manufacturers and
suppliers. Besides that, TRIZ approach is a problem solving tool that had showed a
good result as it been integrated with various others problem solving tool which is
help them to solve contradiction problem. TRIZ is a logical, knowledge-based
methodology for early stages of the design process. Guided by TRIZ, users not only
overcome the psychological barrier but they also have the opportunity to analyze the
best direction for improvement of product.
CHAPTER 3
TRIZ – PROBLEM SOLVING PROCEDURE
3.1
Introduction
This chapter will explain about the tool that has been selected for the analysis
in this project which is Technical Contradiction Elimination – Inventive Principle
method. Technical Contradiction Elimination – Inventive Principle is one of the
several problem solving methods proposed by the TRIZ. The other methods are
Physical Contradiction Resolution/Separation Principle, Functional Improvement
Methods/TRIZ Standard Solutions, Complexity Reduction/Trimming, Evolution of
Technological Systems, and Physical, chemical and geometric effect based. Before
details about selected tool step by step process is explained, this chapter first shows
the general TRIZ process procedure.
34
3.2
General TRIZ Process Procedures
TRIZ has a four-step problem solving processes as shown in Figure 3.1. In
this process procedure, step two is where the problem solving tool, Technical
Contradiction Elimination – Inventive Principle method for this Master project is
selected.
Problem definition
Problem Classification & Problem Tool Selection
Problem Solution
Solution Generation
Figure 3.1: Four steps of TRIZ process procedure.
3.2.1
Problem definition
Problem definition is a very important step. The quality of the solution is
highly dependent on problem definition. The problem definitions start with several
general questions:
35
1. What is the problem?
2. What is the scope of the project?
3. What subsystem, system, and components are involved?
4. Do we have a current solution, and why is the current solution not good?
These are common questions to be asked in any engineering project. By
answering these questions, we are able to define the scope of the project and focus on
the right problem area. Besides answer these common questions, several TRIZ
methods are also very helpful in the problem definition stage.
i.
Functional modeling and functional analysis.
After identifying the project scope, it is very helpful to establish the functional
model of the subsystem involved in this project. Functional modeling and analysis
enables us to see the problem more clearly and precisely.
Subject
Action
Object
or Field
ii.
Ideality and ideal final result
After functional modeling and functional analysis, we can evaluate the
ideality of the current system by using
Ideality = ∑ benefit / ∑ costs + ∑ harm
Ideal final result means the ultimate optimal solution for current system in which;
∑ benefits → ∞
and
∑ costs + ∑ harm → 0
By comparing the ideality of the current system with idea final result, we can identify
“where the system improvement should go” and “what aspects of system should be
36
improved”. This will definitely help the problem definition and identify “what
problem should be solved”.
iii.
S-curve analysis.
It is very beneficial to evaluate the evolution stage of the current technical
system involved in any TRIZ project. For example, if our current subsystem is at
growth stage, then we should focus our attention to gradual improvement. If our
subsystem is near the maturity stage, then we will know that it is time to develop the
next generation of this subsystem.
iv.
Contradiction analysis
By using the method described in chapter 2, we can determine if there are any
physical contradictions or technical contradictions in our current system. TRIZ has
many methods to resolve contradictions.
3.2.2
Problem Classification and Tool Selection
In this step, problem solving tool will be selected regarding to the problem
definition that had been identify. After we are finished with the problem definition,
we should able to classify the problem into the following categories. For each
category there are many TRIZ methods available to resolve the problem.
i. Physical contradiction
Method : Physical contradiction resolution and separation principles.
ii. Technical contradiction
Method : Inventive principles.
37
iii. Imperfect functional structures
This problem occurs when there are inadequate useful functions or lack of
needed useful functions and when there are excessive harmful functions.
Method : Functional improvement methods and TRIZ standard solutions.
iv. Excessive complexity
This problem occurs when the system is too complex and costly, and some
of its functions can be eliminated or combined.
Method : Trimming and pruning.
v. System improvement
This problem occurs when the current system is doing its job, but
enhancement is needed to beat the competition.
Method : Evolution of technological systems.
vi. Develop useful functions
This problem occurs when we can identify what useful functions are
needed to improve the system but we do not know how to create these
functions.
Method : Physical, chemical, and geometric effect database.
3.2.3
Solution Generation
There are usually many TRIZ methods available for solving the problems
after problem classification. So many alternative solutions could be found. These
solutions will be evaluated in the next step.
38
3.2.4
Concept Evaluation
In this step, concept evaluation methods such as Pugh concept selection, value
engineering, and the axiomatic design method can be used to evaluate and select the
best solution.
3.2.5
TRIZ tool selection
From the view and research of the TRIZ tool to solve the problem in
designing product, the Technical Contradiction Elimination – Inventive Principle
method is selected. This is because this tool makes a decision based on the deleting
the contradiction occurred by considering the parameter that may affect and
principles that had to change in order to solve that problem.
3.3
Technical Contradiction Elimination – Inventive Principle Method
Figure 3.2 shows the four steps in applying this tool to solve problem in
designing the product for improvement. The first step is defined what are the
problems that occurred. After the problem had identified, the second step is to
formulate the problem. Then search for the previously well-solved problem and lastly
looks for analogous solution and adapt to the solution. In order to show how this tool
will be applied in this project, simple example will be used in this chapter which is
beverage can.
39
Figure 3.2: Technical Contradiction Elimina
Elimination – Inventive Principle step-by-step.
step
3.3.1
Step 1 – Identify the Problem
Boris Zlotin and Alla Zusman, principles TRIZ scientists at the American
company Ideation and students of Altshuller have developed an "Innovative Situation
Questionnaire" to identify the engineering system being studied, its operating
environment, resource
ce requirements, primary useful funct
function,
ion, harmful effects, and
ideal results. Table 3.1 show
shows the characteristic of the beverage can requirement for
improvement.
40
Table 3.1: Table characteristic of beverage can through Innovative Situation
Questionnaire.
Characteristic
Engineering system
To contain beverage
Operating environment
Cans are stacked for storage purpose
Resources requirement
Primary useful function
Harmful effect
Ideal result
3.3.2
What the thing
i.
ii.
iii.
Internal pressure of van
Weight of filled can
Rigidity of can construction
To contain beverage
i.
ii.
Cost of material and process
Waste of storage space
Can that can support the weight of stacking to
human weight without damage to can.
Formulate the Problem
Restate the problem in terms of physical contradictions. Identify problems
that could occur. Could improving one technical characteristic to solve a problem
cause other technical characteristics to worsen, resulting in secondary problems
arising? Are there technical conflicts that might force a trade-off? In the case of
beverage can, we cannot control the height to which cans will be stacked. The price
of raw materials compels us to lower costs. The can walls must be made thinner to
41
reduce costs, but if we make the walls thinner, it cannot support as large a stacking
load. Thus, the can wall needs to be thinner to lower material cost and thicker to
support stacking-load weight. This is a physical contradiction. If we can solve this,
we will achieve an ideal engineering system.
3.3.3
Previously Well-Solved Problem
Altshuller extracted from over 1,500,000 world-wide patents these 39
standard technical characteristics that cause conflict. These are called the 39
Engineering Parameters. Find the contradicting engineering principles. First find the
principle that needs to be changed. Then find the principle that is an undesirable
secondary effect. State the standard technical conflict.
In beverage can problem, the standard engineering parameter that has to be
changed to make the can wall thinner is "#4, length of a nonmoving object." In TRIZ,
these standard engineering principles can be quite general. Here, "length" can refer to
any linear dimension such as length, width, height, diameter, etc. If we make the can
wall thinner, stacking-load weight will decrease. The standard engineering parameter
that is in conflict is "#11, stress."
The standard technical conflict is: the more we improve the standard
engineering parameter "length of a nonmoving object," the more the standard
engineering parameter "stress" becomes worse.
3.3.4
Look for Analogous Solutions & Adapt To the Solution
Altshuller also extracted from the world wide patents 40 inventive principles.
These are hints that will help an engineer find a highly inventive (and patentable)
42
solution to the problem. Examples from patents are also suggested with these 40
inventive principles. To find which inventive principles to use, Altshuller created the
Table of Contradictions (Appendix 2A). The Table of Contradictions lists the 39
Engineering Parameters on the X-axis (undesired secondary effect) and Y-axis
(feature to improve). In the intersecting cells, are listed the appropriate Inventive
Principles to use for a solution.
The engineering parameters in conflict for the beverage can are "#4, length of
a nonmoving object" and "#11, stress." The feature to improve (Y-axis) is the can
wall thickness or "#4, length of a nonmoving object" and the undesirable secondary
effect (X-axis) is loss of load bearing capacity or "#11, stress." Looking these up on
the Table of Contradictions, we find the numbers 1, 14, and 35 in the intersecting
cell.
2
Weight of fixed object
3
Length of movable object
4
Length of fixed object
5
Area of movable object
10 1
29 35
8 15
29 34
2 17
29 4
35 30
13 2
7 17
4 35
13 4
8
35 8
2 14
7 14
17 4
29 30
4 34
8 10
18 37
8 10
19 35
17 10
4
28 10
10 36
47 40
13 29
10 18
1 8
35
1 14
35
10 15
36 28
19 30
35 2
Figure 3.3: Result for the problem. The inventive that should be considered are in the
red highlight numbers (Kai Yang and Basem, H. M.,2003).
Stress, pressure
Force
Speed
28
15 38
5 35
14 2
17 7
4 35
14 15
18 4
9
Volume of fixed object
8
29 2
40 28
15 17
4
35 28
40 29
Volume of movable
object
Area of fixed object
6
29 17
38 34
7
Area of movable object
Length of fixed object
4
5
Length of movable object
3
Weight of fixed object
2
15 8
29 34
11
Weight of movable object
10
1
Weight of movable object
What should
improved?
1
What is deteriorated?
43
Below are the details about the inventive principle which is what we have to do.
i.
Inventive Principle 1 is Segmentation
a. Divide an object into independent parts
b. Make an object sectional
c. Increase the degree of an object's segmentation
So that, for the beverage can cases, using Inventive Principle 1 c. "Increase
the degree of an object's segmentation," the wall of the can could be changed from
one smooth continuous wall to a corrugated or wavy surface made up of many "little
walls." This would increase the edge strength of the wall yet allow a thinner material
to be used. See Figure 3.4.
Figure 3.4: Cross section of corrugated can wall (Wikipedia-TRIZ, 2009).
ii.
Inventive Principle 14 is Spheroidality
a. Replace linear parts or flat surfaces with curved ones; replace
cubical shapes with spherical shapes
b. Use rollers, balls spirals
44
c. Replace a linear motion with rotating movement; utilize a
centrifugal force
Using Inventive Principle 14 a., the perpendicular angle at which most can
lids are welded to the can wall can be changed to a curve. See Figure 3.5.
Figure 3.5. Spheroidality Strengthens Can's Load Bearing Capacity. Perpendicular
angle has been replaced with a curve (Wikipedia-TRIZ, 2009).
.
iii.
Inventive Principle 35 is Transformation of the physical and
chemical states of an object.
a. Change an object's aggregate state, density distribution, degree of
flexibility, temperature
For beverage can case, we change the composition to a stronger metal alloy
used for the can wall to increase the load bearing capacity.
45
3.4
Summary
The inventive principle is the factors or things that we can refer it to do the
improvement and in the same time solve the problem occurred. As a conclusion, the
steps showed in this chapter will be used as a tool of this thesis case study. It will be
applied to the selected product case study together with the DFMA Methodology.
CHAPTER 4
PRODUCT CASE STUDY
4.1
Introduction
One of the “Product Design Improvement through VE and DFMA
Methodology” objectives is to select a consumer product as a case study. So that,
“Sponge Mop” had been chosen for this case study as illustrated in Figure 4.1. In this
Chapter 4, the product information, product assembly sequences, and function of each
part of the selected product will be shown.
47
4.2
Product as a Case Study
Technology has improved our everyday life vastly. It's changed so much from
how people lived just 50 years ago that it would be impossible to explain to someone
50 years ago what life is like today. Even, a simple product like mop also had been
through the several improvement stages until there are many types of mop, where
they are more easy to use now. Sponge mop is a cleaner device that basically used to
clean dirt on floor. There are two types of mop which are wet or dry mop. However,
in this case study, sponge mop which is classified under wet mop is used as a subject
to be studied.
4.2.1
Product Selection
The Sponge Mop chosen is the latest design of the mop in the market. It is
widely used by the household and also by the people that involve in cleaning job.
This sponge mop consists of fully mechanical part which creating a motion of the
wiper through the movement of handle that led others movement of part such a
pusher, arms and wiper holders. This sponge mop also has a sponge that can be put in
water with a detergent or other cleaner (under the general term surfactant) and rinsed
when cleaning is finished. Its head can be easily cleaned themselves and replaceable
when they begin to wear. There are several steps to use the sponge mop which are:
i.
The wiper is put into a water to make the wiper mild. Without water,
wiper can’t be squeeze because the material of wiper (sponge) will
become hard if it is dry.
ii.
Squeeze the wiper to remove the water by pulling the handle.
iii.
Start the cleaning process and squeeze the wiper when necessary.
48
The sponge mop that has been used in this case study is shown in Figure 4.1.
Figure 4.1: Sponge Mop.
4.2.2
Product Tree Structure
Product tree structure will show us the level of assembly for the product
where the number of level will determine the efficiency of the product assembly. In
order to minimize product assemble time, the number of level should be less. The
product tree structure for the sponge mop is shown in the Figure 4.2 which indicates
three levels of assembly.
Pin B
(2)
(4)
(1)
Legends:
Level 0
Level 2
Level 1
(1)
Handle
Bracket
(1)
Ring
(1)
Stopper
Figure 4.2: Sponge Mop product tree structure.
(2)
(2)
Screw B
(1)
Nut
(1)
(1)
Handle
Lock
Handle
(1)
Pusher L
Pusher R
Pusher
Nut
(1)
Pin A
(1)
Screw A
(2)
(2)
Joint
(1)
Wiper
Arm
Connector
Wiper
Holder
Head
Sponge Mop
(1)
Female
Adjuster
(1)
Male
Adjuster
Rod
(1)
Rod A
(1)
Rod B
49
(1)
Knob
50
4.2.3 Part ID Number
Each part of the sponge mop is assigned with an ID number presented by
assembly sequences. The sponge mop consists of 30 parts of total number of part and
21 parts different number of part. Table 4.1 illustrates the sponge mop part ID
number.
Table 4.1: The Sponge Mop part ID number.
Part ID
Part Name
Quantity
1
Connector
1
2
Screw A
1
3
Arm
2
4
Pin A
4
5
Wiper Holder
2
6
Joint
1
7
Pin B
2
8
Wiper
1
9
Rod A
1
10
Rod B
1
11
Male Adjuster
1
12
Female Adjuster
1
13
Stopper
1
14
Ring
1
15
Knob
1
16
Handle Bracket
1
17
Lock Handle
1
18
Screw B
2
19
Pusher R
1
20
Pusher L
1
21
Nut
3
Total part
30
51
4.2.4 Assembly Sequence
Assembly sequence is a sequence of the parts being assembled to become a
functional product. In this case, total of 30 parts being assembled to become one
functional sponge mop. Determination of the sequence is the early process that
should take into accounts. This is because from the assembly sequence, the difficulty
in the assembly process of the part can be defined. The assembly sequence of the
sponge mop is shown in Appendix 4.
4.3
Part Critique
The original part design of this sponge mop has their self function, strength
and weaknesses. Therefore, this part indicates about the each part of sponge mop
function, strength and weaknesses in an assembly point of view. Table 4.2 shows the
part critique for each part of sponge mop product.
52
Table 4.2: Part critique of each part for Sponge Mop
Part
ID
Picture
Part Name
Function
- To connect the
Head and Rod.
- To hold the
arms.
1
2
Remark
- Assembly time
higher because
of fastening part
using screw.
- Part not
symmetry,
increasing
handling and
insertion time.
Connector
- To tighten the
part.
- Require longer
time to fasten
part.
- As a movement
part for the
wiper holder.
- Provide squeeze
operation for the
wiper.
Screw A
- Require holding
down, not self
located.
3
Arm
- Part not
symmetry,
increasing
handling and
insertion time.
- To joint between
two parts.
4
Pin A
- Part is symmetry,
lower handling
and insertion
time.
- High assembly
time regarding to
the fit tolerance
between pin and
part to joint.
53
Table 4.2: Continued
Part
ID
Picture
Part Name
Function
- To hold the
wiper.
5
Remark
- Part not
symmetry,
increasing
handling and
insertion time.
Wiper Holder
- Require holding
down, part not
self located.
6
7
- As a joint device
for two wiper
holders.
- Part not
symmetry,
increasing
handling and
insertion time.
- To joint between
two parts.
- Part is symmetry,
lower handling
and insertion
time.
Joint
Pin B
- High assembly
time regarding to
the fit tolerance
between pin and
part to joint.
- To absorb water
for cleaning
purpose.
8
- Easy to dry
because the
material used is
polyurethane
foam.
Wiper
- To locate knob,
ring and stopper.
9
Rod A
- Easy to absorb
water.
- To hold the mop
during clean
operation.
- Very light
material.
54
Table 4.2: Continued
Part
ID
10
11
12
13
Picture
Part Name
Rod B
Function
- To locate Handle
sub assembly,
male adjuster
and female
adjuster.
- Very light
material.
- To adjust the
length of the
rod.
- Higher assembly
time regarding to
the thread
mechanism when
to fasten or
loosen the part.
- To adjust the
length of the
rod.
- Higher assembly
time regarding to
the thread
mechanism when
to fasten or
loosen the part.
- To stop the last
position of Rod
A.
- Make by harden
material and not
providing
cushion.
Male Adjuster
Female
Adjuster
Stopper
Remark
- Part not
symmetry.
- Part not
symmetry.
14
Ring
- As a cushion to
the Stopper.
- Part not
symmetry.
- Separate
assembly.
15
Knob
- As a gripping
purpose when
handling the
product.
- Very comfort to
grip.
55
Table 4.2: Continued
Part
ID
16
Picture
Part Name
Handle
Bracket
17
Lock Handle
Function
- To locate the
Lock Handle.
- The part is not
necessary as the
Handle can
directly assemble
with Rod B.
- To push and pull
Pusher for
squeezing the
wiper to remove
water.
- Good design
because provide
locking device.
18
Screw B
- To tighten the
part.
19
Pusher R
- To push and pull
Head
subassembly.
(right)
Remark
- Comfortable to
handle.
- Require longer
time to fasten part.
- Good in pulling
and pushing (very
strong).
20
Pusher L (left)
- To push and pull
Head
subassembly.
21
Nut
- To tighten the
part.
- Bad design
because using
more than one
pusher.
- Higher time in
assembly because
of treading
mechanism.
- Part is not
symmetry.
56
4.4
Summary
Sponge Mop had been chosen because it is a fully mechanical product which
is overall of its part can be easily disassembled and determined by using manual
DFA analysis. The process of disassemble had been done to determine the sequence
of product assembly process. Besides that, the function of each part also been
determined by the disassemble process. The total number of parts of sponge mop is
30 parts while the total number of different parts is 21 parts.
CHAPTER 5
DESIGN FOR ASSEMBLY (DFA) ANALYSIS FOR ORIGINAL
DESIGN
5.1
Introduction
This chapter discusses about the analysis result of the original design of
sponge mop that done by using Boothroyd Dewhurst DFMA approach. The
discussion will look into classification of each part for manual handling and insertion,
DFA worksheet analysis, estimated assembly time and cost, and also design
efficiency of the original design of sponge mop.
58
5.2
Classification of Product Parts
This section describes about the alpha (α) and beta (β) symmetry value for
each part of the sponge mop. Value of alpha and beta then will determine the two
digit manual handling and insertion code of each part. Determination of the two digit
code indicates the handling and insertion time for each part that which be used to
determine the operation time and cost of the product. Table 5.1 shows the analysis of
classification of product part for the original design.
Table 5.1: Classification of Part for Original Design
Part
Manual Handling
Manual
Manual
Alpha (α)
Beta (β)
Handling Code
Insertion Code
1.Connector
360º
180º
20
08
2.Screw A
360º
0º
10
38
3.Arm
180º
180º
10
08
4.Pin A
180º
0º
00
31
5.Wiper Holder
360º
360º
30
06
6.Joint
360º
180º
20
06
7.Pin B
180º
0º
00
31
8.Wiper
360º
180º
20
31
9.Rod A
360º
180º
20
00
10.Rod B
360º
0º
10
38
11.Male Adjuster
360º
0º
10
38
12.Female Adjuster
360º
0º
10
38
13.Stopper
180º
0º
10
32
14.Ring
360º
360º
30
30
15.Knob
360º
180º
20
30
16.Handle Bracket
360º
360º
30
30
17.Handle
360º
360º
30
06
18.Screw B
360º
0º
10
38
59
Table 5.1: Continued
Part
Manual Handling
Manual
Manual
Alpha (α)
Beta (β)
Handling Code
Insertion Code
19.Pusher R
360º
360º
30
31
20.Pusher L
360º
360º
30
31
21.Nut
360º
0º
10
38
5.3
Theoretical Minimum Part Assessment
The assessment of theoretical minimum part discusses the implementation of
the DFA principles by using the Q&A (question and answer) format for each part.
The assessments then will determine the value of the theoretical minimum number of
part, Nm. The value zero, 0 and one, 1 playing a vital role in consideration of
redesigning part. Besides being redesigned, the elimination of the part may be
occurred if the parts were not essential. The theoretical minimum part assessment
questions asked are as stated below:
i)
Does this part move relative to another?
ii)
Do the mating parts have to be making of different materials?
iii)
Do the parts have to be separate to allow servicing before or after
assembly?
60
5.4
DFA Worksheet
DFA worksheet will show the result of the analysis of the product, sponge
mop. In this section, the analysis is done for the original design of the sponge mop.
Table 5.2: DFA worksheet analysis for original design.
Estimation of theoretical
minimum # of parts, 0 or 1
9
Operation cost, cents,
0.1042 x (7)
8
Operation time, sec,
(2) x [(4) + (6)]
7
Manual insertion time per
part
6
Two-digit manual insertion
code
5
Manual handling time per
part
4
Two-digit manual handling
code
3
# of times the operation is
carried out consecutively
2
Part ID #
1
Name of Part
0
Connector
1
1
20
1.8
08
6.5
8.3
0.86486
1
Screw A
2
2
10
1.5
38
6
15
1.563
0
Arm
3
2
10
1.5
08
6.5
16
1.6672
2
Pin A
4
2
00
1.13
31
5
12.26
1.277492
0
Wiper
5
2
30
1.95
06
5.5
14.9
1.55258
2
Joint
6
1
20
1.8
06
5.5
7.3
0.76066
1
Pin B
7
4
00
1.13
31
5
24.52
2.554984
0
Wiper
8
1
20
1.8
31
5
6.8
0.70856
1
Rod A
9
1
20
1.8
00
1.5
3.3
0.34386
1
Rod B
10
1
10
1.5
38
1.5
3
0.3126
1
Male
11
1
10
1.5
38
6
7.5
0.7815
1
Holder
Adjuster
61
Table 5.2: Continued.
Estimation of theoretical
minimum # of parts, 0 or 1
9
Operation cost, cents,
0.1042 x (7)
8
Operation time, sec,
(2) x [(4) + (7)]
7
Manual insertion time per
part
6
Two-digit manual insertion
code
5
Manual handling time per
part
4
Two-digit manual handling
code
3
# of times the operation is
carried out consecutively
2
Part ID #
1
Name of Part
0
Female
12
1
10
1.5
38
6
7.5
0.7815
1
Stopper
13
1
10
1.5
32
4
5.5
0.5731
1
Ring
14
1
30
1.95
30
2
3.95
0.41159
0
Knob
15
1
20
1.8
30
2
3.8
0.39596
1
Handle
16
1
30
1.95
30
5
6.95
0.72419
0
Handle
17
1
30
1.95
06
5.5
7.45
0.77629
1
Screw B
18
1
10
1.5
38
6
7.5
0.7815
0
Pusher R
19
1
30
1.95
31
5
6.95
0.72419
1
Pusher L
20
1
30
1.95
31
5
6.95
0.72419
0
Nut
21
3
10
1.5
38
6
22.5
2.3445
0
194.93
20.3117
15
TM
CM
NM
Adjuster
Bracket
Total
62
5.5
Results
From the DFA worksheet analysis, the results of the estimated time, cost and
design efficiency of the assembly are obtained. Below are the summary of the result
for the original design analysis.
Total assembly time, TM = 194.93 secs.
Total assembly cost, CM = 20.3117 cents.
Theoretical minimum number of part, NM = 15
Design efficiency, DE = 23.09%
Note:
1) The value of total assembly cost (CM) is gained from the calculation below:
Value of labor cost per second (n) may vary due to different assumption and
for this case study, below n assumption is used.
-
Monthly salary for one operator = RM 600
-
Number of working day
= 20 days/month
-
Number of working hour/day
= 8 hours/day
So, labor cost per second, n
= RM 600 / (20 days x 8 hours x 3600secs)
= RM 0.001042/sec
= 0.1042 cents/sec
Thus, CM = TM x n
= 194.93 secs x 0.1042 cents/sec
= 20.3117 cents.
63
2) The design efficiency of the original design is gained by using below formula;
DE = 3 x NM x 100%
TM
= (3 x 15/ 194.93s) x 100%
= 0.2309 x 100%
= 23.09%
5.6
Summary
The analysis result of the original sponge mop had been showed through the
DFA worksheet analysis. From the design efficiency result, the product needs to be
improved because the value was categorized in less efficient. The design
improvements of the product Sponge Mop will be done based on analysis through
minimize the theoretical minimum number of parts and total assembly time.
CHAPTER 6
PROPOSED IMPROVEMENT OF NEW DESIGN USING
DFMA METHODOLOGY AND TRIZ CONCEPT
6.1
Introduction
This chapter discusses the proposed design improvement of the Sponge Mop.
There are two sections which are design improvement by using DFMA methodology
and design improvement using TRIZ concept. The detail of improvement also will
show in this chapter.
65
6.2
Improvement by Using DFMA Methodology.
Design improvement of product through DFMA Methodology is based on the
analysis of the important of part itself, part symmetry, difficulty in handling and also
difficulty in insertion of the part in assembly process.
6.2.1
Improvement 1: Connector
Figure 6.1 shows the original and new design of connector. There are four
features that had been improved to minimize the handling and insertion time. This
new connector is designed with sliding track that will guide the motion of the wiper
holders when wiper is squeezed inside. The sliding track will improve the motion of
wiper holders, and consequently eliminating the function of arms and pins. Flat end
features is designed to provide support and rigidity of wiper when consumers are
using this sponge mop. If it’s designed to be round or others shape that not flat, wiper
holder will freely moving and that will cause difficulties as the wiper holders are not
stacked during consumers used the sponge mop. Although handle is provided to
locking the wiper holders to its position, this flat end features will support the
function. Round features are designed to ease the motion of wiper holders when
wiper is squeezed. If these features are not provided, the motion of wiper holders will
stack and wiper cannot be squeezed. Locking hole is used together with snap fit shaft
to lock the connector with Rod A. This locking hole is designed slightly bigger that
the original sponge mop to locking the mating part rigidly.
This improvement had decrease the assembly time about 4.5 seconds. As
showed in Chapter 5, assembly time for original design connector is 8.3 seconds
while for this new design, the assembly time is only 3.8 seconds.
66
Original Design
New Design
Flat End
Round
Features
Locking Hole
Locking Hole
Sliding Track
Figure 6.1: Design improvement of connector.
6.2.2
Improvement 2: Wiper Holder
Figure 6.2 shows the original and new design of wiper holder. There are two
features that had been designed which are locking hole and slider. In original design
of sponge mop, the wiper holders was designed to be hold due to the parts is not
secured during assembly operation until pins were fixed to the hole. New design had
been made with concern to that problem. Thus new design is introduced to overcome
the problem. Now, locking hole is used together with ball plunger that had been
merged together with joint. Ball plunger is a standard part that can be easily got in
market. In new design, parts are assembled to joint without the part required to hold
down.
Assembly time by using this method is significantly reduced. Slider feature is
used to eliminate the function of pins in the original design and ensure the motion of
wiper holders is smooth. This improvement had decreased the assembly time about
19.26 seconds.
67
Original Design
New Design
Slider
Locking Hole
Pin Hole
Figure 6.2: Design improvement of wiper holder.
6.2.3
Improvement 3: Male Adjuster
Figure 6.3 is illustrating the new design of male adjuster. The new male
adjuster had been modified from the original design which switching the screwing
method to the snap fit features. This part is cannot be eliminated because it is
essential, thus modification to ease the insertion process is made. This mechanism is
similar to the mechanism that used on helmet at the locking device. By using this
method time for insertion is reduced.
This improvement had decreased the assembly time about 3.7 seconds. As
showed in Chapter 5, assembly time for original design male adjuster is 7.5 seconds
while for this new design, the assembly time is only 3.8 seconds.
68
Original Design
New Design
Thread
Snap Fit
Figure 6.3: Design improvement of Male Adjuster.
6.2.4
Improvement 4: Female Adjuster
Figure 5.5 shows the new design of female adjuster for sponge mop. Two
important features had been introduced which are snap fit feature and tapered feature.
This feature is very important in reducing assembly time and improving quality of
product. Snap fit method is used to simplify the assembly operation and also to
reduce the fastening time. It is because, in original design, method used is same as
screwing process. For tapered features, it was design to make a male adjuster tightly
gripping the Rod B.
This improvement had decreased the assembly time about 3.7 seconds. As
showed in Chapter 5, assembly time for original design female adjuster is 7.5 seconds
while for this new design, the assembly time is only 3.8 seconds.
69
Original Design
New Design
Snap Fit
Tapered
Figure 6.4: Design improvement of female adjuster.
6.2.5
Improvement 5: Stopper
Stopper is one of the important parts in sponge mop such indicated in Figure
6.5. Before this, stopper is used together with ring to provide limit of rod movement
and act as a cushion. This separate part will increase the time of assembly. Therefore,
ring is merged into stopper by designing stopper that will provide cushion function.
Material is uses as the material of stopper.
The combination of ring and stopper had decreasing assembly time of these
parts about 2.2 seconds. In the original design, assembly of these parts is 6 seconds
while it only taking 3.8 seconds in the new design assembly process.
70
Original Design
Stopper
New Design
Ring
Figure 6.5: Design improvement of Stopper.
6.2.6
Improvement 6: Rod A
Design of Rod A in a new design has a little bit different compare to the
original design. One feature had been added to the Rod A which is slot. Slot feature is
added to make the insertion of the stopper is easy because the assembly method
between Rod A and stopper had been changed to ease the assembly operation. In new
design, stopper is inserting to the Rod A without orientation by adding the slot
feature. Figure 6.6 is showing the Rod A of new design.
Original Design
New Design
Slot
Figure 6.6: Design improvement of Rod A.
71
6.2.7
Improvement 7: Handle
Figure 6.7 shows the handle design of new sponge mop. Generally, it shapes
is same to the original design. But one feature is added in order to simplify the
assembly method of sponge mop. The feature is slot. This slot is added because in the
new design, only one pusher is used and that pusher must be pivoted center to the
handle.
The assembly time of the new design resulted same value with the original
design which is 7.45 seconds. It means the two digits code for manual handling and
insertion remains constant.
Original Design
New Design
Slot
Figure 6.7: Design improvement of Handle.
6.2.8
Improvement 8: Joint
Figure 6.8 illustrates the new design of joint. In new design, three parts are
combined into one part which is two pins and joint. This new method is using ball
plunger which the ball plunger is a standard part. This improvement is dramatically
72
reduced the assembly operation because before this, joint is connected to others parts
using pins.
This improvement had decrease the assembly time about 3.5 seconds. As
showed in Chapter 5, assembly time for original joint is 7.3 seconds while for this
new design, the assembly time is only 3.8 seconds.
Original Design
New Design
Ball
Plunger
Figure 6.8: Design improvement of Joint.
6.2.9
Improvement 9: Snap Fit Shaft
Figure 6.9 shows the new fastener that replacing the screws and nuts.
Assembly time using this snap fit is reduced. This method is not affecting the
function of sponge mop because before this the function of screws is like a shaft that
allowing motion of other parts. Through this method, nuts is eliminated because the
operator just need to push this snap fit into hole position which the end features is
acting as a nut to prevent the shaft from dismantle.
73
Figure 6.9: New part design of Snap Fit Shaft.
6.2.10 Improvement 10: Pusher
In new design, only one pusher is used to push and pull the handle. Design
changes were in terms of size of the pusher and also its shape such indicated in
Figure 6.10. By using this pusher, time to assembly will dramatically reduced as it no
more using screws in its assembly.
The elimination of one pusher had reducing the time of assembly operation
about 9.95 seconds. In original design, time required is about 13.9 seconds while in
the new design the assembly time taken is about 3.95 seconds.
Figure 6.10: Improvement of Pusher quantity from two into one.
74
6.3
Improvement by Using TRIZ Concept
Design improvement through TRIZ concept is based on the solution that
given by the TRIZ itself. The solution is resulted from the contradiction problem
occurred during the improvement process by referring to the contradiction table of
inventive principles [Appendix 3].
6.3.1
Improvement 1: Pusher
Figure 6.11 shows the new design of Pusher after consideration with using
TRIZ concept. The problem with the old design of pusher sponge mop is it has two
pushers to pull the sponge mop wiper. Even though the performance is good however
it influences the rate of time and cost assembly of the part. So, in order to reduce the
time and cost of assembly, the used of only one pusher from two pushers is proposed.
Below is the TRIZ concept consideration to the problem occurred.
Improving parameter: Shape (Parameter 12)
Worsening parameter: Strength (Parameter 14)
Solutions : Principles 30, 14, 10 and 40
From the four principles suggested by the TRIZ solution, the principle 40 is
the suitable element in improving the part. Principle 40 proposed a solution about to
make the part from composite material. Composite material will hardened the
strength of the part evens the shape of part designed look like not giving enough
performance. So, the pusher has been designed like Figure 6.11, where the
combination of two pushers had eliminated one pusher of the Sponge Mop product.
75
Figure 6.11: New design of Pusher by combining two pushers into one.
6.3.2
Improvement 2: Male and Female Adjuster
Tread mechanism is known as the longest taking time in assembly process.
However, it also known as the mechanism for ease of maintenance as people will
easily open and close it. In this case, the elimination of the tread mechanism will
reduce the time taken to assembly the part. If in others improvement design tools, the
consideration of the effect of the improvement is overlook. But using TRIZ concept,
the effect that will occur during the improvement is measured. In this case, the
strength of the two part mate together will be less.
Improving parameter: Ease of operation (Parameter 33)
Worsening parameter: Strength (Parameter 14)
Solutions: Principles 32, 40, 3 and 28
The result from the TRIZ analysis shows that elements in Principle 32 and 40
can be used to improve the male and female adjuster. One of the elements in Principle
32 state that the problem can be solved by change the degree of translucency of an
object or processes which are difficult to see. In this part case study, the used of
transparency color of material will make the part ease of operation as it enable
operator to assemble it without intervention. Then, the Principle 40 will solve the
76
problem occur because of improvement parameter which is strength. Combination of
material or composite material makes the part more reliable then the part produce
using single material. Figure 6.12 shows the improvement of the Male and Female
Adjuster.
Lock Slot
Lock Leaf
(a)
(b)
Figure 6.12: (a) New design of male adjuster with lock leaf, and (b) New design of
female adjuster with lock slot.
6.3.3
Improvement 3: Joint
After several operation of the product, one of the parts which are pusher
started to damage the joint regarding the force given into it by the pusher. In order to
reduce the harmful effect caused by the pusher into joint, it required less force during
the operation. However, to maximize the product functionality, the high force is
required.
Improving parameter: Harmful action at object (Parameter 30)
Worsening parameter: Force (Parameter 10)
77
Solutions: Principles 13, 35, 39 and 18
The result from the TRIZ analysis shows that elements in Principle 13 and 35
can be used to reduce the harmful action at parts joint. One of the elements in
Principle 13 is invert the action used to solve the problem and in Principle 35 is
change the degree of flexibility. In this case, the idea is instead of using different
material between two objects (pusher and joint), change the joint material and
increase the flexibility of the joint into the same value flexibility of pusher. The
original joint is produce by using plastic material. So that, joint produced by using the
steel material same as the pusher is proposed.
6.3.4
Improvement 4: Wiper Holder, Connector, Arm and Pin
`
During the assembly process of the Sponge Mop, some of the parts look like
repeating the job that be done by other parts. It can be saw by the assemble parts
between wiper holder, pin, arm and connector. In this case, arm is not necessary as
the wiper holder still can be functioning without part of arm. However, in order to
reduce number of part in head area, the maintenance of the head area may more
difficult.
Improving parameter: Device complexity (Parameter 36)
Worsening parameter: Ease of repair (Parameter 34)
Solutions: Principles 1 and 13
The result from the TRIZ analysis shows that elements in Principle 1 and 13
can be used to reduce the ease of repair problem. In this case, the combination of one
element from each principle is be used to solve this problem. The element in
Principle 1 is make an object easy to disassemble while element in Principle 13 is
invert the action used to solve the problem. So, its means instead of using arm to
function the wiper holder, make the wiper holder function by its own. A new wiper
78
holder is functioning direct through the connector. The elimination of pin by make
the connector directly fit to wiper holder is an idea resulted from element in Principle
1. Figure 6.13 and Figure 6.14 show the result of new design of connector and wiper
holder.
Lock Pin
Figure 6.13: New design of connector based on idea from element in
Principle 1.
Pin Hole
Figure 6.14: New design of wiper holder that designing to fit with the new
connector design.
79
6.4
Summary
Through implementation of the DFMA Methodology and TRIZ Concept
several parts had been improved or been eliminated or combined. As a result, there
are ten improvements not excluded the elimination part had been determined through
DFMA analysis while the integrating of the TRIZ with DFMA had resulted six
improvements from the four problem design cases.
CHAPTER 7
DFMA AND TRIZ ANALYSIS FOR NEW DESIGN
7.1
Introduction
This chapter discusses about the analysis results for new design of sponge
mop. There two sections which are analysis result of new design using DFMA
methodology and analysis result of new design using TRIZ concept. It consist of
exploded view of the new design, bill of materials, justification and sketches of new
design, classification of each part for manual handling and manual insertion,
worksheet analysis, estimated assembly time and cost, and the new design
efficiency. Besides that, selection of materials and processes for a new designing
part of DFMA also will be explained in this chapter.
81
7.2
DFMA Analysis for New Design
This section will discusses about the analysis results of new sponge mop
design by using DFMA methodology. Figure 7.1 shows the new design of Sponge
Mop.
13
14
3
10
12
2
1
15
1
5
8
9
6
5
7
4
Figure 7.1: Exploded drawing of new design of Sponge Mop via DFMA
Methodology.
11
82
7.2.1
Classification of Product Parts
The implementation of the DFA methodologies had influenced the degree of
part symmetry as the consideration to make part easy to handle and insert are
measured. Low values of part symmetry degree will smaller two digits code for
manual handling and insertion time. Thus, it will result less value of time taken to
assembly the part. Table 7.1 shows the analysis of classification of product part for
the new design.
Table 7.1: Classification of Part for New Design by DFMA Methodology
Manual Handling
Alpha (α)
Beta (β)
1 (connector)
360o
180o
Manual
Handling
Code
20
2 (wiper Holder)
360o
360o
30
30
360
o
180
o
20
31
360
o
180
o
20
30
5 (Knob)
360
o
180
o
20
30
6 (Male Adjuster)
360o
180o
20
30
360
o
180
o
20
30
360
o
180
o
20
00
360
o
0
o
10
00
180
o
0
o
00
30
360
o
0
o
10
30
12 (Snap fit shaft 3)
360
o
0
o
10
30
13 (Handle)
360o
360o
30
06
360
o
360
o
30
30
360
o
180
o
20
30
Part
3 (Wiper)
4 (Female Adjuster)
7 (Stopper)
8 (Rod A)
9 (Rod B)
10 (Snap fit shaft 1)
11 (Snap fit shaft 2)
14 (Pusher)
15 (Joint)
Manual
Insertion
Code
30
83
7.2.2
Theoretical Minimum Parts Assessment
Basically, the value of theoretical minimum number of part for all part of
new design is one (1). This is because the analysis of new design required
elimination value of zero (0). However, it is doesn’t mean that the part can’t be
improve in the future. Others problem solving can be used is by joining or combined
two or more parts.
7.2.3
DFA Worksheet
DFA worksheet will show the result of the analysis of the product, sponge
mop. In this section, the analysis is done for the new design of the sponge mop by
using DFMA Methodology.
84
Table 7.2: DFA worksheet analysis for new design by DFMA methodology.
c5
c6
c7
c8
c9
2
3.8
0.39596
1
Add
2
30
1.95 30
2
7.9
0.82318
2
Add
1
20
1.8
30
2
3.8
0.39596
1
1
20
1.8
30
2
3.8
0.39596
1
1
20
1.8
30
2
3.8
0.39596
1
Add
Add and
snap Fit
Add
1
20
1.8
30
2
3.8
0.39596
1
Add
7(Stopper)
1
20
1.8
30
2
3.8
0.39596
1
8(Rod A)
9(Rod B)
10(Snap fit
shaft 1)
11(Snap fit
shaft 2)
12(Snap fit
shaft 3)
1
1
20
10
1.8
1.5
00
00
1.5
1.5
3.3
3
0.34386
0.3126
1
1
2
00
1.13 31
5
13
1.3546
2
1
10
1.5
30
2
3.5
0.3647
1
1
10
1.5
30
2
3.5
0.3647
1
13(Handle)
1
30
1.95 06
5.5
7.45
0.77629
1
14Pusher
1
30
1.95 30
2
3.95
0.41159
1
15(Joint)
1
20
1.8
2
3.8
0.39596
1
71.46
7.4461
17
TM
CM
NM
30
Estimation for
theoretical minimum
parts
30
Operation cost
(cent)
1.8
Operation time( sec)
20
1(connector)
2(wiper
Holder)
3(Wiper)
4(Female
Adjuster)
5(Knob)
6(Male
Adjuster)
Manual insertion time
per part
1
Part ID
Manual handling time
per part
c4
Manual handling code
c3
Manual insertion code
c2
Number of times the
operation is carried out
consecutively
c1
Total:
Name of
Assembly
Add and
Snap Fit
Add
Add
Add and
Snap Fit
Add and
Snap Fit
Add and
Snap Fit
Add and
Hold Down
Add and
Hold Down
Add and
Hold Down
Design
efficiency =
3 NM/TM=
71.37%
85
7.2.4
Results
From the DFA worksheet analysis, the results of the estimated time, cost and
design efficiency of the assembly are obtained. Below are the summary of the result
for the new design analysis.
Total assembly time, TM = 71.46 secs.
Total assembly cost, CM = 7.4461cents.
Theoretical minimum number of part, NM = 17
Design efficiency, DE = 71.37%
Note:
1) The value of total assembly cost (CM) is gained from the calculation below:
Value of labor cost per second (n) may vary due to different assumption and
for this case study, below n assumption is used.
-
Monthly salary for one operator = RM 600
-
Number of working day
= 20 days/month
-
Number of working hour/day
= 8 hours/day
So, labor cost per second, n
= RM 600 / (20 days x 8 hours x 3600secs)
= RM 0.001042/sec
= 0.1042 cents/sec
Thus, CM = TM x n
= 71.46 secs x 0.1042 cents/sec
= 7.4461cents.
86
2) The design efficiency of the original design is gained by using below
formula;
DE = 3 x NM x 100%
TM
= (3 x 17/ 71.46 s) x 100%
= 0.7137 x 100%
= 71.37%
7.2.5
DFM Analysis
Design for Manufacture (DFM) analysis is an analysis that conducted to
select the suitable material and manufacturing process for each part of product case
study. The result of analysis is determine by match out the part attributes of each
part with the table shape generation capabilities of processes [Appendix 2G] and
continuing by matching with the compatibility matrix for a final selection of
material and manufacturing process [Appendix 2F].
The part attributes of each part for a new design of Sponge Mop is shown in
Appendix 7A while Appendix 7B shows the final result of material and
manufacturing process of each part. From the overall result, thermoplastic material
and injection molding process are widely used in producing new design of Sponge
Mop.
87
7.3
TRIZ Analysis for New Design
This section will discuss about the analysis results of new sponge mop
design by using TRIZ concept. In this project case study, the analysis of design
efficiency of the product is done by applying DFA analysis. This is because for the
clear comparison purposes. Figure 7.2 shows the new design of Sponge Mop after
TRIZ elements are applying on it.
2
14
3
13
11
15
4
1
6
12
9
7
5
8
Figure 7.2: Exploded view of new design of Sponge Mop via TRIZ Concept.
88
7.3.1
Classification of Product Part
The implementation of the DFA methodologies had influenced the degree of
part symmetry as the consideration to make part easy to handle and insert are
measured. Low values of part symmetry degree will smaller two digits code for
manual handling and insertion time. Thus, it will result less value of time taken to
assembly the part. Table 7.3 shows the analysis of classification of product part for
the new design.
Table 7.3: Classification of Part for New Design by TRIZ Concept
Manual Handling
Part
Alpha (α)
Beta (β)
360o
180o
180
o
180
o
360
o
180
o
180
o
o
360
o
180
360
o
o
7 (Stopper)
360
o
8 (Rod A)
360o
1 (connector)
2 (wiper Holder)
3 (Wiper)
4 (Female Adjuster)
5 (Knob)
6 (Male Adjuster)
9 (Rod B)
11 (Snap fit shaft 2)
12 (Snap fit shaft 3)
13 (Handle)
14 (Pusher)
15 (Joint)
360
o
180
o
180
o
360
o
360
o
360
o
0
0
180
o
o
180o
0
o
0
o
0
o
360
o
360
o
180
o
Manual
Manual
Handling
Insertion
Code
Code
20
30
20
00
20
31
00
00
20
30
10
30
20
30
20
00
10
00
10
30
10
30
30
06
30
30
20
30
89
7.3.2
DFA Worksheet
DFA worksheet will show the result of the analysis of the product, sponge
mop. In this section, the analysis is done for the new design of the sponge mop by
using TRIZ concept.
Table 7.4: DFA worksheet analysis for new design by TRIZ.
c5
c7
c8
c9
3.8
0.39596
1
Add
2
20
1.8
00
1.5
6.6
0.68772
2
Add
1
20
1.8
30
2
3.8
0.39596
1
Add
1
00
1.13
00
1.5
2.63
0.27405
1
Add
1
20
1.8
30
2
3.8
0.39596
1
Add
1
10
1.5
30
2
3.5
0.36470
1
Add
7(Stopper)
1
20
1.8
30
2
3.8
0.39596
1
8(Rod A)
9(Rod B)
11(Snap fit
shaft 2)
12(Snap fit
shaft 3)
1
1
20
10
1.8
1.5
00
00
1.5
1.5
3.3
3
0.34386
0.31260
1
1
1
10
1.5
30
2
3.5
0.36470
1
1
10
1.5
30
2
3.5
0.36470
1
13(Handle)
1
30
1.95
06
5.5
7.45
0.77629
1
14Pusher
1
30
1.95
00
1.5
3.45
0.41159
1
15(Joint)
1
20
1.8
30
2
3.8
0.39596
1
55.93
5.8279
15
TM
CM
NM
Total:
Estimation for
theoretical minimum
parts
2
0.1042 x (c7)
30
Operation cost (cent)
1.8
(2) x [(4) + (6)]
20
1(connector)
2(wiper
Holder)
3(Wiper)
4(Female
Adjuster)
5(Knob)
6(Male
Adjuster)
Manual handling time
per part
1
Part ID
Operation time( sec)
c6
Manual insertion time
per part
c4
Manual insertion code
c3
Manual handling code
c2
Number of times the
operation is carried out
consecutively
c1
Name of
Assembly
Add and Snap
Fit
Add
Add
Add and Snap
Fit
Add and Snap
Fit
Add and Hold
Down
Add and Hold
Down
Add
Design efficiency
= 3 NM/TM=
80.46%
90
7.3.3
Results
From the DFA worksheet analysis, the results of the estimated time, cost and
design efficiency of the assembly are obtained. Below are the summary of the result
for the new improvement design of Sponge Mop by TRIZ concept analysis.
Total assembly time, TM = 55.93 secs.
Total assembly cost, CM = 5.8279 cents.
Theoretical minimum number of part, NM = 15
Design efficiency, DE = 80.46%
Note:
1) The value of total assembly cost (CM) is gained from the calculation below:
Value of labor cost per second (n) may vary due to different assumption and
for this case study, below n assumption is used.
-
Monthly salary for one operator = RM 600
-
Number of working day
= 20 days/month
-
Number of working hour/day
= 8 hours/day
So, labor cost per second, n
= RM 600 / (20 days x 8 hours x 3600secs)
= RM 0.001042/sec
= 0.1042 cents/sec
Thus, CM = TM x n
= 55.93 secs x 0.1042 cents/sec
= 5.8279 cents.
91
2) The design efficiency of the original design is gained by using below
formula;
DE = 3 x NM x 100%
TM
= (3 x 15/ 55.93 s) x 100%
= 0.8046 x 100%
= 80.46%
7.3.4
DFM Analysis
The part attributes of each part for a new design of Sponge Mop by TRIZ
concept analysis is shown in Appendix 7C while Appendix 7D shows the final result
of material and manufacturing process of each part. From the overall result, again
thermoplastic material and injection molding process are widely used in producing
parts for this new improvement design.
7.4
Summary
From the DFA analysis result, the values of both new improvement designs
are determined. Both design efficiency of the new design had improved the old
design efficiency. So, it means the objective of improvement is achieved.
CHAPTER 8
DISCUSSION
8.1
Introduction
This chapter discusses about the comparisons result between Sponge Mop
original designs with both new Sponge Mop improvement design. Besides that, the
differences result between both problem solving design tool also been discussed. As
state earlier, the problem solving design tools used in this case study are DFMA
methodology and TRIZ concept. However, in TRIZ concept it is more to integrating
the concept with the DFMA methodology. In this case study, TRIZ concept is
applying after DFMA methodology.
93
8.2
Comparisons of Product Case Study Result
This section consists of discussion about comparisons of DFMA analysis
result, comparisons of TRIZ analysis result, and comparisons between DFMA and
TRIZ improvement result.
8.2.1
Comparisons of DFMA Analysis Result
The comparisons of DFMA analysis result are based on the original design
and new design of Sponge Mop by applying Boothroyd-Dewhurst DFMA
Methodology. Table 8.1 shows the comparisons between original and new design.
Comparison of the items resulted effect of the improvement.
Table 8.1: Effect of the improvement.
Original
New
Percentage of Increment
Design
design
/Reduction
Number of Part
30
17
43.33% of reduction
Different Number of Part
21
15
28.57% of reduction
Total Assembly Time
194.93 s
71.46 s
63.34% of reduction
Total Assembly Cost
20.3117 cent
7.4461 cent 63.34% of reduction
Design Efficiency
23.09%
71.37%
Item
209.09% of increment
Table 8.1 indicates the effects of the improvements that had been made on the
original design of the sponge mop. The effects of the improvements were
dramatically viewed especially in the design efficiency. The value of 209.09%
increment shows that the implementing of Boothroyd-Dewhurst DFA methodology in
product design will ensure in increasing the design efficiency of a product. From the
table, it clearly shows that the increment of design efficiency is influence by the
94
achievement on reducing the number of part and assembly time of the product case
study. Besides that, the achievement on reducing number of part and assembly time
had reducing the cost to assemble the new design of product case study.
High percentage improvement is achieved in reducing the total assembly time
compared to the percentage improvement of number of part which is only 28.57%.
So, it’s shows that even the improvement of product can’t be improve through
reducing the number of part, the improvement can be done by simplifying the part of
the product such as make the part symmetry, design the part to easy to handle and
insertion.
Table 8.2 shows the effects of design changes in terms of time saving.
Basically, time saving is slightly due to the two concerns when conducting
Boothroyd-Dewhurst DFA analysis which are by combining and eliminating the
parts. However, simplified the assembly process also will resulted the time saving.
Table 8.2: Result of time saving due to the factor of design change.
No
1
2
3
4
Design Change
Connector (eliminated arms
and pins)
Eliminate one pusher, handle
bracket, ring,
Redesign wiper holders, female
and male adjuster, stopper, Rod
A, handle, and joint.
Eliminating screws and nuts
Items
Time Saving (s)
1, 3, 7
45.02
14, 16, 19,
17.85
5, 6, 9, 11,
12, 13, 17
17.65
2, 18, 21
28.5
From the Table 8.2, the major contributor of time saving for the new design of
Sponge Mop is by redesign the connector part. The new design of connector had
eliminated the used of arms and pins as from the DFA evaluation, these two parts is
not necessary which means the connector can operate by itself. In this case study, the
connector had been redesign (refer Chapter 6) to directly attached to the wiper part.
The next design factors that contributing in time saving is the elimination of screws
95
and nuts by proposing snap fit mechanism. This elimination totally resulted high
saving time as assembly time of screw and nut are the highest compared to others
mating mechanism.
8.2.2
Comparisons of TRIZ Analysis Result
The discussion on the comparisons of TRIZ analysis result in this section is
more on the improvement process that had been done on the part of product case
study. If in the DFMA, quantitative is the main consideration however in TRIZ, the
qualitative becoming the main consideration. Besides that, the different value of time
assembly also will be discussed. Table 8.3 shows the effect of the improvement
result.
Table 8.3: Effect of the improvement result.
Item
Pusher
Description
Improvement
Remark
The aim is to reduce Eliminate one pusher by The improvement
the number of pusher. combining
In
original
the
two through TRIZ had
design, pushers. The new design reduced assembly
two pushers are used still remains the same about 0.5 seconds
to make the product strength
function.
with
the
However, design. The used of pin
the strength of the also be eliminated.
part
should
constant.
old from the DFMA.
be
96
Table 8.3: Continued.
Item
Male and
Description
Improvement
The aim is to make Changing
operation
Remark
threading The
improvement
of mechanism into snap clip through TRIZ had
Female
the
Adjuster
assembly more easily mechanism.
The
new reduced
assembly
but in the same time mechanism remains the about 0.47 seconds
the strength of mating strength. The transparent from
parts
should
ever color of material is used in The
order
lasted.
the
to
make
DFMA.
qualitative
the value of part is also
assembly operation more improved.
easily.
Joint
The consideration of No improvement in terms The improvement of
joint is to reduce the of
design
done. this
is
part
harmful effect make However, improvement is influencing
by pusher. However, done
by
changing
not
the
the assembly time but in
the force required by material of the joint same terms of the quality
pusher to make the as
product
material
functioning Same
can’t be less.
material
of
pusher. of the part.
characteristic
will
less
possibility to damage.
of
the
97
Table 8.3: Continued.
Item
Description
Improvement
Wiper
The aim of these parts Arms
Holder,
is
to
reduce
are
The improvement
by
through TRIZ had
part. redesigning the wiper
reduced assembly
the eliminated
Connector,
number
Arms and
However, elimination holder and
Pins
of
and
pins
Remark
connector
about 1.7 seconds
of part may disturb part. Both improvement
from the DFMA.
the
ease
of parts are directly being
maintenance of other assembled together and
parts.
the improvements are
not influenced process
of maintenance for joint
part.
In
DFMA,
the
maintenance process
of joint will make
the wiper separated
from connector and
required
down
holding
during
insertion
assembly process.
of
98
8.2.3
Comparisons between DFMA and TRIZ Improvement Result
This section will discuss about the effect of the improvement of integrating
the DFMA methodology and TRIZ concept. The improvement is compared with the
analysis done by the DFMA methodology alone. Table 8.4 shows the comparisons
between DFMA new design analysis result and integrating DFMA and TRIZ analysis
results.
Table 8.4: Effect of the improvement
DFMA +
Different
TRIZ
Percentage
17
15
11.76% of reduction
Total Assembly Time
71.46 s
55.93 s
21.73% of reduction
Total Assembly Cost
7.4461 cents
5.8279 cents
21.73% of reduction
Design Efficiency
71.37%
80.46%
12.74% of increment
Item
DFMA
Theoretical
Minimum
Number of part
From the Table 8.4, the results showed that the analysis result done by the
integrating two design problem solving tools gave a high improvement percentage
compared to the analysis done by DFMA Methodology only. The integration tools
had minimized the theoretical minimum number of part into 15 parts with percentage
of reduction from the new design DFMA analysis is equal to 11.76%.
Besides that, the integrating two design problem solving tools also resulted in
the achievement to reduce the product assembly time and cost. The achievement had
resulted 21.73% of reduction from the new design DFMA analysis. Lastly, the result
showed that the integration of DFMA and TRIZ had increased the design efficiency
of the new Sponge Mop into 80.46%. It means that the qualitative factor influenced
99
the value of the design efficiency percentage. The increasing result, dramatically
affect the improvement by 12.74% of increment.
Even though the percentage of improvements is low, the objective to show
that integrating problem solving tools will give more impact in term of result is
achieved.
8.3
Summary
In summary, the used of integrating DFMA methodology and TRIZ concept
in the improvement product stage will give more value added to the result. This is
because, TRIZ not only giving benefit in term of quantitative but also in term of
qualitative. However, the other conclusion can be done is the application of
Boothroyd-Dewhurst DFMA methodology dramatically will increase the value of
product design efficiency in term of assembly process.
CHAPTER 9
CONCLUSION
9.1
Introduction
This chapter concluded the thesis case study. Besides that, future work
recommendation also will be highlighted in this chapter.
From the study that had been done, the objective to integrate Theory of
Inventive Problem Solving (TRIZ), and Design for Manufacture and Assembly
(DFMA) methodology in order to improve the design of consumer product has been
met. TRIZ concept by using contradiction philosophy had been selected because it
shows the ways how one factor needs to be considered if another factor is going to be
changed and the result shows the used of integrating DFMA and TRIZ really give a
better result compared to use only one design problem solving tool.
101
9.2
Recommendations for Future Work
In this thesis, the improvement of product design is proposed by integrating
DFMA and TRIZ, where the application of TRIZ had booster the DFMA analysis
result. So, it had proved that integration of more than one design problem solving tool
will resulted better result. However, in this thesis, the application of TRIZ tool is not
fully utilized as it had been constrain by the product case study selected and also time
to explore it. Below are the several recommendations for future work:
1. Integrate TRIZ with other design analysis methodology or design problem
solving tool such as Design for Robustness (DFR) as our technology now
a days is going for this area. Robust design is a set of engineering methods
for
attaining
high-quality
function
despite
variations
due
to
manufacturing, the environment, deterioration, and customer use patterns.
The fundamental principle of robust design is to improve the quality of the
product by minimizing the effects of variation without eliminating the
causes [Phadke, 1989]. The methodology that was used is similar to that
employed by Altshuller [1984] in developing TRIZ. Altshuller screened
several patents looking for inventive problem and how they were solved.
He ultimately came to the conclusion that patents can be best classified on
the basis of how they overcome contradictions in previously existing
engineering systems. It was found that Altshuller’s research approach to
be of great value. This research approach is composed of four steps:
a. Collect a large body of inventions related to robustness.
b. Analyze the inventions in detail to understand how they achieved
improved robustness.
c. Seek useful classification principles for the inventions.
d. Develop a database organized around the classification principles.
102
2. Integration of the TRIZ and DFMA by utilizing other additional TRIZ tool
where more difficult problems are solved with this more precise tool
which is the application of ARIZ (Algorithm for Inventive Problem
Solving).
ARIZ is a systematic procedure for identifying solutions
without apparent contradictions. Depending on the nature of the problem,
anywhere from five to sixty steps may be involved. From an unclear
technical problem, the underlying technical problem can be revealed. Can
be used with levels two, three, and four problems. Basic steps included:
a. Formulate the problem.
b. Transform the problem into a model.
c. Analyze the model.
d. Resolve physical contradiction.
e. Formulate ideal solution.
3. The other recommendation is to integrate more than two design problem
solving tools to make an improvement of a product. One of the
suggestions is to integrate between QFD, TRIZ and FMEA in conceptual
design for product development process.
103
9.3
Concluding Remark
As a conclusion, TRIZ is a systematic methodology for product simplification
which is the problem solving is based on guidelines not try and error. In other word,
TRIZ proposed ‘how to solve’ not ‘what to solve’. TRIZ will create potential design
solutions, resolve design contradiction and increase design option.
The integration of DFMA methodologies with TRIZ had helped a lot in
reducing the number of parts in a design improvement. By reducing the number of
parts, the assembly time and costs are significantly reduced. Besides that, the DFA
guidelines are very valuable information in the design improvement process. While,
DFM analysis selected the best material and manufacturing process for the
component parts of the assembly.
105
REFERENCES
1.
Lucchetta, G., Bariani, P. F., Knight. W. A., Integrated Design Analysis for
Product Simplification. University of Padova, Italy.
2.
Triz-journal.com. Utilization of TRIZ with DFMA to Maximize Value [Online].
Available: http://www.triz-journal.com. [2009, July 21]
3.
Wikipedia. Value Engineering [Online]. Available:
http://en.wikipedia.org/wiki/Value_engineering. [2009, July 9]
4.
Wikipedia. TRIZ [Online]. Available: http://en.wikipedia.org/wiki/TRIZ. [2009,
July 20].
5.
Darell. L. Mann. Integration and Application of TRIZ and DFMA. Systematicinnovation.com. 2002.
6.
Kai Yang., Basem, E.H. Design for Six Sigma – A Roadmap for Product
Development. New York: McGraw-Hill. 2003.
7.
Altshuller, G. and Henry. The Art of Inventiving (And Suddenly the Inventor
Appeared). Technical Innovation Center. 1994.
8.
Rajesh. J., Philip. S. Design for Six Sigma – A Holistic Approach to Design and
Innovation. New Jersey: Wiley. 2008.
9.
Boothroyd, G . and Dewhurst, P. Product Design for Manufacture and
Assembly. New York: Marcel Dekkel. 2002.
10.
Zhongsheng Hua, Jie Yang, Solomani Coulibaly, and Bin Zhang. Integration
TRIZ with Problem Solving Tools: A Literature Review From 1995 to 2006.
International Journal Business Innovation and Research, Vol 1. 2006.
11. Triz-journal.com (2009). Innovation; The next Frontier for Six Sigma [Online].
Available: http://www.triz-journal.com. [2009, July 27]
106
12. Chung-Shing, W. and Teng-Ruey, C. Integrated QFD, TRIZ and FMEA in
Conceptual Design for Product Development Process. Proceedings of the 13th
Asia Pacific Management Conference. Melbourne, Australia: APMR. 2007.
1085-1095.
13. Ideationtriz.com. Ideation/TRIZ: Innovation Key to competitive Advantage and
Growth [Online]. Available:
http://www.ideationtriz.com/paper_ITIRZ_Innovation_Key.htm. 2009.
14. Daniela, S., Elena, M., Nicolae, I. and Thomas, R. A TRIZ Approach to Design
for Environment. Galway Mayo Institute of Technology. Unpublished.
15. Darell. L. Mann. Beyond Systematic Innovation: Integration of Emergence
and Recursion Concepts into TRIZ and Other Tools. Systematicinnovation.com. 2002.
16.
Valery, K., Jun-Young, L. and Jeong-Bai, L. TRIZ Improvement of Rotary
Compressor Design. Proceedings of TRIZCON2005, the annual conference of
the Altshuller Institute, Brighton, MI USA: 2005.
17.
Noel, L. R. A Proposal to Integrate TRIZ into the Design Product Process
[Online]. Available: http://www.trizjournal.com/archives/2002/11/b/index.htm. 2002.
18.
Masaya, T. and Manabu, S. The Possibility of VE Activities as New Product
Planning by Utilizing TRIZ Techniques. The SANNO Institute of Management,
Tokyo, Japan.
19.
Ahmad Humaizi Bin Hilmi. Design and Analysis of a Paintball Marker Using
Boothroyd-Dewhurst DFMA Methodology. Master Thesis. Universiti
Teknologi Malaysia; 2005.
20.
Noor Laili Binti Ali, Design for Assembly: Design Improvements for
Assembled Product Using Boothroyd-Dewhurst DFMA Methodology. Bachelor
Project Thesis. Universiti Teknologi Malaysia: 2009.
107
21.
Chong Teik Seng, Development of the Prototype System for Design for
Assembly (DFA) Using Boothroyd-Dewhurst DFMA Methodology. Bachelor
Project Thesis. Universiti Teknologi Malaysia: 2006.
22.
Baizura Binti Zubir @ Zubair. Assemblability Design Effieciency (ADE)
Analyses for Design for Automatic Assemblies (DFAA). Master Thesis.
Universiti Teknologi Malaysia; 2008.
108
APPENDICES
Writing report
Oral Presentation 1
Submit draft report
Evalute the new design (apply
DfMA only)
Propose improvement
Identify and select possible
solution
Evaluate original product design
Select consumer product
Literature Review on Value
Engineering, DfMA and TRIZ
Methodology
Select Project Title
PROJECT ACTIVITIES
A
P
P
A
A
P
A
P
A
P
A
P
A
P
A
P
A
P
A
P
Week 12
Week 11
Week 10
Week 9
Week 8
Week 7
Week 6
Week 5
Week 4
Week 3
Week 2
Week 1
APPENDIX 1A - GANTT CHART 1: PROJECT ACTIVITIES FOR MASTER PROJECT PART 1
Week 15
Week 14
Week 13
109
Writing report
Oral Presentation 2
Submit draft report
Discussion and conclusion
Analysis the overall project
Evalute the new design (apply
DfMA & TRIZ)
Evalute the new design (apply
DfMA only)
Propose improvement
PROJECT ACTIVITIES
A
P
A
P
A
P
A
P
A
P
A
P
A
P
A
P
Week 12
Week 11
Week 10
Week 9
Week 8
Week 7
Week 6
Week 5
Week 4
Week 3
Week 2
Week 1
APPENDIX 1B - GANTT CHART 2 PROJECT ACTIVITIES FOR MASTER PROJECT PART 2
Week 15
Week 14
Week 13
110
111
APPENDIX 2A – CONTRADICTION TABLE OF 39 PARAMETERS
112
113
114
115
116
117
APPENDIX 2B – THE 40 INVENTIVES PRINCIPLES
1.
Segmentation
a. Divide an object into independent parts
b. Make an object sectional
c. Increase the degree of an object's segmentation
Examples:
2.
•
Sectional furniture, modular computer components, folding wooden ruler
•
Garden hoses can be joined together to form any length needed
Extraction
a. Extract (remove or separate) a "disturbing" part or property from an object,
or
b. Extract only the necessary part or property
Example:
•
To frighten birds away from the airport, use a tape recorder to reproduce
the sound known to excite birds. (The sound is thus separated from the
birds.)
3.
Local Quality
a. Transition from a homogeneous structure of an object or outside
environment/action to a heterogeneous structure
b. Have different parts of the object carry out different functions
c. Place each part of the object under conditions most favorable for its
operation
Examples:
•
To combat dust in coal mines, a fine mist of water in a conical form is
applied to working parts of the drilling and loading machinery. The
smaller the droplets, the greater the effect in combating dust, but fine mist
118
hinders the work. The solution is to develop a layer of coarse mist around
the cone of fine mist.
•
4.
A pencil and eraser in one unit.
Asymmetry
a. Replace a symmetrical form with an asymmetrical form.
b. If an object is already asymmetrical, increase the degree of asymmetry
Examples:
•
Make one side of a tire stronger than the other to withstand impact with
the curb
•
While discharging wet sand through a symmetrical funnel, the sand forms
an arch above the opening, causing irregular flow. A funnel of
asymmetrical shape eliminates the arching effect.
5.
Combining
a. Combine in space homogeneous objects or objects destined for contiguous
operations
b. Combine in time homogeneous or contiguous operations
Example:
•
The working element of a rotary excavator has special steam nozzles to
defrost and soften the frozen ground.
6.
Universality
Have the object perform multiple functions, thereby eliminating the need for
some other object(s).
Examples:
•
Sofa which converts into a bed
•
Minivan seat which adjusts to accommodate seating, sleeping or carrying
cargo.
119
7.
Nesting
a. Contain the object inside another which, in turn, is placed inside a third
object
b. Pass an object through a cavity of another object
Examples:
8.
•
Telescoping antenna
•
Chairs which stack on top of each other for storage
•
Mechanical pencil with lead stored inside
Counterweight
a. Compensate for the object's weight by joining with another object that has a
lifting force
b. Compensate for the weight of an object by interaction with an environment
providing aerodynamic or hydrodynamic forces
Examples:
•
Boat with hydrofoils.
•
A rear wing in racing cars which increases pressure from the car to the
ground.
9.
Prior counter-action
a. Perform a counter-action in advance.
b. If the object is (or will be) under tension, provide anti-tension in advance.
Examples:
•
Reinforced concrete column or floor.
•
Reinforced shaft made from several pipes which have been previously
twisted to some specified angle.
10.
Prior action
a. Carry out all or part of the required action in advance
b. Arrange objects so they can go into action in a timely matter and from a
convenient position
Examples:
120
•
Utility knife blade made with a groove allowing the dull part of the blade
to be broken off, restoring sharpness
•
Rubber cement in a bottle is difficult to apply neatly and uniformly.
Instead, it is formed into a tape so that the proper amount can be more
easily applied.
11.
Cushion in advance
Compensate for the relatively low reliability of an object by countermeasures
taken in advance.
Example:
•
12.
Merchandise is magnetized to deter shoplifting.
Equipotentiality
Change the working conditions so that an object need not be raised or
lowered.
Example:
•
Automobile engine oil is changed by workers in a pit to avoid using
expensive lifting equipment
13.
Inversion
a. Instead of an action dictated by the specifications of the problem,
implement an opposite action
b. Make a moving part of the object or the outside environment immovable
and the non-moving part movable
c. Turn the object upside-down
Example:
•
14.
Abrasively cleaning parts by vibrating the parts instead of the abrasive
Spheroidality
a. Replace linear parts or flat surfaces with curved ones; replace cubical
shapes with spherical shapes
b. Use rollers, balls spirals
121
c. Replace a linear motion with rotating movement; utilize a centrifugal force
Example:
•
Computer mouse utilized ball construction to transfer linear two-axis
motion into vector motion
15.
Dynamicity
a. Make an object or its environment automatically adjust for optimal
performance at each stage of operation
b. Divide an object into elements which can change position relative to each
other
c. If an object is immovable, make it movable or interchangeable
Examples:
•
A flashlight with a flexible gooseneck between the body and the lamp
head
•
A transport vessel with a cylindrical-shaped body. To reduce the draft or a
vessel under full load, the body is comprised of two hinged, halfcylindrical parts which can be opened.
16.
Partial or overdone action
If it is difficult to obtain 100% of a desired effect, achieve somewhat more or
less to greatly simplify the problem.
Examples:
•
A cylinder is painted by dipping into paint, but contains more paint than
desired. Excess paint is then removed by rapidly rotating the cylinder.
•
To obtain uniform discharge of a metallic powder from a bin, the hopper
has a special internal funnel which is continually overfilled to provide
nearly constant pressure.
17.
Moving to a new dimension
a. Remove problems with moving an object in a line by two-dimensional
movement (i.e. along a plane)
122
b. Use a multi-layered assembly of objects instead of a single layer
c. Incline the object or turn it on its side
Example:
•
A greenhouse which has a concave reflector on the northern part of the
house to improve illumination of that part of the house by reflecting
sunlight during the day.
18.
Mechanical vibration
a. Set an object into oscillation
b. If oscillation exists, increase its frequency, even as far as ultrasonic
c. Use the resonant frequency
d. Instead of mechanical vibrations, use piezovibrators
e. Use ultrasonic vibrations in conjunction with an electromagnetic field
Examples:
•
To remove a cast from the body without injuring the skin, a conventional
hand saw was replaced with a vibrating knife.
•
Vibrate a casting mold while it is being filled to improve flow and
structural properties.
19.
Periodic action
a. Replace a continuous action with a periodic (pulsed) one.
b. If an action is already periodic, change its frequency.
c. Use pulsed between impulses to provide additional action.
Examples:
•
An impact wrench loosens corroded nuts using impulses rather than
continuous force.
•
A warning lamp flashes so that it is even more noticeable than when
continuously lit.
123
20.
Continuity of a useful action
a. Carry out an action continuously (i.e. without pauses), where all parts of an
object operate at full capacity.
b. Remove idle and intermediate motions.
Example:
•
A drill with cutting edges which permit cutting in forward and reverse
directions.
21.
Rushing through
Perform harmful or hazardous operations at very high speed.
Example:
•
A cutter for thin-walled plastic tubes prevents tube deformation during
cutting by running at a very high speed (i.e. cuts before the tube has a
chance to deform).
22.
Convert harm into benefit
a. Utilize harmful factors or environmental effects to obtain a positive effect.
b. Remove a harmful factor by combining it with another harmful factor.
c. Increase the amount of harmful action until it ceases to be harmfull.
Examples:
•
Sand or gravel freezes solid when transported through cold climates. Overfreezing (using liquid nitrogen) makes the ice brittle, permitting pouring.
•
When using high frequency current to heat metal, only the outer layer became
hot. This negative effect was later used for surface heat-treating.
23.
Feedback
a. Introduce feedback.
b. If feedback already exists, reverse it.
Examples:
124
•
Water pressure from a well is maintained by sensing output pressure and
turning on a pump if pressure is too low.
•
Ice and water are measured separately but must combine to total a specific
weight. Because ice is difficult to dispense precisely, it is measured first.
The weight is then fed to the water control device, which precisely
dispenses the needed amount.
24.
Mediator
a. Use an intermediary object to transfer or carry out an action.
b. Temporarily connect an object to another one that is easy to remove.
Example:
•
To reduce energy loss when applying current to a liquid metal, cooled
electrodes and intermediate liquid metal with a lower melting temperature
are used.
25.
Self-service
a. Make the object service itself and carry out supplementary and repair
operations
b. Make use of wasted material and energy
Examples:
•
To prevent wear in a feeder which distributes an abrasive material, its
surface is made from the abrasive material
•
In an electric welding gun, the rod is advanced by a special device. To
simplify the system, the rod is advanced by a solenoid controlled by the
welding current.
26.
Copying
a. Use a simple and inexpensive copy instead of an object which is complex,
expensive, fragile or inconvenient to operate.
b. Replace an object by its optical copy or image. A scale can be used to
reduce or enlarge the image.
125
c. If visible optical copies are used, replace them with infrared or ultraviolet
copies.
Example:
•
27.
The height of tall objects can be determined by measuring their shadows.
Inexpensive, short-lived object for expensive, durable one
Replace an expensive object by a collection of inexpensive ones, forgoing
properties (e.g. longevity)
Examples:
•
28.
Disposable diapers.
Replacement of a mechanical system
a. Replace a mechanical system by an optical, acoustical or olfactory (odor)
system.
b. Use an electrical, magnetic or electromagnetic field for interaction with the
object.
c. Replace fields
1. Stationary fields with moving fields.
2. Fixed fields with those which change in time.
3. Random fields with structured fields.
d. Use a field in conjunction with ferromagnetic particles.
Example:
•
To increase the bond between metal coating and a thermoplastic material,
the process is carried out inside an electromagnetic field which applies
force to the metal.
29.
Pneumatic or hydraulic construction
Replace solid parts of an object by gas or liquid. These parts can use air or
water for inflation, or use air or hydrostatic cushions.
Examples:
126
•
To increase the draft of an industrial chimney, a spiral pipe with nozzles
was installed. When air flows through the nozzles, it creates an air-like
wall, reducing drag.
•
For shipping fragile products, air bubble envelopes or foam-like materials
are used.
30. Flexible membranes or thin film
a. Replace traditional constructions with those made from flexible membranes
or thin film.
b. Isolate an object from its environment using flexible membranes or thin
film.
Example:
•
To prevent water evaporation from plant leaves, polyethylene spray was
applied. After a while, the polyethylene hardened and plant growth
improved, because polyethylene film passes oxygen better than water
vapor.
31.
Use of porous material
a. Make an object porous or add porous elements (inserts, covers, etc.).
b. If an object is already porous, fill the pores in advance with some
substance.
Example:
•
To avoid pumping coolant to a machine, some of its parts are filled with a
porous material soaked in coolant liquid. The coolant evaporates when the
machine is working, providing short-term uniform cooling.
32.
Changing the color
a. Change the color of an object or its surroundings.
b. Change the degree of translucency of an object or processes which are
difficult to see.
127
c. Use colored additives to observe objects or processes which are difficult to
see.
d. If such additives are already used, employ luminescent traces or tracer
elements.
Examples:
•
A transparent bandage enabling a wound to be inspected without
removing the dressing.
•
A water curtain used to protect steel mill workers from overheating
blocked infrared rays but not the bright light from the melted steel. A
coloring was added to the water to create a filter effect while preserving
the transparency of the water.
33.
Homogeneity
Make those objects which interact with a primary object out of the same
material or material that is close to it in behavior.
Example:
•
The surface of a feeder for abrasive grain is made of the same material
that runs through the feeder, allowing a continuous restoration of the
surface.
34.
Rejecting and regenerating parts
a. After it has completed its function or become useless, reject or modify (e.g.
discard, dissolve, evaporate) an element of an object.
b. Immediately restore any part of an object which is exhausted or depleted.
Examples:
35.
•
Bullet casings are ejected after the gun fires
•
Rocket boosters separate after serving their function
Transformation of the physical and chemical states of an object
Change an object's aggregate state, density distribution, degree of flexibility,
temperature.
128
Example:
•
In a system for brittle friable materials, the surface of the spiral feedscrew
was made from an elastic material with two spiral springs. To control the
process, the pitch of the screw could be changed remotely.
36.
Phase transformation
Implement an effect developed during the phase transition of a substance. For
instance, during the change of volume, liberation or absorption of heat.
Example:
•
To control the expansion of ribbed pipes, they are filled with water and
cooled to a freezing temperature.
37.
Thermal expansion
a. Use a material which expands or contracts with heat.
b. Use various materials with different coefficients of heat expansion.
Example:
•
To control the opening of roof windows in a greenhouse, bimetallic plates
are connected to the windows. A change in temperature bends the plates,
causing the window to open or close.
38.
Use strong oxidizers
a. Replace normal air with enriched air.
b. Replace enriched air with oxygen.
c. Treat an object in air or in oxygen with ionizing radiation.
d. Use ionized oxygen.
Example:
•
To obtain more heat from a torch, oxygen is fed to the torch instead of
atmospheric air.
39.
Inert environment
a. Replace the normal environment with an inert one.
129
b. Carry out the process in a vacuum.
Example:
•
To prevent cotton from catching fire in a warehouse, it is treated with inert
gas while being transported to the storage area.
40.
Composite materials
Replace a homogeneous material with a composite one.
Example:
•
Military aircraft wings are made of composites of plastics and carbon
fibers for high strength and low weight.
3
4
5
6
7
8
9
Part ID #
# of times the operation is
carried out consecutively
Two-digit manual handling
code
Manual handling time per part
Two-digit manual insertion
code
Manual insertion time per part
Estimation of theoretical
minimum # of parts, 0 or 1
2
Operation cost, cents, 0.4 (US)
x (7)
1
Operation time, sec, (2) x [(4) +
(7)]
0
Name of Part
130
Appendix 2C – DFA Worksheet
1
0
0
0
2
0
0
0
3
0
0
0
4
0
0
0
5
0
0
0
6
0
0
0
7
0
0
0
8
0
0
0
9
0
0
0
10
0
0
0
11
0
0
0
12
0
0
0
13
0
0
0
14
0
0
0
15
0
0
0
16
0
0
0
17
0
0
0
18
0
0
0
19
0
0
0
20
0
0
TM
CM
0
NM
0
0
0
131
APPENDIX 2D – TABLE OF MANUAL HANDLING ESTIMATED TIMES
132
APPENDIX 2E – TABLE OF MANUAL INSERTION ESTIMATED TIMES
133
APPENDIX 2F – TABLE OF COMPATIBILITY BETWEEN PROCESSES
AND MATERIALS
134
APPENDIX 2G – TABLE OF SHAPE GENERATION CAPABILITIES OF
PROCESSES
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Wiper Holder
Female Adjuster
Knob
Male Adjuster
Stopper
Rod A
Rod B
Snap Fit Shaft 1
Snap Fit Shaft 2
Snap Fit Shaft 3
Handle
Pusher
Joint
No
Yes
No
No
No
No
Yes
No
Yes
Yes
Yes
Yes
Yes
UniWall
Yes
B. Durability (Plastic part)
Material requirement : A. Excellent Corrosion (Metal part)
Depress
Yes
Name of component
Connector
No
Yes
No
No
No
No
No
No
Yes
Yes
Yes
No
No
UniSect
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
Yes
Yes
AxisRot
No
No
No
Yes
Yes
Yes
No
Yes
Yes
No
No
No
Yes
Yes
RegXSec
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
CaptCav
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Enclosed
No
APPENDIX 7A - PART ATTRIBUTES OF EACH PART FOR NEW DESIGN OF SPONGE MOP
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
No
No
No
NoDraft
No
135
136
APPENDIX 7B – TABLE OF PRIMARY PROCESS SELECTION FOR NEW
DESIGN
No.
Name of Component
Process
1
Connector
Injection Molding
2
Wiper Holder
Injection Molding
3
Female Adjuster
Injection Molding
4
Knob
Injection Molding
5
Male Adjuster
Injection Molding
6
Stopper
Injection Molding
7
Rod A
Hot Extrusion
8
Rod B
Hot Extrusion
9
Snap Fit Shaft 1
Powder Metal Part
10
Snap Fit Shaft 2
Powder Metal Part
11
Snap Fit Shaft 3
Powder Metal Part
12
Handle
Injection Molding
13
Pusher
Powder Metal Part
14
Joint
Injection Molding
137
APPENDIX 7B – TABLE OF MATERIAL SELECTION FOR NEW DESIGN
No.
Name of Component
Material
1
Connector
Polypropylene
2
Wiper Holder
Polypropylene
3
Female Adjuster
Polypropylene
4
Knob
Polypropylene
5
Male Adjuster
Polypropylene
6
Stopper
Polypropylene
7
Rod A
Aluminum
8
Rod B
Aluminum
9
Snap Fit Shaft 1
Stainless Steel
10
Snap Fit Shaft 2
Stainless Steel
11
Snap Fit Shaft 3
Stainless Steel
12
Handle
Polypropylene
13
Pusher
Stainless Steel
14
Joint
Stainless Steel
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Wiper Holder
Female Adjuster
Knob
Male Adjuster
Stopper
Rod A
Rod B
Snap Fit Shaft 2
Snap Fit Shaft 3
Handle
Pusher
Joint
Yes
Yes
No
No
No
Yes
No
Yes
Yes
Yes
Yes
Yes
UniWall
Yes
B. Durability (Plastic part)
Material requirement : A. Excellent Corrosion (Metal part)
Depress
Yes
Name of component
Connector
No
Yes
No
No
No
No
No
Yes
Yes
Yes
No
No
UniSect
No
No
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
No
Yes
Yes
AxisRot
No
No
No
Yes
Yes
No
Yes
Yes
No
No
No
Yes
Yes
RegXSec
No
No
No
No
No
No
No
No
No
No
No
No
Yes
CaptCav
No
No
No
No
No
No
No
No
No
No
No
No
No
Enclosed
No
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
No
No
No
NoDraft
No
APPENDIX 7C - PART ATTRIBUTES OF EACH PART FOR NEW DESIGN OF SPONGE MOP BY TRIZ CONCEPT.
138
139
APPENDIX 7D – TABLE OF PRIMARY PROCESS SELECTION FOR NEW
DESIGN BY TRIZ CONCEPT
No.
Name of Component
Process
1
Connector
Injection Molding
2
Wiper Holder
Injection Molding
3
Female Adjuster
Injection Molding
4
Knob
Injection Molding
5
Male Adjuster
Injection Molding
6
Stopper
Injection Molding
7
Rod A
Hot Extrusion
8
Rod B
Hot Extrusion
9
Snap Fit Shaft 2
Powder Metal Part
10
Snap Fit Shaft 3
Powder Metal Part
11
Handle
Injection Molding
12
Pusher
Powder Metal Part
13
Joint
Powder Metal Part
140
APPENDIX 7D – TABLE OF MATERIAL SELECTION FOR NEW DESIGN
BY TRIZ CONCEPT
No.
Name of Component
Material
1
Connector
Polypropylene
2
Wiper Holder
Polypropylene
3
Female Adjuster
Polypropylene
4
Knob
Polypropylene
5
Male Adjuster
Polypropylene
6
Stopper
Polypropylene
7
Rod A
Aluminum
8
Rod B
Aluminum
9
Snap Fit Shaft 2
Stainless Steel
10
Snap Fit Shaft 3
Stainless Steel
11
Handle
Polypropylene
12
Pusher
Stainless Steel
13
Joint
Stainless Steel