UNIVERSITI TEKNIKAL MALAYSIA MELAKA

LIFE CYCLE AND SUSTAINABILITY OF DESIGN ON RTV

SILICONE RUBBER MOULD

This report submitted in accordance with requirement of the Universiti Teknikal

Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering

(Manufacturing Design) with Honours.

by

NUR HIDAYAH BINTI AMIR

FACULTY OF MANUFACTURING ENGINEERING

April 2009

LIFE CYCLE AND SUSTAINABILITY OF DESIGN ON

RTV SILICONE RUBBER MOULD

NUR HIDAYAH BINTI AMIR

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

i

ABSTRACT

The design and manufacturing of mould in Rapid Manufacturing represent a significant

link to the accuracy, durability, finishing and the amount of parts that the mould can

duplicate. One of the main problems with RTV Silicone mould is to determine how long

the mould can sustain before breaking down. This research is about Life cycle and

sustainability of RTV Silicone mould that will look at the process in developing the

RTV Silicone mould, the dimensional accuracy of the duplicate parts and also the

factors that affect the longevity and sustainability of RTV silicon rubber mould. Pilot

sampling has been done on 7 samples to obtain a stable data and to familiarize with the

method of data collection. After that, 30 parts were produced from this mould and

measurements are taken for each of the parts. It was found that the more the mould

duplicate the part, the dimensional accuracy of the part tend to loose.

ii

ABSTRAK

Rekabentuk dan pembuatan acuan di dalam pembuatan terpantas menggambarkan

hubungan yang penting dengan ketepatan, ketahanan, penghabisan dan jumlah bahagian

yang mampu diduplikasi oleh acuan. Salah satu daripada masalah utama acuan silikon

yang mampu mengeras dalam suhu bilik ialah ia hanya mampu menampung tuangan

dalam jumlah yang kecil sebelum tidak dapat digunakan lagi. Projek ini adalah tentang

putaran hayat dan ketahanan rekabentuk terhadap acuan silikon yang mampu mengeras

dalam suhu bilik dan akan melihat proses-proses yang terlibat dalam pembuatan acuan

ini, ketepatan ukuran setiap bahagian yang diduplikasi dan faktor-faktor yang

memepengaruhi jangka hayat dan ketahanan acuan. Sebanyak 7 sampel awal telah diuji

untuk mendapatkan data yang stabil dan untuk membiasakan dengan cara pengumpulan

data. Kemudian sebanyak 30 bahagian telah dihasilkan daripada acuan tersebut dan

ukuran untuk setiap satu bahagian diambil. Bacaan data menunjukkan semakin banyak

bahagian yang dihasilkan daripada acuan, ketepatan bacaan untuk setiap bahagian akan

semakin kurang.

iii

DEDICATION

For my dearest mom and dad.

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ACKNOWLEDGEMENT

This research was performed under the supervision of Mdm Ruzy Haryati Hambali and

Mr Hassan b Attan, whom I would like to thank for the freedom granted in carrying out

this project. I also would like to express my deep appreciation to both of them for

understanding regarding the difficulties I had during the project.

I would like to gratefully acknowledge Mr Mohd Fairus b Ninggal for his consultation

and for providing equipment that was required.

A special thank to all my friends who have worked together for our projects. I could not

achieve it without their support and encouragement.

Most of all, I would like to thank my parents for their patience and support through all

the years.

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TABLE OF CONTENT

Abstract……………………………………………………………………………….….i

Abstrak…………………………………………………………………………………..ii

Dedication……………………………………………………………………….………iii

Acknowledgement……………………………………………………………….………iv

Table of Content……………………………………………………………….…………v

List of Tables………………………………………………………………….…………ix

List of Figures…………………………………………………………………………….x

List of Abbreviations…………………………………………………………………....xii

1. INTRODUCTION……………………………………………….……….………1 1.1 Background…………………………………………………………………………...1

1.2 Problem Statement……………………………………………………………………2

1.3 Objective of the Research…………………………………………………………….4

1.4 Scope of Work………………………………………………………………………..4

2. LITERATURE REVIEW………………………………………………………5 2.1 Life Cycle………………………………….…………………………………………5

2.1.1 Life Cycle Analysis………………………………………………………...………6

2.1.1.1 How does LCA Works? ……………………………….…..…………………….6

2.1.1.2 Component of LCA………………………………………………………………7

2.1.2 Life Cycle Management…………..………………………………………………10

2.1.3 Why Life Cycle Management useful………………………………………….… 11

2.1.4 Drivers for the adoption of Life cycle management………………………………12

2.1.4.1 Key Drivers……………………………………………………………………..12

2.1.4.2 UNEP Life Cycle Initiative……………………………………………….…….13

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2.2 Sustainable product…………………………………………………………………14

2.2.1 The Characteristic of Sustainable Product design……………………………...…15

2.2.2 Drivers for more Sustainable Design……………………………………….…….15

2.3 Room Temperature Vulcanizing (RTV) Silicone……………….…………………..18

2.3.1 Characteristics of RTV Silicone Rubber………………………………………….19

2.3.2 Making Silicone Rubber Mould…………………………………………….…….26

2.3.3 Bonding…………………………………………………………………………...27

2.3.4 Diluent……………………………………………………………………….……31

2.3.5 Causes of Poor Mould making and Solutions…………………………………….32

2.4 Vacuum Casting………………………………………………………………..…..35

2.5 Rapid Tooling Background Information……………………………………………37

2.5.1 Introduction to Rapid Tooling…………………………………………………….37

2.5.2 Classification of Rapid Tooling Methods…………………………………………37

2.5.2.1 Indirect Methods of Rapid Tooling…………...………………………………...41

2.5.2.2 Direct Methods of Rapid Tooling…………….…………………………………42

2.5.3 Appropriate Rapid Tooling Selection………………….………………………….45

2.6 Rapid Prototyping Background Information……………………………….…….…48

2.6.1 Introduction to Rapid Prototyping…………………………….………….……….48

2.6.2 Application of Rapid Prototyping……………………………………….………..50

2.6.3 Classification of Rapid Prototyping………………………..……….……….……50

2.6.3.1 Liquid-based Systems….……………………………………….….……….,…..51

2.6.3.2 Solid-based Systems………………………………………….….…………..….51

2.6.3.3 Powder-based Systems…………………………………….……….……….…..52

2.6.4 Basic processes of Rapid Prototyping…………………….….……………….…..52

2.6.5 3D Printer……………………………………………………..………………..…54

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3. METHODOLOGY…………………………………………………….59 3.1 Introduction…………………………………………………………………………59

3.2 Description of Methodology………………………………………………………..62

3.2.1 Project Proposal and Search for Project Information……………………………..63

3.2.2 Virtual Prototyping Introduction………………………………………………….63

3.2.2.1 Virtual part Design of Master Pattern…………………………………………..63

3.2.2.2 Master Pattern…………………..………….……………………………………64

3.2.3 Physical Prototyping………………………………………………………………65

3.2.4 Rapid Tooling……………………………………………………………………..65

3.2.5 Validation…………………………………………………………………………65

3.2.6 Investigation on mould degradation………………………………………………66

3.3 Mould Development………………………………………………………………...66

3.3.1 Design of the mould………………………………………………………………66

3.3.2 Riser and Runner………………………………………………………………….67

3.3.3 Modeling Clay Parting Line……………………………………………………....67

3.3.4 Calculation of Required Silicon…………………………………………………..68

3.3.5 Positioning the Part…………………………………….………………………….69

3.3.6 Material of the Mould………………………………….………………………….69

3.3.7 Vacuum Oven………………………………………….………………………….70

3.3.8 Pouring the Molding Material…………………………….………………………72

3.3.9 Demold and Cutting the Mould…………………………..……………………….72

3.3.10 Duplicating Process…………………………………….….…………………….73

3.3.11 Placing the Mould……………………………………….……………….………74

3.3.12 Material of Casting…………………………………….….……………………..75

3.3.13 Preparation of Mixture………………………………….……………………….75

3.3.14 Pouring the Material…………………………….……………………………….75

3.3.15 Removing the Pattern……………………………………………………………76

3.4 Dimensional Accuracy……………………………………………………………...77

3.4.1 Numerical Information……………………………………………………………78

3.4.2 Dimensional Accuracy Measuring Information…………………………………..79

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4. RESULTS……………………………………………………….….….80 4.1 Data for Pilot Test…………………………………………………………….…….80

4.2 Data for Dimensional Accuracy……………………………………………….……82

5.DISCUSSION………………………………………………………......84 5.1 Dimensional Accuracy Analysis………………………………………………..…..84

5.2 Physical Testing Analysis………………………………………………….….…….92

6. CONCLUSION…………………………………………….…….…….93 6.1 Conclusion…………………………………………………………….……...……..93

6.2 Future Work Recommendation………………………………………….…….……94

REFERENCES………………………………………………………………….…..95

APPENDIX A……………………………………………………………………..……99

APPENDIX B…………………………………………...…………………………….100

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LISTS OF TABLES

Table 2.1 : General Characteristics…………………………………………………….21

Table 2.2: Typical example of mould making………………………………………….23

Table 2.3: To bond RTV silicone rubber to different material………………………...28

Table 2.4: Primers for two-component RTV silicone mould…………………………..29

Table 2.5: Typical silicone rubber bonding agents…………………………………….30

Table 2.6: Causes of Poor Mouldmaking and Solutions……………………………….32

Table 2.7: Commercially Available Indirect Tooling Processes………………….…..43

Table 2.8: Commercially Available Direct Tooling Processes………………………..44

Table 4.1: Pilot Test Measurement for Dimensional Accuracy………………………...80

Table 4.2: Pilot Test Measurement for Physical Testing……………………………….81

Table 4.3: Results for Dimensional Accuracy………………………………………….82

Table 4.4: Results for Physical Testing…………………………………………...……82

x

LISTS OF FIGURES

Figure 2.1 : Life Cycle of Product……………………………………………………….5

Figure 2.2 : The Product Life Cycle….………………………………………………….7

Figure 2.3 : Phases of an LCA…………………………………………………………..9

Figure 2.4 : Chain of Product’s material sustainability……..…………………………14

Figure 2.5 : Method of making a Silicone Rubber mould using the Vacuum Pouring

Methods……………………………………………………………………27

Figure 2.6 : Methods of Use…………………………………………………………..28

Figure 2.7 : Amount of RTV thinner added in physical properties……………...……..31

Figure 2.8 : Vacuum Casting process………………………………………….……….36

Figure 2.9 : Comparison of Rapid Prototyping to Rapid Tooling…………….…..……37

Figure 2.10: Architecture of the RTV Integrated Manufacturing Systems….…………40

Figure 2.11: Classification scheme for Rapid Tooling Process……..………….………41

Figure 2.12: The use of RP system in different sectors………………….….………….42

Figure 2.13: Classification of Rapid Tooling process………………………….………50

Figure 2.14: Flow Chart of RP Technology……………………………………………54

Figure 3.1 : Process flow chart of Experimental Design of Experiment……………61

Figure 3.2 : Master Pattern Isometric View…………………………………………..64

Figure 3.3 : Component of the mould……………………..…………………………66

Figure 3.4 : Location of the riser and runner from top position………………………67

Figure 3.5 : Master pattern in modeling clay……………………………………...…68

Figure 3.6 : Case for mould……………………………………………………...……69

Figure 3.7 : The two components of Silicon and Hardener mixed by stirrer……….70

Figure 3.8 : Container inside the Vacuum Machine…………………………………..71

Figure 3.9 : The condition of the mixture of Silicon and Hardener in Vacuum Machine

for degassing process…………………………………………………….72

Figure 3.10 : Process of cutting the mould by using the knife and the separator………73

Figure 3.11 : Major component in duplication process………………………………..74

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Figure 3.12 : The mould with the runner attached to it……………………..………….74

Figure 3.13 : Process of pouring the material inside the mould…………….………….76

Figure 3.14 : Removal of duplicate part after fully cured…………………….………..76

Figure 3.15 : Basic geometry dimension for the original part……………….…………78

Figure 3.16 : Micrometer………………………………………………….……………79

Figure 3.17 : Profile Projector…………………………………………….……………79

Figure 5.1 : Graph length 1 versus number of parts…………………….…………….85

Figure 5.2 : Graph length 2 versus number of parts…………………….…………….85

Figure 5.3 : Graph height versus number of parts……………………….……………87

Figure 5.4 : Graph radius versus number of parts……………………….……………88

Figure 5.5 : Graph Thickness 1 versus number of parts………………………………89

Figure 5.5 : Graph Thickness 2 versus number of parts………………………………89

xii

LIST OF ABBREVIATIONS

ABS - Acrylonitrile-butadiene-styrene

CAD - Computer-aided Design

DSPC - Direct Shell Production Casting

FOM - Fused Deposition Modeling

LENS - Laser-engineered Net Shaping

LOM - Laminated Object Modeling

MJM - Multijet Modeling

MJS - Multiphase Jet Solidification

RP - Rapid Prototyping

RPS - Rapid Prototyping System

RPTM - Rapid Prototyping, Tooling and Manufacturing

RT - Rapid Tooling

RTV - Room Temperature Vulcanizing

SAHP - Selective Adhesive and Hot Pass

SCS - Solid Creation System

SLA - Stereolithography Apparatus

SLS - Selective Laser Sintering

STL - Stereolithography file

1

CHAPTER 1 INTRODUCTION

1.1 Background

Global competition, mass customization, accelerated product obsolescence and

continued demands for cost serving are forcing companies to look for new ways to

improve their business processes. It is now widely accepted that over 70% of final

product costs are determined during design stage. (Pham, D.T., and Dimov, S.S., 2003)

Therefore, it is important to produce a design that use the most optimize cost. Design has

been included in the product life cycle because it will have an influence on all other

parts of the life cycle. Reducing the overall impact by innovative new design is also a

significant opportunity for any company.

Product development involved design, manufacturing, material choices, product type,

use and final disposal. Generally, in mould manufacturing the goal of the manufacturer

is to produce a mould that can have long life cycle and next to sustain it. Here, the

design of the mould plays an important role as it is not only affected the final product

cost but also its life cycle and sustainability.

Rapid prototyping (RP) and rapid tooling (RT) have emerged as key enablers for rapid

manufacturing, a new mode of operation promising improvements to the competitive

position of company adopting it. RP technology for quickly fabricating physical models,

functional prototype and small batches of parts directly from computer aided design

(CAD) data. RT generally concerns the production of moulds and tooling inserts using

RP. (Pham, D.T., and Dimov, S.S., 2003)

2

The RT technique that base on RP offer a rapid and effective method to make mould,

and show a high potential for faster response to market demands. ( Ding, Y. et al, 2003).

With the increase in the technology of rapid prototyping technique, numerous processes

have been developed for producing tooling mold from RP masters. The most widely

employed method of rapid prototyping are to make silicon room temperature vulcanizing

(RTV) moulds for plastic parts and as sacrificial models for investment casting of metal

parts. ( Dickens, P.M. et al, 1995)

The production of room temperature vulcanizing (RTV) silicone rubber moulds has

become one of the most popular types of RT applications and it being used to mold

delicate and low temperature resistance materials. It also use to reproduce complex

forms cast in metal and plastic. RTV silicone is an ideal mold material to use to

reproduce prototypes and create sub masters from fragile, low-temp model materials.

(Wohler, T., 2008) With the arrival of rapid prototyping technique, master pattern are

often made of the RP models themselves.

The direction of this study is to identify the life cycle and sustainability of design on

RTV silicone mould including the number of part the mould can duplicate and the

changing of mould’s physical dimension. Further study will be implemented to prolong

the life cycle of the mould and method to sustain it.

1.2 Problem Statement

There is growing worldwide interest in the improvement of technology in mould making

development by using RTV Silicone. All of the manufacturer and company that involved

in this technology look forward a new ways to improve their business process thus

increasing their profit.

3

Most of the current focus is on reducing the problem of current RTV Silicon mould,

such as:

1. Prolong the life of the RTV Silicon mould

2. Reducing the time and cost by not frequently changing the mould

3. Maintaining/increasing the quality of product by using the mould that has

long cycle time.

One of the key requirements is to improve resource efficiency by assessing:

1. The process of mould preparation.

2. The characteristic of RTV Silicon.

3. Causes of poor mold making and its solution.

4. Number of part being produce on a single RTV Silicon mould.

A typical silicone rubber is usually used for molding the mould which can only support

castings in small batches before breaking down . (Tang, Y. et al, 2007). In addition there

is a need to examine the total life cycle for Silicone rubber mould. This research is about

life cycle and sustainability of design on RTV Silicone mould will look at RTV Silicone

mould through its life cycle and how long it sustains. In order to carry this, method that

will be used is by determining the part that the mould can duplicate and also the mould’s

physical dimension after the duplication process.

4

1.3 Objective of the research

For this project, there are a few aims to achieve during implementation of this project for

this semester such as:

1. To understand the process in developing silicone rubber mould.

2. To study the effect of the dimensional accuracy of the product in determine

the total life cycle of RTV silicon mould.

3. To identify the factors that effect the longevity and sustainability of RTV

silicon mould.

1.4 Scope of Work

The purpose of this project is to understand the process in developing Silicone rubber

mould. The main focus is on the RTV Silicone rubber mould. The life cycle and

sustainability of RTV Silicone rubber mould will be examined. The number of part that

the mould can duplicate, the mould’s physical dimension, and the life of the RTV

Silicone rubber mould will be recorded.

In order to understand the process in developing silicon rubber mould, the mold making

methods is briefly defined and information, concepts, and some contents from previous

research which is related about developing silicon rubber mould is discussed briefly in

this report.

The total life cycle for a silicone rubber mould and its physical dimension are examined

after the mould being produced and the part being duplicated. The cycle time and the

mould life of silicone rubber mould is being recorded and analyzed.

By doing analysis on the total life cycle of the silicone rubber mould, method to

maintain the sustainability of silicone rubber mould can be examined.

5

CHAPTER 2 LITERATURE REVIEW

2.1 Life Cycle Life cycle is a consecutive and interlinked stages of a product or service system, from

the extraction of natural resources to the final disposal. The term “life cycle” refers to

the major activities in the course of the product’s life-span from its manufacture, use,

and maintenance, to its final disposal, including the raw material acquisition required

manufacturing the product. A life cycle is made up of all the activities that go into

making, selling, using, transporting and disposing of a product or service - from initial

design, right through the supply chain. (Anonymous 2008) Figure 2.1 shows the life

cycles of a product.

Figure 2.1 : Life cycles of a product. (Anonymous 2008)

6

2.1.1 Life Cycle Analysis

LCA is defined as identifies the material, energy, and waste flows associated with a

product over its entire life cycle so that the environmental impacts can be determined.

By using LCA, it is possible to evaluate the environmental performance of a product

from ‘cradle to grave’, allowing the most significant environmental impacts associated

with it during its lifetime to be considered, i.e from extracting the raw materials and

fuels from the earth through to the product’s use and disposal. (Hamzah, N.A., 2006).

LCA involves making detailed measurements during the manufacture of the product,

from the mining of the raw materials used in its production and distribution, through to

its use, possible re-use or recycling, and its eventual disposal. LCAs enable a

manufacturer to quantify how much raw materials are used and energy needed, and how

much solid, liquid and gaseous waste is generated, at each stage of the product's life.

(Hari, S., 2008)

2.1.1.1 How does LCA works?

LCA considers the different stages and geographical sites a product will pass through in

its lifetime. LCA avoids the problem of shifting environmental impacts to other parts of

life cycle by using a holistic approach, such as changing the materials use in production

may create less environmental effect at the production site, but increase the

environmental impact. (Bournemouth University, 2005)

LCA also consider the most significant environmental burdens and environmental issues

. Improvements in any one environmental issues, for example global warming, are not

made without considering the impacts on another, such as resource depletion. LCA is a

quantitative technique which has the power to inform decision makers, and therefore

help them to make informed and robust decisions. (Hamzah, N.A., 2006) Figure 2.2

shows the possible life cycle stages that can be considered in an LCA and the typical

inputs/outputs measured.

7

Figure 2.2 : The product life cycle. (Hamzah, N.A., 2006)

2.1.1.2 Components of LCA

The LCA process is a systematic, phased approach and consists of four components:

goal definition and scoping, inventory analysis, impact assessment, and interpretation as

shown in Figure 2.3. The four linked components of LCA are:

1. Goal definition and scoping.

Identifying the LCA's purpose and the expected products of the study, and

determining the boundaries (what is and is not included in the study) and

assumptions based upon the goal definition. The goal and scope can be addressed by

answering a number of questions:

1) What product is the LCA going to deal with?

2) Is the LCA going to compare similar products which differ in their design

and/or manufacturing process, or it is going to assess a single product?

3) Will the LCA involve an assessment of competitors’ product?