Design and Development of Grass Cutting Machine Using DFMA Methodology
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Transcript of Design and Development of Grass Cutting Machine Using DFMA Methodology
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UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Design and Development of Grass Cutting
Machine using DFMA Methodology
Thesis submitted in accordance with the requirements of Universiti Teknikal
Malaysia Melaka for the Bachelors degree in Manufacturing Engineering
(Manufacturing Design) with Honours
By
MOHD ISHAMMUDIN BIN MOHD YUNUS
Faculty of Manufacturing Engineering
April 2008
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UTeM Library (Pind.1/2007)
SULIT
TERHAD
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam
AKTA RAHSIA RASMI 1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi/badan di mana penyelidikan dijalankan)
(TANDATANGAN PENULIS)
Alamat Tetap: NO 453,Jln Hj Adnan, Kg Gching,
43900,Sepang, Selangor Darul Ehsan
Tarikh:
* Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM). ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.
BORANG PENGESAHAN STATUS TESIS*
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
JUDUL: _______________________________________________________________ _______________________________________________________________
SESI PENGAJIAN : _______________________
Saya _____________________________________________________________________
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:
1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran
antara institusi pengajian tinggi.
4. **Sila tandakan ()
Design and Development of Grass Cutting Machine using DFMA Methodology
2007/2008
MOHD ISHAMMUDIN BIN MOHD YUNUS
(TANDATANGAN PENYELIA)
Cop Rasmi:
Tarikh: _______________________
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DECLARATION
I hereby, declare this thesis entitled Design and Development of Grass Cutting Machine
using DFMA Methodology is the results of my own research
except as cited in the reference.
Signature : ...
Authors Name :
Date :
MOHD ISHAMMUDIN BIN MOHD YUNUS
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APPROVAL
This thesis submitted to the senate of UTeM and has been accepted as fulfillment of the
requirement for the degree of Bachelor of Engineering Manufacturing (Design). The
members of the supervisory committee are as follows:
Main supervisor
Faculty of Manufacturing Engineering
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ABSTRACT
This project describes about the implementation of redesign the grass cutting machine by
using the application of Design for Manufacturing and Assembly (DFMA) methodology.
The scope based on the existing grass cutting machine and the appropriate of DFMA
methodology. The method used for gaining the data is from the reassembled the existing
grass cutting machine. From the data achieved, it can be classified into several categories
to be studied. Data will be analyzed by using Lucas Hull method to verify the design
efficiency, handling ratio and fitting ratio to achieve. The tools that used is TeamSET
software. The new proposed design of grass cutting machine drawn using SolidWorks
software based on TeamSET result achieved. Result shown that the design efficiency for
redesign grass cutting machine obtained better percentage rather than the existing design.
From the study, the total part, handling ratio fitting ratio and cost of existing design is
reduced. Eventually, the improvement of redesign grass cutting machine finally will be
able to meet user requirements and satisfactions.
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ABSTRAK
Kertas kerja ini menghuraikan tentant perlaksanaan dalam mereka bentuk semula mesin
pemotong rumput dengan menggunakan aplikasi DFMA (Design for Manufacturing and
Assembly). Skop projek adalah memfokus kepada rekabentuk asal mesin pemotong
rumput dan disertakan dengan aplikasi DFMA. Kaedah yang digunakan untuk
mendapatkan data adalah daripada memasang semula mesin pemotong rumput. Hasil data
yang diperolehi akan dikelaskan kepada beberapa kategori sebelum analisa dilakukan.
Kemudian, kesemua data tersebut akan dianalisa dengan menggunakan kaedah Lucas
Hull untuk menentukan kecekapan rekabentuk, nisbah pengendalian, nisbah perhimpunan
sebagai pencapaian objektif projek. Perkakasan yang terlibat adalah perisian TeamSET.
Rekabentuk mesin pemotong rumput yang baru akan di lukis menggunakan perisian
SolidWorks berdasrkan keputusan yang dicapai daripada perisian TeamSET. Keputusan
menunjukkan bahawa kecekapan reka bentuk untuk rekabentuk semula mesin pemotong
rumput memperolehi peratusan lebih baik daripada rekabentuk yang asal. Daripada
kajian, bahagian terjumlah, nisbah pengendalian, nisbah perhimpunan dan kos telah
dikurangkan. Akhirnya, peningkatan rekabentuk semula mesin pemotong rumput
akhirnya akan dapat bertemu keperluan dan kepuasan pengguna.
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DEDICATION
For my beloved mother and father
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ACKNOWLEDGEMENTS
First and foremost, I would like to express my highest appreciation to my supportive
academic supervisor, Mr.Zolkarnain B. Marjom. His supervision and support that gave
me truly helps during the period of conducting my thesis. His never-ending supply of
valuable advice and guidance has enlightens me and deeply engraved in my mind.
Next, I would like to dedicate my thankfulness to the helpful of Mr. Saifudin, for his
enthusiastic support and supervision of the thesis revision. Im also happy to present my
gratefully acknowledge to Machinery laboratory technicians, who has been so warmth
and kind to provide sincere assistance and good cooperation during the training period.
Their co-operation is much indeed appreciated. In addition, I would like to convey thanks
to FKP lecturers, for their assistance, which really spends their time to teach me a lots of
knowledge regarding to the design development.
Last but not least, I would like to state my appreciation to the staff Faculty of
Manufacturing Engineering, FKP, my friend and colleagues for supporting me and
administration department for their help in the project . Thank you.
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TABLE OF CONTENTS
Abstract.i
Abstrak ii
Dedication...............iii
Acknowledgements.iv
Table of Contents.v
List of Figures.ix
List of Tables..............xi
List of Sign and Symbolxii
1. INTRODUCTION...........................................................1
1.1 General Introduction....................................................1
1.2 Problem statement2
1.3 Objective..3
1.4 Scope of study..3
2. LITERATURE REVIEW...4
2.1 Introduction..4
2.2 Design for Manufacturing and Assembly (DFMA).5
2.3 Boothroyd Dewhurst DFA method..7
2.4 The Lucas DFA method...8
2.4.1 Functional Analysis..10
2.4.2 Handing Analysis..............10
2.4.3 Fitting Analysis.............12
2.5 The Guidelines of DFA..............13
2.5.1 A DFA guideline...13
2.5.2 Design Guidelines for Part Handling................14
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2.5.3 Design Guidelines for Insertion and Fastening.14
2.6 Types of Assembly15
2.7 DFA Process..16
2.8 Design for Manufacture Guidelines...17
2.8.1 General Principles of manufacturability...17
2.9 TeamSET...19
2.10 Application of DFMA in industry...21
2.10.1 Application of DFMA in aerospace industry.21
2.10.2 Application of DFMA in automotive industry...24
2.10.3 Application of DFMA in medical instrument industry..26
3. METHODOLOGY27
3.1 Method of Study27
3.2 TeamSET process flow..29
3.3 TeamSET database process....30
3.4 DFA analysis for existing product.34
3.4.1 Flow chart of existing product...............34
3.4.2 Flow chart of base part...............34
3.4.3 Flow chart of upper tunnel part..35
3.4.4 Flow chart of lower tunnel part..36
3.4.5 Detail drawing of existing product37
3.4.6 TeamSET analysis for existing product.37
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4. RESULT AND ANALYSIS...39
4.1 Introduction of analysis..39
4.2 Draw design using SolidWork software40
4.2.1 Detail drawing of first redesign.40
4.2.2 Detail drawing of second redesign.41
4.3 Analysis using TeamSET software42
4.3.1 DFA analysis for first redesign..42
4.3.1.1 Flow chart of first redesign44
4.3.1.2 Flow chart of upper tunnel part after first redesign...44
4.3.1.3 Flow chart of lower tunnel part after first redesign...45
4.3.1.4 Flow chart of base part after first redesign46
4.3.1.5 TeamSET analysis for first redesign..47
4.3.2 DFA analysis for second redesign.............48
4.3.2.1 Flow chart of second redesign...49
4.3.2.2 Flow chart of base structure part...49
4.3.2.3 Flow chart of cylinder blade part...50
4.3.2.4 Flow chart of tunnel part50
4.3.2.5 Flow chart of pulley system part51
4.3.2.6 TeamSET analysis for second redesign.51
4.4 Material and process selection.53
4.4.1 Shaft blade and shaft connector.53
4.4.2 Cylinder blade54
4.4.3 Base structure.55
4.4.4 Tunnel56
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5. DISCUSSION.57
5.1 Comparison of existing design with first and second redesign..57
5.2 Safeguards for prevent from mechanical hazards..59
6. CONCLUSION & FUTURE WORKS ...61
6.1 Conclusion.61
6.2 Future works..62
REFERENCES63
APPENDIX
A Gantt chart for PSM 1 & 2
B Detail drawing for redesign Grass Cutting Machine
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LIST OF FIGURE
1.1 The grass cutting machine 2
2.1 Flow chart of Lucas Hull method 9
2.2 Show DFA analysis 20
2.3 Show view of Longbow Apache Helicopter 23
2.4 Explode view of existing design of overhead luggage rack 24
2.5 Explode view of new design of overhead luggage rack 25
2.6 BagEasy III 26
3.1 Flow chart of Planning of the Study 28
3.2 The process flow in developing TeamSET database 29
3.3 The product maintaining projects, products and design scenarios 30
3.4 Product Breakdown Structure 31
3.5 Assembly Window 32
3.6 DFA analysis for assembly parts 33
3.7 A flow chart of existing product main part 34
3.8 A flow chart of base part 35
3.9 A flow chart of upper tunnel part 36
3.10 A flow chart of lower tunnel part 36
3.11 View of the existing product 37
3.12 TeamSET analysis for existing product 38
4.1 View of first redesign 40
4.2 View of second redesign 41
4.3 A flow chart of first redesign main part 44
4.4 A flow chart of upper tunnel part after redesign 45
4.5 A flow chart of lower tunnel part after redesign 45
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4.6 A flow chart of base part 46
4.7 TeamSET analysis for improvement design 47
4.8 A flow chart of final design main part 49
4.9 A flow chart of base structure part 49
4.10 A flow chart of cylinder blade part 50
4.11 A flow chart of V-belt part 51
4.12 TeamSET analysis for second redesign 52
4.13 Drawing of shaft blade and shaft connector 53
4.14 View of cylinder blade 54
4.15 View of base structure 55
4.16 Cross section view of tunnel 56
4.17 Isometric view of tunnel 56
5.1 Part for accessories 59
5.2 View of the second redesign after installation accessories 60
6.1 Shows the comparison between existing product and second
redesign
61
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LIST OF TABLE
2.1 Lucas DFA method - Manual Handling Analysis 11
2.2 Lucas DFA method - Manual Fitting Analysis 12
2.3 Pilot's Instrument Panel Estimate Summary 23
4.1 Quantity List of a first redesign 43
4.2 Quantity List of a second redesign 48
5.1 Comparison of existing design with fisrt redesign 58
5.2 Comparison of existing design with second redesign 58
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LIST OF SIGN & SYMBOL
DFMA - Design for Manufacturing and Assembly
DFA - Design for Assembly
DFM - Design of Manufacturing
PDS - Product Design Specification
QFD - Quality Function Deployment
MA - Manufacturing Analysis
FMEA - Failure Modes and Effects Analysis
DTC - Design to Target Cost
ASF - Assembly Flowchart
IPD - Integrated Product Development
PEP - Engineering and Planning
IEFAB - Improved Extended Avionics Bay
CAD - Computer Aided Design
PBS - Product Breakdown Structure
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CHAPTER 1
INTRODUCTION
1.1 General Introduction
Product lifecycle is being reduced drastically due to rapid changes in technology and
customers requirements. The global marketplace is changing so rapidly that industrialist
needs to adopt new strategies to respond customers requirement and in order to satisfy
the market needs more efficiently and quickly. Many companies especially in Japan,
USA and Europe have already started to implement techniques and tools that would
enable them to respond more quickly to consumers demand in delivering high quality
product at reasonable costs. The delay in time-to-market can be interpreted as a loss in
profit (Alan F & Jan Chal, 1994).
Currently, the implementation of Design for Manufacturing and Assembly (DFMA)
methodology are applied either manually or computer-aided. Most of the applied
interested in implementing DFMA are hindered by lack of clear guidelines or procedures
and no integration of isolated design and manufacturing teams. The advantages of the
integration are to decrease the number of part design and indirectly to reduce cost and
time. At the same time, it fulfills customers requirement. In this project, DFMA has been
applied in design and development the grass cutting machine. The design also must be
concerned to the requirement of the DFMA methodology in order to achieve high rank of
market selling.
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1.2 Problem statement
In developing this project, there are several problems that need to be concerned and the
most suitable method that can be used to solve the problems is by applying the Design for
Manufacturing and Assembly (DFMA) methodology. In identifying of grass cutting
machine problems, the most important aspects that need to be concerned is the design of
the grass cutting machine. Some of the part grass cutting machine are being designed
quite complicated with accessories and need to be eliminated, in the same time reduced
the manufacturing cost and assembly time. Besides that, there are several parts had been
recognized that difficult to handle. So, with the application of Design for Manufacturing
and Assembly (DFMA) methodology is highly expected in solving these problems to suit
the customer requirements and convenient.
Figure 1.1: The grass cutting machine
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1.3 Objective
The main objective of this project is using DFMA methodology to design the new grass
cutting machine and compare with the existing product. Beside that, other specific
objectives include:
a) to develop the grass cutting machine;
b) to design and analysis of original design;
c) to purpose grass cutting machine using DFMA method and TeamSET
software;
d) to determine the optimum manufacturing and assembly method for low
cost production with short production time.
1.4 Scope of study
a) Case study
A grass cutting machine has been selected as a case study for this project and had the
potential to be redesign by applying the Design for Manufacturing and Assembly
(DFMA) methodology. The tool selected for drawing the grass cutting machine is
SolidWork. User can easily generate drawing from a model. Photorealistic rendering
and animation that allow communicating how future products will look and perform
early in the development cycle.
b) Design for Assembly (DFA)
DFA is a systematic methodology that reduces manufacturing costs, total number of
parts in a product, and etcetera. For this project, the software called TeamSET is used
to analyze the design for existing product and redesign product.
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CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
To develop this project, the case study is to apply the Design for Manufacturing and
Assembly (DFMA). There are certain important DFMA tools that have been applied such
as Design for Assembly (DFA) and Design for Manufacture (DFM). These two important
DFMA tools are very useful especially to the industry. This chapter described about the
definition of Design for Manufacturing and Assembly (DFMA), Boothroyd Dewhurst
DFA method, the Lucas DFA method, the application of DFMA in industry and
application of engineering software called TeamSET.
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2.2 Design for Manufacturing and Assembly (DFMA)
Design for Manufacturing and Assembly (DFMA) is a design philosophy used by
designers when a reduction in part counts, a reduction in assembly time, or a
simplification of subassemblies is desired. It can be used in any environment regardless
of how complex the part is or how technologically advanced this environment may be.
DFMA encourages concurrent engineering during product design so that the product
qualities reside with both designers and the other members of the developing team (D-
ESPAT, 2007).
According to Geoffrey Boothroyd, Professor of Industrial and Manufacturing at the
University of Rhode Island, the practices now known as Design for Assembly (DFA),
and Design for Manufacture (DFM) had their start in the late 1970's at the University of
Massachusetts. Of all the issues to consider, industry was most interested in Design for
Assembly. When developing a product, the maximum potential cannot be achieved
without considering all phases of the design and manufacturing cycle. DFMA meets this
demand by addressing key assembly factors before the product goes on to the prototype
stage. These key factors are the product appearance, type, the number of parts required in
the product, and the required assembly motions and processes (D-ESPAT, 2007).
The Term DFMA comes with the combination of DFA (Design for Assembly) and
DFM (Design of Manufacturing). The basic concept of it is that the design engineers
apply the DFMA paradigm or software to analyze the manufacturing and assembly
problems at the early design stage. By this means, all of considerations about the factors
that affect the final outputs occur as early as possible in the design cycle. The extra time
spent in the early design stage is much less the time that will be spent in the repeatedly
redesign. And meanwhile, the cost will be reduced. DFM is that by considering the
limitations related to the manufacturing at the early stage of the design; the design
engineer can make selection among the deferent materials, different technologies,
estimate the manufacturing time the product cost quantitatively and rapidly among the
different schemes. They compare all kinds of the design plans and technology plans, and
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then the design team will make revises as soon as possible at the early stage of the design
period according this feedback information and determine the most satisfied design and
technology plan.
The three goals in DFM are:
1. Increase the quality of new produces during the development period, including
design, technology, manufacturing, service and so on.
2. Decrease the cost, including the cost of design, technology, manufacturing, delivery,
technical support, and discarding.
3. Shorten the developing cycle time, including the time of design, manufacturing
preparing, and repeatedly calculation.
DFA is considering and resolving the possible problems in the assembly process at the
early stage of the design which can make sure the part will be assembled with high speed,
low cost and productivity. DFA is a kind of design paradigm with which, the engineer
use all kinds of methods such as analyze, estimating, planning and simulating to consider
all the factors that will affect the assembly process during the whole design process;
revise the assembly constructions to satisfied the characteristics and functions of the final
products; and meanwhile, lower the cost as most as possible.
DFA is a kind of design method that can be used in two ways. The ways is a tool for
assembly analysis and a guide for assembly design. The former usage is that at the time
after the beginning of the product design, the engineer makes estimation of assembly
possibility by analyzing all the factors that can affect the assembly process, and give
suggestions. The second one is that collecting the knowledge and experience from the
assembly experts and recording them as design guides. By the help of these guides, the
engineer can choose the design plan and determine the product construction such as
under the guidance of those experts.
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2.3 Boothroyd Dewhurst DFA method
In the history of DFMA, Ford and Chrysler use the DFM philosophy in their design and
manufacturing process of the weapons, tanks and other military products. Dr. Geoffrey
Boothroyd and Dr. Peter Dewhurst who founded the Boothroyd Dewhurst, Inc (BDI) in
1982 are the first persons doing the research job in this new technology at the beginning
in the early 1970s. Actually, the DFMA is a trademark of their company. They created
and developed the DFMA concept which is used in developing the products of their
company --- DFMA software system. Currently these programs are used to help the
design in almost all the industrial fields including circuit boards (G. Boothroyd & W.
Knight, 1993), with manual assembly, with robotic assembly, and with machining. They
also do a lot of work examining the economic justification of each design revision (G.
Causey, 1999).
They created and developed the DFMA concept which is used in developing the products
of their company such as DFMA software system. Currently these programs are used to
help the design in almost all the industrial fields including circuit boards, with manual
assembly, with robotic assembly, and with machining. They also do a lot of work
examining the economic justification of each design revision.
In generally, Boothroyd Dewhurst DFA method can determine the appropriate assembly
method and reducing the number of individual parts to be assembled. This method also
can ensure that the remaining parts are easy to assemble. The methods of assembly are
classified into three basic categories such as manual assembly, special-purpose transfer
machine assembly and robot assembly.
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2.4 The Lucas DFA method
Although the Boothroyd-Dewhurst method is widely used, it is based on timing each of
the handling and insertion motions. Although tables of data are available, the most
accurate numbers are compiled through time studies in particular factories.
The basic construction of Lucas DFA is very similar to the DFA of BDI, it is the result of
the cooperation of Lucas Organization and the University of Hull in U.K. Now, the logic
of Lucas DFA has been integrated in the engineering analysis software TeamSet which
is the product of CCI Lucas DFA separates the product design process into three stages:
FcA (Function Analysis), HA (Handing Analysis) and FtA (Fitting Analysis). The
relations of these three stages are shown in Figure 2.1. Before the manufacturing and
assembly process, the PDS (Product Design Specification) occurs which change the
requirements of the customs into engineering specifications. After that, the design
engineers perform the design job according to this information. This is a kind of process
to change the engineering specifications into the real design and meanwhile, all the
requirements should be satisfied.
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Figure 2.1: Lucas Hull method
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2.4.1 Functional Analysis
In this analysis, the components of the product are reviewed only for their function. The
components are divided into two groups. Parts that belong to Group A are those that are
deemed to be essential to the product's function; Group B parts are those that are not
essential to the product's function. Group B functions include fastening, locating, and
etcetera. The functional efficiency of the design can be calculated as (Vincent Chan &
Filippo A. Salustri, 2005):
Ed = A/(A+B) x 100%
Where A is the number of essential components, and B is the number of non-essential
components. The design efficiency is used to pre-screen a design alternative before more
time is spent on it. This is different than the Boothroyd-Dewhurst method (which
assumes a design is already available). This analysis is intended to reduce the part count
in the product. Typically, a design efficiency of 60% is targeted for initial designs.
2.4.2 Handing Analysis
Similar to the Boothroyd-Dewhurst analysis, both the part handling and insertion times
are examined here. In the feeding analysis, the problems associated with the handling of
the part are scored using an appropriate table. For each part, the individual feeding index
is scored. Generally, the target index for a part is 1.5. If the index is greater than 1.5, the
part should be considered for redesign. Overall, all of the product's components should
meet a "feeding ratio" defined as (Vincent Chan & Filippo A. Salustri, 2005):
Handling Ratio = (Total Feeding Index) / (Number of Essential Components)
Total Handling Index = A+B+C+D
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Where the total feeding index is the sum of all the indices of all the parts. The number of
essential components is the value A from the functional analysis. An ideal feeding ratio is
generally taken to be 2.5
Table 2.1: Lucas DFA method - Manual Handling Analysis
A. Size & Weight of Part One of the following
Very small - requires tools 1.5
Convenient - hands only 1
Large and/or heavy
requires more than 1 hand 1.5
Large and/or heavy
requires hoist or 2 people 3
B. Handling difficulties
All that apply
Delicate 0.4
Flexible 0.6
Sticky 0.5
Tangible 0.8
Severely nest 0.7
Sharp/Abrasive 0.3
Untouchable 0.5
Gripping problem / slippery 0.2
No handling difficulties 0
C. Orientation of Part
One of the following
Symmetrical, no orientation
required 0
End to end, easy to see 0.1
End to end, not visible 0.5
D. Rotational Orientation of Part
One of the following
Rotational Symmetry 0
Rotational Orientation, easy to see 0.2
Rotational Orientation, hard to see 0.4
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2.4.3 Fitting Analysis
The fitting analysis is calculated similarly to the feeding analysis. Again, a fitting index
of 1.5 is a goal value for each assembly. However, it should be noted that there is usually
greater variance in the fitting indices than in the feeding indices. Again, an overall fitting
ration of 2.5 is desired (Vincent Chan & Filippo A. Salustri, 2005).
Fitting Ratio = (Total Fitting Index) / (Number of Essential Components)
Total Fitting Index = A+B+C+D+E+F
Table 2.2: Lucas DFA method - Manual Fitting Analysis
A. Part Placing and Fastening
One of the following
Self-holding orientation 1.0
Requires holding
Plus 1 of the following 2.0
Self-securing (i.e. snaps) 1.3
Screwing 4.0
Riveting 4.0
Bending 4.0
B. Process Direction
One of the following
Straight line from above 0
Straight line not from above 0.1
Not a straight line 1.6
C. Insertion
One of the following
Single 0
Multiple insertions 0.7
Simultaneous multiple insertions 1.2
E. Alignment
One of the following
Easy to align 0
Difficult to align 0.7
F. Insertion Force
One of the following
No resistance to insertion 0
Resistance to insertion 0.6
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2.5 The Guidelines of DFA
The general guidelines of DFA that attempt to consolidate manufacturing knowledge and
present them to the designer in the form of simple rules to be followed when creating a
design. The process of assembly can be divided naturally into two separate areas,
handling assembly which means acquiring, orienting and moving the part. The secondly
area is insertion and fastening assembly which means mating a part to another part group
or group of part.
2.5.1 A DFA guideline
A DFA guideline is given below:
a) Aim for simplicity
Minimize part numbers, part variety, assembly surfaces; simplify assembly
sequences, component handling and insertion, for faster and more reliable assembly.
b) Standardize
Standardize on material usage, components, and aim for as much off-the-shelf
component as possible to allow improved inventory management, reduced tooling,
and the benefits of mass production even at low volumes.
c) Rationalize product design
Standardize on materials, components, and subassemblies throughout product
families to increase economies of scale and reduce equipment and tooling costs.
Employ modularity to allow variety to be introduced late in the assembly sequence
and simplify JIT production.
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2.5.2 Design Guidelines for Part Handling
a) Design parts that have end-to-end symmetry and rotational symmetry about the
axis of insertion. If not try to design parts having the maximum possible
symmetry.
b) Design parts that, in those instances where the part cannot be made symmetric,
are obviously asymmetric
c) provide features that will prevent jamming of parts that tend to nest or stack when
stored in bulk
d) avoid features that will allow tangling of parts when stored in bulk
e) Avoid parts that stick together or are slippery, delicate, flexible, very small or
very large or that are hazardous to the handler.
2.5.3 Design Guidelines for Insertion and Fastening
a) Design with little or no resistance to insertion and provide chamfers to guide
insertion of two mating parts to provide generous clearance but not resulted for
parts to jam or hang-up during insertion
b) Standardize by using common parts, processes and methods across all models and
product lines to permit the use of higher volume processes that normally result in
lower product cost
c) Use pyramid assembly to provide for progressive assembly about one axis of
reference and it is best to assemble from above.
d) Try to avoid the necessity for holding parts down to maintain their orientation
during manipulation of the subassembly or during the placement of another part.
e) Design so that a part is located before it is released.
f) Try to follow the sequence of the mechanical fasteners and listed in order of
increasing manual assembly cost.
g) Avoid the need to reposition the partially completed assembly in the fixture.
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2.6 Types of Assembly
There are three types of assembly, classified by the level of automation.
a) Manual assembly a human operator at a workstation reaches and grasps a part
from a tray, and then moves, orients and prepositions the part for insertion. The
operator then places the parts together and fastens them, often with a power tool.
The design Guidelines for Manual Assembly are:
i. Minimize the number of different parts use standard parts.
ii. Minimize the number of parts.
iii. Avoid or minimize part orientation during assembly
iv. Prefer easily handled parts that do not tangle or nest within one another.
b) Automatic assembly handling is accomplished with a parts feeder, like a
vibratory bowl, which in turn inserts the part. The design guidelines for
Automatic Assembly:
i. Reduce the number of different component by considering
ii. Use self-aligning and self-locating features
iii. Avoid screws/bolts.
c) Robotic assembly the handling and insertion of the part is done by a robot arm
under computer control. The cost of assembly is determined by the number of
parts in the assembly and the ease with which the parts can be handled and
inserted. Design can be have strong influence in both areas. Reduction in the
number of parts can be achieved by eliminating of parts example replacing screws
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16
and washers with snap or press fit and by combining several parts into a single
component. Ease of handling and insertion is achieved by designing so that the
parts cannot become tangled or nested in each other and by designing with
symmetry in mind. Parts that do not require end-to-end orientation prior to
insertion as a screw does should be used if possible. Parts with complete
rotational symmetry around the axis of insertion like a washer are best.
2.7 DFA Process
Once parts are manufactured, they need to be assembled into subassemblies and products.
The assembly process consists of two operations, handling followed by insertion. The
DFA is a two step process (Shih-Wen Hsiao, 2001): -
a) Evaluate the assemblability of the individual parts whether they are easy to be
assembled or not.
b) Evaluate the theoretical minimum number pf parts that should be in the product.
In step 1 the designer uses some established rating system to evaluate each individual part
with respect to its:
Graspability: To check that the part is easy to be grasped or not during the period of
assembly.
Orientability: To check if the part is easy to be oriented or not when it is being
assembled
Transferability: To check whether the part is easy to be transferred to the work position
or not.
Insertability: To check if the part is easy to be inserted into the correct position or not
when it is being assembled.
Secureability: To check whether the part or the product is secure or not after the part has
been assembled.
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17
2.8 Design for Manufacture Guidelines
Design for manufacture or 'Manufacturability' concerns the cost and difficulty of making
the product. At a simple level manufacturability, design for manufacture (DFM) at a part
level, involves detail such as ensuring that where a pin is to be assembled into a hole that
is only slightly larger in diameter, then it is much easier if the end of the pin or the entry
to the hole (or both) are chamfered or finished with a radius. This applies whether the
assembly is carried out manually or automatically. This is a fine tuning process carried
out once the product form has been decided. Indeed automatic assembly would be very
difficult / expensive if neither component of a close fitting pair was chamfered. At a more
complex level, product DFM tackles the more fundamental problem of deciding on the
product structure and form. Design for assembly (DFA) is an important part of this.
Some 'manufacturability' software is available, relating both to manufacture and to
assembly. This section starts with some simple but important principles of
manufacturability (David Grieve, 2003).
2.8.1 General Principles of manufacturability
a) Reducing the number of parts frequently reduces the weight of the product which
is advantageous. Eliminating the need for a separate housing or enclosure can be
beneficial. One method that has been successful in many cases is to replace a
fabricated sub - assembly, which may utilize many fasteners, with a single
casting. In some cases this has given weight savings as well as cost savings.
b) A robust design is one that has been optimised so that variations from the nominal
specification cause a minimum loss of quality. To determine these optimal values
will normally necessitate experimental work on a prototype.
c) The assembly of products made up from 4 to 8 modules with 4 to 12 parts per
module can usually be automated most readily. It is also helpful to maintain a
generic configuration as far as possible into the assembly process and install
specialist modules as late as possible.
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18
d) Assembly from 1 direction is beneficial whether manual or automated assembly is
to be used. Generally assembling top down, along the z axis, like making a
sandwich, is the best solution.
e) Designing so only correct assembly is possible is useful where semi - skilled
labour is used and it is also desirable if there are safety considerations if the
product were to be incorrectly assembled. Manufacturers of mains powered
consumer electrical appliances frequently supply them with a flex having a
moulded on supply plug. This minimises the danger of the consumer incorrectly
wiring a plug and suffering an electric shock.
f) Using standard sizes will reduce costs directly and reduced delivery times will
indirectly give savings. This will also reduce the cost of repairs and maintenance.
g) Fasteners can add significantly to costs, frequently the cost of installation will
greatly exceed purchase cost. If fasteners must be used then minimise the sizes
and types. Small fasteners and parts should be avoided.
h) Mechanical adjustments add to the cost of fabrication and cause assembly, test
and reliability problems. The need for adjustments can often be negated by using
dowel pins, detents, notches or spring mounted components. If a designer
understands why an adjustment has been recommended, a way of eliminating or
reducing the need can often be found.
i) Wiring and other flexible components are difficult to handle during assembly.
The use of rigid or process applied gaskets, circuit boards rather than electric
wiring helps to minimize this problem.
j) Dimensioning from 1 datum simplifies gauging and minimizes errors in
tolerances. Dimensions should also be measured from points or surfaces on a
component, not points in space.
k) Using large radii is generally good practice for most processes, casting, forming
etc. as material flow is facilitated - and stress concentration is reduced. However
sharp corners are inevitable with some processes, eg 2 intersecting machined
surfaces and punch face - wall edge in a powdered metal component. There is no
cost advantage in preventing these sharp corners.
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19
l) In simultaneous or concurrent engineering, personnel from functions other than
design are involved in the design process, including manufacturing specialists.
This enables all aspects of a design to be considered at an early stage.
m) This can be critical, particularly for closer tolerance parts because as tolerances
become tighter, the rise in manufacturing costs is increasingly steep.
2.9 TeamSET
TeamSET is a PC based software package which helps designers produce better products
at reduced cost and in shorter times. TeamSET is a PC based software package based
integrated set of applications that support design team working and encourages a
multidisciplinary culture. The TeamSET concurrent engineering software toolkit
includes Quality Function Deployment (QFD) to help to understand the customers
wants, and develop the product specification, Design for Assembly (DFA) to simplify
product structure and optimise component handling and assembly, Manufacturing
Analysis (MA) to select the most appropriate materials and processes for component
manufacture, Failure Modes and Effects Analysis (FMEA) to ensure the design is robust,
Design to Target Cost (DTC) to monitor product costs throughout the design process, and
Controlled Concept Convergence to select the best options. The result from the tool kit
will helps product design teams to produce better products at lower cost and in a shorter
time (TeamSet, 2008). DFA analysis is carried out on a graphical chart as shown in
Figure 2.2
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20
The benefits of TeamSET are:
a) The provision of such a focus allows design team to explore and compare design or
re-design options quickly and with minimum effort.
b) Will allow user addressed such problems as time to market, quality, reliability and
cost by ensuring that the design to which user are committing is simple to
manufacture and assemble has a minimum of non-essential parts, keeps tooling costs
down and will meet customer needs.
c) Work from previous products, assemblies and part analysis can be re-used in later
design activities negating the need to start from scratch each time.
d) This will not only shorten analysis times but also enable user to capitalize on the
benefits that accrue from standardization, consistency and predictability.
Figure 2.2: DFA analysis
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21
Teamset is a result of the collaboration between lucas and the university of Hull. It does
not use cost analysis, and in this respect differs from the Hitachi and Boothroyd-
Dewhurst method. The method involves the assigning and summing of penalty factors
associated wih potential design problems, similar to the Hotachi method but with the
inclusion of handling as well as insertion. These are denoed in visual flow called an
Assembly Flowchart (ASF). The TeamSet database contains a number of projects, each
of whichwill contain a number of associated products. Each of these will have a number
of different design scenarios, which in turn well be broken down in a hierarchy of
elements a product breakdown structure. Each elements of this structure can be
associated with a particular assembly of parts for which detailed information is stored
(Anonymous, 1998).
2.10 Application of DFMA in industry
2.10.1 Application of DFMA in aerospace industry
This study examines the effectiveness of Design for Manufacturing and Assembly
(DFMA) methodology used by the design, manufacturing, quality, and supporting
engineers for the development of the Longbow Apache Helicopter. Data were obtained
through the Integrated Product Development (IPD) team for several redesigned areas of
the Longbow prototype Helicopter Crew Station. Results of the study show that DFMA
can be an effective approach, as indicated by a significant cost and weight savings (D-
ESPAT, 2007).
During the years of 1994 and 1995, MDHS redesigned and optimized one of the six
Longbow prototype helicopters. An Integrated Product Development (IPD) team was
formed to conduct this redesign. The IPD team is a concurrent engineering team where
representatives of several organizations such as engineering, manufacturing,
procurement, suppliers, product support, quality, and others, work together to develop a
product design. This design is then brought into production in a short period of time
without the budget and lengthy schedule usually encountered by other organizations
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22
without a team concept in place. Six helicopters were completed in the prototype phase
and the experience obtained from this phase was applied to the Longbow Initiatives
Project. During this project, Design and Producibility Engineering and Planning (PEP),
which was developed and implemented with the purpose of improving the previous
prototype aircraft configuration used DFMA as an aid to accomplish that established
objective. DFMA was applied to a limited number of parts within the crew station, and
the Improved Extended Avionics Bay (IEFAB) of the Longbow Apache Helicopter. Data
were gathered and recorded by the IPD Team and compared to the baseline prototype
helicopters which were designed without using DFMA (D-ESPAT, 2007).
Each DFMA case study was conducted by redesigning existing assemblies. The IPD team
met and analyzed its requirements, including material, function, and location of parts.
Once a preliminary design was done, the team studied it in order to reduce the part count,
weight, and assembly time. Data was obtained from each IPD team member that was
involved in the DFMA process. Their estimates, tables and schedules were analyzed. All
data that could be found relating to DFMA applications on the Longbow Apache
Program including: producibility analyses, design concept descriptions and lists, weight
data analysis, schedules based on the design and manufacturing plans, cost estimates, and
detailed DFMA plans on at least four assemblies, were used to assess the impact of
DFMA. Data were collected and summarized as they were made available by the IPD
Team (D-ESPAT, 2007).
Collected data were loaded into the Boothroyd Dewhurst Inc.'s (BDI) DFA 7.1a software.
This software analyzes the design, manufacturing, assembly process, and materials used.
It then summarizes and provides recommendations on how to improve the design using
DFMA philosophy (D-ESPAT, 2007).
The first assembly examined is the Pilot's Instrument Panel which is comprised of a
combination of sheet metal angles and extruded stiffeners. The panel itself is attached to
an existing airframe structure with rivets. It consists of 74 parts with a weight of 3.00
Kilograms. The fabrication time for this instrument panel is 305 hours. This panel also
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23
requires a final assembly tooling fixture in addition to tooling needed to form all brackets
and angles. Utilizing DFMA in conjunction with the IPD Team concept and availability
of HSDM, resulted in the redesign of the pilot's instrument panel, into only 9 parts (D-
ESPAT, 2007).
Subsequent analysis yielded data indicating that the fabrication time could be reduced to
20 hours. The total manufacturing and assembly time would be reduced from 697 hours
to 181 hours, weight reduction would be to 2.74 Kilograms, and the total cost was
reduced by 74%. The pilot's instrument panel DFMA concept is shown, and Table 1
provides a summary of the estimated comparison for the Pilot's Instrument Panel (D-
ESPAT, 2007).
Table 2.3: Pilot's Instrument Panel Estimate Summary
Figure 2.3: Show view of Longbow Apache Helicopter
Presenet Instument
Panels
DFMA Proposed
Instrument Panels
Part Count 74 pieces 9 pieces
Fabrication Time 305 Hours 20 Hours
Assembly/Installation
Time 149/153 Hour 8/153 Hour
Total Time 697 Hours 181 Hours
Weight 3.00 Kilograms 2.78 Kilograms
Cost 74% Reduction
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24
2.10.2 Application of DFMA in automotive industry
This study examines the effectiveness of Design for Manufacturing and Assembly
(DFMA) methodology used by the design, manufacturing, quality, and supporting
engineers for the development of the overhead luggage rack. The objective of this study
examines are reduce product cost, reduce assembly problems and improve function. The
existing design consisted of cast ribs, sheet material and numerous fasteners. At 43ft long
it is installed through the windscreen and then held in position while fasteners are
inserted horizontally and vertically to secure it. Subsequent replacement of the centre
roof trim was not possible (TeamSet, 2008b). Figure 2.4 show the explode view of
existing design.
Figure 2.4: Explode view of existing design of overhead luggage rack
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25
The new design uses 3 full length interlocking extrusions and a minimum of fasteners.
During installation the lower edge is hooked onto the body side supporting the main
weight of the assembly, it is then rotated upward into position and secured to the roof.
The centre roof trim can now be removed without disturbing the rack. A wiring harness
previously held by p clips and prone to damage by screws and screw drivers, is now
safely routed through a channel in one of the extrusions and retained by foam rubber
blocks (TeamSet, 2008b). The result achieve from this study examines is part reduction
from 4730 to 2210 and improvement installation time is 62 hours down to 17 hours.
Figure 2.5 show the explode view of new design.
Figure 2.5: Explode view of new design of overhead luggage rack
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26
2.10.3 Application of DFMA in medical instrument industry
The BagEasy III is a manual resuscitator designed for single patient use (to be used
multiple times on a single patient) by medical personnel in emergency rooms,
ambulances and other treatment locations. A design team was founded and the goal of the
team was to finish the design with a concept what would meet the product requirement
and meanwhile, improve the manufacturability of the product. They used Boothroyd-
Dewhurst DFMA as the framework during the whole design process. Throughout the
whole design process, every member of the team shared the ideals with each other. They
communicated every day and the team meeting happened anytime as needed. This
resulted breaking down the walls between functions and achieving parallel design
method which focused the team on the object. Every member knew their product and
what the product was going to be. Supplier took part in the team activities and answered
the questions from the designer on how the parts could be produced. The feedback comes
so quickly instead of long time waiting as usual. After the concept design finished,
models generated in CAD was used for analysis. As details of the design created, the
concept was turned into real-word models. The team members met the supplier at this
time, reviewed the part design and developed a better one. The results of these efforts are
that the new product is greatly simplified; the improvement of assembly is 84%, of
assembly cost is 74% (Xiaofan Xie, 2003). Figure 2.6 show the picture of BagEasy III.
Figure 2.6: BagEasy III
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27
CHAPTER 3
METHODOLOGY
3.1 Method of Study
In this section, the explanations is more on the project development which is based on the
chart to ensure the procedure and the steps of the project will be done properly in the
appropriate time which had been planed before. The methodology of the project starts
with the introduction of product to be studied and then some literature review on the
design for manufacturing and assembly method, application of DFMA and techniques for
case study. The data for literature review was founded from journals, related reference
books from library, and also internet. After that, the procedure goes on gaining the
information from the existing product. The method used for collecting data was from the
reassemble the existing product. These data were used to apply analysis using TeamSET
software. DFA analysis will be applied to the existing product design. The purpose of this
analysis is to verify the design efficiency of existing product including assembly process,
parts included and etcetera. Then from the result achieved, the result will be analyzed in
order to get the best design for redesign purposed. Solidwork software will be used in
order to make a drawing of redesign the existing product. Figure 3.1 shows the flow chart
of the planning of the study.
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28
Figure 3.1: Flow chart of Planning of the Study
Do Literatures
Understanding the Title, Problem Statement & Objectives
Start
Journal/
Reports
Existing Product
Analysis
Existing Product Specification
Discussion
Satisfy?
NO
YES
Existing
Product
Observation
Problems
Redesign Process
Technical Redesign Analysis
Transfer the Redesign into SolidWork
Conclusion & Future Work
Final Report
End
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29
3.2 TeamSET process flow
The TeamSET database contains a number of projects, each of which will contain a
number of associated products. Each of these will have a number of different design
scenarios, which in turn will be broken down in a hierarchy of elements which is a
product breakdown structure. Each element of this structure can be associated with a
particular assembly of parts for which detailed information is stored. Figure 3.2 showed
the process flow to develop the TeamSET database.
Figure 3.2: The process flow in developing TeamSET database
Projects
Products
Scenarios
Product breakdown
structure
Assemblies
Database
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30
3.3 TeamSET database process
a) Step 1
The first process is creating and maintaining projects, products and design scenarios
for product to be analyzed as show in Figure 3.3.
Figure 3.3: The product maintaining projects, products and design scenarios.
A product represents the
final deliverable item
A project allows to group
together products that
might be part of an overall
product line.
A scenario represents
alternative way of
manufacturing product and is
related to one PBS. As
comparison for electing best
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31
b) Step 2
Creating the Product Breakdown Structure (PBS) for products as shown in figure 3.4.
The PBS allows to:
i. Specify the number of times (quantity) that a particular element occur.
ii. Associate each element with an assembly.
Figure 3.4: Product Breakdown Structure
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32
c) Step 3
An assembly may be formed exclusively from a collection of simple parts or many
contain more complex parts as shown in Figure 3.5.
Figure 3.5: Assembly Window
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33
d) Step 4
Create a main work window to perform a DFA analysis on assembly parts as shown
in Figure 3.6.
Figure 3.6: DFA analysis for assembly parts.
Part list
HA to determine the difficulty of
handling and orientation
Assembly
flowchart
the final
deliverable
item
FA analysis to determine
whether A part or B part
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34
3.4 DFA analysis for existing product
3.4.1 Flow chart of existing product
Existing product can be divided to three main parts as follow: -
a) base part
b) Upper tunnel part
c) Lower tunnel part
Figure 3.7: A flow chart of existing product main part
3.4.2 Flow chart of base part
Base part had eleven sub-parts as follow: -
a) nut D12mm
b) bolt 17x76
c) washer D22mm
d) bearing
e) bearing holder
f) v-belt
g) pulley
h) motor
i) plug
j) cable
k) screw
Existing product
Upper tunnel
part
Base part Lower tunnel
part
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35
Figure 3.8: A flow chart of base part
3.4.3 Flow chart of upper tunnel part
Upper tunnel part had twelve sub-parts as follow: -
a) Nut D12mm
b) Nut D10mm
c) Bolt 17x36
d) Bolt 17x76
e) Washer D22mm
f) Washer D13mm
g) Safety guide
h) Rod
i) Blade
j) Allenkey screw
k) Bearing
l) Bearing holder
Nut
Base part
Bolt
Washer
Cable
Screw
Bearing
holder
Motor
V-belt
Bearing
Pulley
Plug
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36
Figure 3.9: A flow chart of upper tunnel part
3.4.4 Flow chart of lower tunnel part
Lower tunnel part had three sub-parts as follow: -
a) nut D 12mm
b) bolt 17x36
c) washer D22mm
Figure 3.10: A flow chart of lower tunnel part
Nut
D10m
m
Upper tunnel
part
Bolt17x3
6
Washer
D22mm
Blade Allenkey
screw
Bearing
holder
Rod Safety
guide
Bearing
Bolt17x76
Nut
D12mm
Lower tunnel part
Nut D12mm Washer
D22mm Bolt 17x36
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37
3.5 Detail drawing of existing product
TOP VIEW SIDE VIEW
FRONT VIEW ISOMETRIC VIEW
Figure 3.11: View of the existing product
3.6 TeamSET analysis for existing product
Figure 3.12 shows the analysis of existing product using TeamSET software. The result
shows about 120 parts that contains in this design and for A part is about 21 parts. The
design efficiency for this design is 18%. The handling ratio is 7.6 and for assembly ratio
is about 4.8. According to this result, this design needs to be redesigned because it does
not achieve the criteria in Lucas Hull theory.
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38
TeamSET - Assembly ReportGrass Cutting Machine
1-Jan-2008 - 9:59
Company : UTEM
Assembly : original
Version : 1
Parts : 120
A Parts : 21
Design Efficiency: 18%
Handling score: 160.2
Handling ratio : 7.6
Handling limit : 1.5
Assembly score: 100.0
Assembly ratio : 4.8
Assembly limit : 1.5
Work Holder Insertion Remove Tool / DisassemblySecondary Op
Insert Tool / Reassembly Wrong Way Round
No. Part Name Qty. FA A's B's MA Hand. Assembly Flow
1 G.C.M
2 upper tunnel
3 7 A 1 6 - 1.1 nut 2.1
4 14 B 0 14 - 1.3 washer 2.1 2.1
5 7 A 1 6 - 1.1 bolt 4.1
6 1 A 1 0 - 1.1 safety guard 1.1
7 rod
8 8 A 1 7 - 1.1 allenkey screw 4.1
9 8 A 1 7 - 1.1 nut 2.1 2.1
10 16 B 0 16 - 1.3 washer 2.1 2.1
11 2 A 1 1 - 1.6 blade 2.1
12 1 1.1 rod 14.6
1.1
13 bearing
14 2 A 1 1 - 1.1 bolt 4.0
15 2 A 1 1 - 1.1 nut 2.0 2.0
16 4 B 0 4 - 1.3 washer 2.0 2.0
17 1 A 1 0 - 1.3 bearing holder 1.0
18 1 1.0 bearing 13.0
1.0
19 1 1.7 upper tunnel 41.2
2.1
20 lower tunnel
21 4 A 1 3 - 1.1 bolt 4.0
22 4 A 1 3 - 1.1 nut 2.0 2.0
23 8 B 0 8 - 1.3 washer 2.0 2.0
24 1 1.7 lower tunnel 12.0
1.0
25 base
26 bearing
27 1 A 1 0 - 1.3 bearing holder 1.0
28 2 A 1 1 - 1.1 bolt 4.0
29 2 A 1 1 - 1.1 nut 2.0 2.0
30 4 B 0 4 - 1.3 washer 2.0 2.0
31 1 1.0 bearing 13.0
1.0
32 motor
33 4 A 1 3 - 1.1 bolt 4.1
34 4 A 1 3 - 1.1 nut 2.1 2.1
35 8 B 0 8 - 1.3 washer 2.1 2.1
36 1 A 1 0 - 1.0 plug 1.0
37 1 A 1 0 - 1.6 cabel 1.0
38 1 1.7 motor 14.5
2.1
39 1 A 1 0 - 1.6 v-belt 1.0
40 pulley
41 2 A 1 1 - 1.1 screw 4.0
42 2 1.2 pulley 8.0
2.1
43 1 1.5 base 41.7
1.0
44 1 3.0G.C.M 99.0
1.0
Figure 3.12: TeamSET analysis for existing product
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39
CHAPTER 4
RESULT AND ANALYSIS
4.1 Introduction of analysis
This chapter focused on the analysis based on product selected that is grass cutting
machine. The analysis will be done by using the approach of Design for Manufacturing
and Assembly (DFMA) methodology. DFMA is a systematic approach that reduced
manufacturing costs by reducing the total number of individual parts in a product for ease
of handling and insertion. To fulfill this analysis, TeamSET software had been selected
by Lucas Hull approached. The analysis will concentrate based on the design efficiency,
handling ratio and fitting ratio for existing product and also for redesign product.
SolidWork is used for draw the detail drawing of design.
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40
4.2 Draw design using SolidWork software
SolidWork is the one of the 3D design software that can find in the market. In addition, in
SolidWork 3D models and 2D drawings communicate. Users can easily generate
drawings from a model. And when a change in either a drawing or model occurs, all
related drawings and models update automatically. Working in SolidWorks went very
quickly and gave a lot of satisfaction. Photorealistic renderings and animations that allow
communicating how future products will look and perform early in the development
cycle.
4.2.1 Detail drawing of first redesign
TOP VIEW SIDE VIEW
FRONT VIEW ISOMETRIC VIEW
Figure 4.1: View of first redesign
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41
4.2.2 Detail drawing of second redesign
TOP VIEW SIDE VIEW
FRONT VIEW ISOMETRIC VIEW
Figure 4.2: View of second redesign
-
42
4.3 Analysis using TeamSET software
TeamSET is PC based software that functionally to help designer to do redesign product
and it base of Lucas Hull DFA method. This method has been explained at chapter two.
Five contents at this software that related to DFA analysis is such as functional analysis,
manufacturing analysis, handling analysis, fitting analysis and assembly analysis. By
using this software, three designs will be analyze such as existing design, first redesign
and second redesign. Before start perform any analysis using this software, the first step
need to taken is create the flow chart for each design. Then the analysis can carried out by
refer to the flow chart.
4.3.1 DFA analysis for first redesign
The list below showed the part after redesign existing product. A few parts from the
existing product had been eliminate or combined with other parts. The list of the first
redesign is illustrated in table 4.1.
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43
Table 4.1: Quantity List of a first redesign
Ref
No
Description
Quantity
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Upper tunnel
Lower tunnel
Lock
Safety guide
Rod
Bolt 17x76
Allenkey screw
Nut D10mm
Nut D 12mm
Washer D22mm
Washer D13mm
Blade
Bearing D80mm
Bearing holder
Base
Motor
Plug
Cable
v-belt
pulley
screw
1
1
2
1
1
8
4
4
12
12
8
1
2
2
1
1
1
1
1
2
2
Total parts 69
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44
4.3.1.1 Flow chart of first redesign
First redesign can be divided to three main parts as follow: -
a) Upper tunnel part
b) Lower tunnel part
c) base part
Figure 4.3: A flow chart of first redesign main part
4.3.1.2 Flow chart of upper tunnel part after first redesign
Upper tunnel part had eleven sub-parts as follow: -
a) Nut D10mm
b) Nut D12mm
c) Bolt 17x76mm
d) Washer D13mm
e) Washer D22mm
f) lock
g) Safety guide
h) Rod
i) Blade
j) Allenkey screw
k) Bearing
l) Bearing holder
First redesign
Upper tunnel
part
Base part Lower tunnel
part
-
45
Figure 4.4: A flow chart of upper tunnel part after redesign
4.3.1.3 Flow chart of lower tunnel part after first redesign
Lower tunnel part had two sub-parts as follow: -
a) nut
b) bolt 17x
Figure 4.5: A flow chart of lower tunnel part after redesign
Lower tunnel part
Nut Bolt
Nut
D12mm
Upper tunnel
part
Bolt
17x76
Washer
D13mm
Blade Allenkey
screw
Bearing
holder
Rod
Safety
guide
Bearing
Nut
D10mm
Lock
Washer
D22mm
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46
4.3.1.4 Flow chart of base part after first redesign
Base part had eleven sub-parts as follow: -
a) Nut D12mm
b) bolt 17x76mm
c) washer D22mm
d) bearing
e) bearing holder
f) v-belt
g) pulley
h) motor
i) plug
j) cable
k) screw
Figure 4.6: A flow chart of base part
Nut
D12mm
Base part
Bolt
17x76mm
Washer
D22mm
Cable
Screw
Bearing
holder
Motor
V-belt
Bearing
Pulley
Plug
-
47
4.3.1.5 TeamSET analysis for first redesign
TeamSET - Assembly ReportGrass Cutting Machine
1-Jan-2008 - 10:17
Company : UTEM
Assembly: redesign
Version : 1
Parts : 69
A Parts : 20
Design Efficiency: 29%
Handling score: 92.2
Handling ratio : 4.6
Handling limit : 1.5
Assembly score: 85.6
Assembly ratio : 4.3
Assembly limit : 1.5
Work Holder Insertion Remove Tool / DisassemblySecondary Op
Insert Tool / Reassembly Wrong Way Round
No. Part Name Qty. FA A's B's MA Hand. Assembly Flow
1 G.C.M
2 upper tunnel
3 2 A 1 1 - 1.0 lock 1.0
4 1 A 1 0 - 1.1 safety guard 1.1
5 rod
6 4 A 1 3 - 1.1 allenkey screw 4.1
7 4 A 1 3 - 1.1 nut D10mm 2.1 2.1
8 8 B 0 8 - 1.3 washer D13mm 2.1 2.1
9 1 A 1 0 - 1.6 blade 2.1
10 1 1.1 rod 14.6
1.1
11 bearing
12 2 A 1 1 - 1.1 bolt 17x76mm 4.0
13 2 A 1 1 - 1.1 nut D12mm 2.0 2.0
14 4 B 0 4 - 1.3 washer D22mm 2.0 2.0
15 1 A 1 0 - 1.3 bearing holder 1.0
16 1 1.0 bearing 13.0
1.0
17 1 1.7 upper tunnel 31.8
2.1
18 lower tunnel
19 4 A 1 3 - 1.1 bolt 17x76mm 4.0
20 4 A 1 3 - 1.1 nut D12mm 2.0 2.0
21 1 1.7 lower tunnel 8.0
?
22 base
23 bearing
24 1 A 1 0 - 1.3 bearing holder 1.0
25 2 A 1 1 - 1.1 bolt 17x76mm 4.0
26 2 A 1 1 - 1.1 nut D12mm 2.0 2.0
27 4 B 0 4 - 1.3 washer 2.0 2.0
28 1 1.0 bearing 13.0
1.0
29 motor
30 4 A 1 3 - 1.1 bolt 17x76mm 4.1
31 4 A 1 3 - 1.1 nut D12mm 2.1 2.1
32 4 B 0 4 - 1.3 washer 2.1 2.1
33 1 A 1 0 - 1.0 plug 1.0
34 1 A 1 0 - 1.6 cabel 1.0
35 1 1.7 motor 14.5
2.1
36 1 A 1 0 - 1.6 v-belt 1.0
37 pulley
38 2 A 1 1 - 1.1 screw 4.0
39 2 1.2 pulley 8.0
2.1
40 1 1.5 base 41.7
1.0
41 1 3.0G.C.M 84.6
1.0
Figure 4.7: TeamSET analysis for improvement design
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48
Figure 4.7 shows the analysis of first redesign using TeamSET software. The result
shows about 69 parts that contains in this design and for A part is about 20 parts. The
design efficiency for this design is 29%. The handling ratio is 4.6 and for assembly ratio
is about 4.3. According to this result, this design needs to be redesigned because it does
not achieve the criteria in Lucas Hull theory.
4.3.2 DFA analysis for second redesign
The list below showed the part after redesign again. A few parts from the improvement
design had been eliminate or combined with other parts. The list of the final design is
illustrated in table 4.2:
Table 4.2: Quantity List of a second redesign
Ref No
Description
Quantity
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Motor
Bolt 17x76
Bolt 17x25
Base structure
Bearing D20mm
Bearing D24mm
Bush D83mm
Bush D60mm
Shaft blade
Screw 8x12mm
Screw 8x18mm
Cylinder blade
Tunnel
Pulley D50mm
Pulley D88mm
Shaft connector
Key
V-belt
1
4
2
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
Total parts 24
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49
4.3.2.1 Flow chart of second redesign
Second redesign can be divided to four main parts as follow: -
a) Base structure part
b) Cylinder blade part
c) Tunnel part
d) V-belt part
Figure 4.8: A flow chart of final design main part
4.3.2.2 Flow chart of base structure part
Base structure part had two sub-parts as follow: -
a) Motor system
b) Bolt 17x76mm
Figure 4.9: A flow chart of base structure part
Base structure part
Motor system Bolt 17x76mm
Second redesign
Base structure
part
Pulley
system part
Cylinder blade
part Tunnel part
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50
4.3.2.3 Flow chart of cylinder blade part
Cylinder blade part had six sub-parts as follow: -
a) Bearing D20mm
b) Bearing D24mm
c) Bush D83mm
d) Bush D60mm
e) Shaft blade
f) Screw 8x12mm
Figure 4.10: A flow chart of cylinder blade part
4.3.2.4 Flow chart of tunnel part
Tunnel part only had one sub-part. The sub-part is bolt 17x25mm. The only main part
that had more than one part needs to make flow chart. That mean, no need to make flow
chart for this part.
Shaft
blade
Cylinder blade
part
Bearing
D20mm
Bearing
D24mm
Screw
8x12mm
Bush
D83mm
Bush
D60mm
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51
4.3.2.5 Flow chart of pulley system part
V-belt part had five sub-parts as follow: -
a) Pulley D50mm
b) Pulley D88mm
c) Shaft connector
d) Screw 8x18mm
e) Key
Figure 4.11: A flow chart of V-belt part
4.3.2.6 TeamSET analysis for second redesign
Figure 4.12 shows the analysis of second redesign using TeamSET software. The result
shows about 24 parts that contains in this design and for A part is about 18 parts. The
design efficiency for this design is 75%. The handling ratio is 2.1 and for assembly ratio
is about 2.4. According to this result, this design no needs to be redesigned because it
achieves the criteria in Lucas Hull theory. A good design is considered when design
efficiency over 60%, handling ratio less than 2.5 and assembly ratio less than 2.5.
Shaft
connector
V-belt part
Pulley
D50mm
Screw
8x18mm
Key Pulley
D88mm
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52
TeamSET - Assembly ReportGrass Cutting Machine
27-Mar-2008 - 1:09
Company : DEFAULT
Assembly: final design
Version : 1
Parts : 24
A Parts : 18
Design Efficiency: 75%
Handling score: 37.3
Handling ratio : 2.1
Handling limit : 1.5
Assembly score: 44.0
Assembly ratio : 2.4
Assembly limit : 1.5
Work Holder Insertion Remove Tool / DisassemblySecondary Op
Insert Tool / Reassembly Wrong Way Round
No. Part Name Qty. FA A's B's MA Hand. Assembly Flow
1 base ass
2 1 A 1 0 - 1.5 motor 1.0 1.0
3 4 A 1 3 - 1.1 bolt 17x75 4.0
4 1 A 1 0 - 3.0 base 1.51.0
5 1 3.0base ass 8.5
1.0
6 cylinder blade ass
7 1 A 1 0 - 1.0 bearing D20mm 1.7 1.1
8 1 A 1 0 - 1.0 bearing D24mm 1.7
9 1 A 1 0 - 1.0 bush D83mm 2.4
10 1 A 1 0 - 1.0 bush D60mm 2.4
11 1 A 1 0 - 1.5 shaft blade 1.1
12 2 A 1 1 - 1.1 screw 8x12mm 4.0
13 1 A 1 0 - 1.5 cylider blade 1.1
14 1 1.5cylinder blade ass 15.5
1.0
15 tunnel ass
16 1 A 1 0 - 1.5 tunnel 1.0
17 2 A 1 1 - 1.1 bolt 17x25 4.1
18 1 1.5tunnel ass 5.1
1.0
19 V-belt ass
20 1 A 1 0 - 1.1 pulley D50mm 1.1
21 1 A 1 0 - 1.1 pulley D88mm 1.1
22 1 A 1 0 - 1.5 shaft connector 1.1
23 2 A 1 1 - 1.1 screw 8x18mm 4.0
24 1 A 1 0 - 1.0 key 1.7
25 1 A 1 0 - 1.6 v-belt 1.8
26 1 1.0V-belt ass 10.8
1.1
Figure 4.12: TeamSET analysis for second redesign
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53
4.4 Material and process selection
Selection of materials for the part machine is very important. Only part that had been
redesign need to identify such as follow:-
a) Shaft connector
b) Shaft blade
c) Cylinder blade
d) Base structure
e) Tunnel
4.4.1 Shaft blade and shaft connector
A shaft blade is functionally to rotate the cylinder blade and shaft connector used to
connect the shaft blade with pulley. Material that used for shaft blade and shaft connector
is mild steel cylinder. Diameter of the mild steel cylinder is 35mm x 500mm.
manufacturing process that involved is turning process.
Shaft blade shaft connector
Figure 4.13: drawing of shaft blade and shaft connector
\
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54
4.4.2 Cylinder blade
A cylinder blade is a mechanical device for cut the grass. Its will assemble with shaft
blade. Material that used for cylinder blade is mild steel plate with thickness 3mm and
cylinder hollow steel with diameter 34mm. The first machining process involved in this
fabrication is cutting material by using speed cutter machine and laser cutting machine.
Speed cutting machine used to cut the cylinder hollow steel and laser cutting machine is
used to cut the mild steel plate. After cutting process complete and final step is to
welding process by using metal inert gas welding machine (MIG).
FRONT VIEW SIDE VIEW
ISOMETRIC VIEW
Figure 4.14: View of cylinder blade
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55
4.4.3 Base structure
Base structure is purpose to support motor, tunnel and cylinder blade. Base structure can
be divided into two sections such as mounting and structure. The processes that involved
are cutting process, milling process, drilling process and welding process. Material that
used for mounting is mild steel plate with thickness 20mm and for structure used angle
iron steel with thickness 3 mm. Two type of machines that involved in cutting process
which are laser cutting machine and speed cutting machine. Miling machine is a machine
tool used for the complex shaping of metal and other solid materials. Its basic form is that
of a rotating cutter or end mill which rotates about the spindle axis (similar to a drill), and
a movable table to which the work piece is affixed.Milling process is used to make
counter bore at the mounting. Diameter of counter bore is 66mm for left side and 86mm
for the right side. Welding process is for joint all part together by using metal inert gas
welding machine (MIG). Last process that involved is drilling process by using drilling
machine.
Figure 4.15: View of base structure
Mounting
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56
4.4.4 Tunnel
Tunnel is purpose to cover cylinder blade and mounting. Material that used for fabricate
tunnel is mild steel plate with thickness 3mm. The process that involved in producing this
part is cutting process, bending process, welding process and drilling process. Cutting
process is for cut material according to dimension specification. The machine that
involved in this process is laser cutting. After cutting process had been done the next
process is the bending process. This process used bending machine to fabricate the part.
Figure 4.16: cross section view of tunnel
Figure 4.17: isometric view of tunnel
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57
CHAPTER 5
DISCUSSION
5.1 Comparison of existing design with first and second redesign
The TeamSET approached had been used thoroughly in this project. With TeamSET
software analysis, the result was very useful especially for manufacturer to study about
their products. Beside, the software also managed to detect the problem or unimportant
part which can be eliminated. According to the table 5.1 and table 5.2, the second design
more improve if compared with first design. The part reduction for second redesign is
80% improvement. This mean part reduction for second redesign is higher than part
reduction for first design. Handling ratio is the total handling score divided by the count
of A parts. The handling ratio for existing design is 7.6. In the other hand, handling
ratio for existing design not achieve the criteria in Lucas hull theory so its need to
redesign. After first redesign, the handling ratio still not achieves criteria in Lucas hull
theory but the handling ratio reduction improves to 39.47%. First redesign needs to
redesign again until its achieve all criteria in Lucas hull theory. After second redesign,
the handling ratio is 2.1 and its less than 2.5. Second redesign is considering as a good
design. Handling ratio improvement for second redesign is 72.37% and assembly ratio
improvement for second redesign is 50%.
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58
Table 5.1: Comparison of existing design with fisrt redesign
Existing design First redesign Improvement %
Total parts 120 69 42.5%
Handling ratio 7.6 4.6 39.47%
Assembly ratio 4.8 4.3 10.41%
Design efficiency 18% 29% 11%
Table 5.2: Comparison of existing design with second redesign
Existing design second redesign Improvement %
Total parts 120 24 80%
Handling ratio 7.6 2.1 72.37%
Assembly ratio 4.8 2.4 50%
Design efficiency 18% 75% 57%
According to the analysis that has been done, the analysis show that second redesign is
the best design because this design achieve all the criteria in Lucas hull theory. The
design efficiency for second redesign is over than 60%. The handling ratio and assembly
ratio for second redesign is less than 2.5. If the design not achieves one of these three
criteria the design should be reconsidered before continuing the following analysis.
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59
5.2 Safeguards for prevent from mechanical hazards
The workplace with moving machine parts can be a very dangerous place for users.
Various mechanical hazards need a good of machine safeguarding. In ideal case any
mechanical motion that threatens a users safety should not remain unguarded. Crushed
hands and arms, severed fingers, blindness are among the list of possible machinery-
related injuries. Safeguards are thus essential for protecting users from uncalled-for and
preventable injuries. The safeguards for the redesign product are such as:
a) Funnel
b) Rubber protector
c) Cover belting system.
FUNNEL RUBBER PROTECTOR
COVER BELTING SYSTEM
Figure 5.1: Part for accessories
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60
TOP VIEW ISOMETRIC VIEW
FRONT VIEW SIDE VIEW
Figure 5.2: View of the second redesign after installation accessories
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61
CHAPTER 6
CONCLUSION & FUTURE WORKS
6.1 Conclusion
As a conclusion, this PSM project had been successfully implemented by fulfilling the
requirement as being expend. Beside, the project also achieved the objective in order to
redesign the product and achieved the better design efficiency, handling ratio, and fitting
ratio compared both existing product and redesign. In addition, it was very useful to be
exposed with the use and application of Design for Manufacturing and Assembly
(DFMA) methodology that might very useful to me while facing the real working field in
future undertaking. Lastly, the application of DFMA methodology will be the best
method or approach for nowadays industries to be applied in achieving the bright future.
Figure 6.1: Shows the comparison between existing product and second redesign
Existing
product
120 parts
second
redesign
24 parts
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62
6.2 Future works
For this Projek Sarjana Muda, the study was focused more on implantation of DFMA
methodology, and finally came out with a new design of grass cutting machine. Actually,
there are many ways or phases that this project could be done. So, for future works, I
recommended some methods that can be done as follows:
a) Use Morphological Chart method to identify the alternative mechanism
and operation system of the grass cutting machine to be developed.
b) Study the overall costing for design grass cutting machine that had been
developed.
c) Concept Convergence method to analyze and select the best alternatives
based on the quantitative assessment.
d) For student who use DFMA methodology, they sould have collaboration
with industry in order to gain more knowledge, information, and the
technical requirements regarding DFMA implementation.
With all this recommendations, hope that the further study will become more effective
and lead to better result.
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63
REFERENCES
Alan F and Jan Chal(1994), Design for Assembly, Principles and Practice. McGraw
HILL BOOK COMPANY, 1994
G. Boothroyd and W. Knight (1993), Manufacturing La Carte: Efficiency:Design for
assembly, IEEE Spectrum., pp. 51-53.
G. Causey (1999), Elements of agility in manufacturing, Ph.D. Dissertation
(Mechanical Engineering), CWRU, January 1999.
Xiaofan Xie (2003) Design for Manufacture and Assembly Dept. of Mechanical
Engineering, University of Utah : PhD thesis.
Vincent Chan and Filippo A. Salustri (2005). Lucas Hull Method [online]. Available :
http://deed.ryerson.ca/~fil/t/dfmlucas.html [October 2007]
D-ESPAT (2007). Apache Reengineering [online] Available:
http://www.despat.com/CS%20-%20Aerospace.html [ December 2007]
TeamSet (2008) TeamSet [online] Available:
http://www.softscout.com/software/Engineering/MechanicalEngineering/TeamSET.ht
ml [January 2008]
David Grieve (2003) Design for Manufacture [online] Avaiable:
http://www.tech.plym.ac.uk/sme/TSOC302/desman1.htm [January 2008]
TeamSet (2008b).Motor Coach Overhead Luggage Rack [online] Avaiable:
http://www.teamset.com/frame2.html [January 2008]
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64
Shih-Wen Hsiao (2001) Concurrent design method for developing a new product.
Department of Industrial Design, National Cheng Kung University, Taiwan. PhD
thesis.
Anonymous (1998) TeamSet user guide version 3. CSC Computer Sciences Ltd. (CSC)
Serope Kalpakjian and Schmid, S. R. (2001). Manufacturing Engineering and
Technology. 4th ed. New Jersey: Prentice-Hall.
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APPENDIX A
-
Gant chart PSM 1
Activity W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
Research title confirmation
Understanding research scope and objectives
Finding literatures (books, journals, articles)
that related to research title.
Report writing on Introduction
Report writing on Literature Review
Report writing on Methodology
Checking and editing report
Report submition
-
Gant chat PSM 2
Activity W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
Analysis data for existing product using
TeamSet
Draw the redesign of existing product using
SolidWork
Analysis data for redesign of existing product
using TeamSet
Best redesign concept
Design for manufacture
Report writing
Checking and editing report
Report submition
-
APPENDIX B
-
Design and Development of Grass Cutting machine using DFMA
Methodology
Mohd Ishammudin Bin Mohd Yunus
Faculty of Manufacturing Engineering,
Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Melaka
Phone: +6017-6369430, Email: [email protected]
Abstract-This ptoject describes about the
implementation of redesign the grass cutting machine
by using the application of Design for Manufacturing
and Assembly (DFMA) methodology. The scope
based on the existing grass cutting machine and the
appropriate of DFMA methodology. The method used
for gaining the data is from the reassembled the
existing grass cutting machine. From the data
achieved, it can be classified into several categories to
be studied. Data will be analyzed by using Lucas Hull
method to verify the design efficiency, handling ratio
and fitting ratio to achieve. The tools that used is
TeamSET software. The new propose