VERIFICATION OF PROJECT

I / We· hereby declare that the Report / Thesis has been read and I / We have opinion

that the project paper is appropriate in terms of scope coverage and quality for

awarding a Bachelor in Production Technology.

Signature

Name of Supervisor

Date

Signature

Name of Supervisor II

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A STUDY OF A PROBLEfv1ATIC INJECTION PRODUCT, LEADING TO THE

RE- DESIGN AND IMPROVEMENT OF THE PRODUCT:

STUDY ON RELA T10IIJSHIP MATERIALS, LOCATING GATES AND

TYPES OF MOULD BY MOLDFLO\N ANALYSIS

T.JUL.006

flliOHD FAIRUZ BIN ALIAS

PROJECT SUPERVISOR

!ViR. SCOTT KIRBY

GERMAN MALAYSIAN INSTITUTE

PRODUCTION TECHr~OLOGY DEPARn~ENT

MARCH 2003

OATH

I hereby declare that this project paper is originated from my own idea.

Signature

Name of Student

I.e Number

Date

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11

DEDICATlor~

I vJOuld like to dedicate thiS report to my beloved family and pare'lt~ 1'.':1:) :VWE: t:l(:

confidence in me to overcome all the obstacle on my JOurney to suc:::ess

1\'

ACKhlOWLEDG EME!~T

I wish to express my sincere appreciation to Mr. Scott Kirby the supervisor for

this project for the many hours spent discussing, troubleshooting the problem arise and

checking the draft of the thesis paper. Your assistance was of prime importance in

making the thesis paper complete.

I also greatly appreciate the assistance from a/l the other during the

implementation of this project.

Thank you very much.

v

ABSTRACT

This thesis paper present about proposed simulation of flaw analysis (Moldflow)

of plastic part that has produce by injection moulding method. The part, Cable tie

selected from we idea to study of relationship material, locating gate and type of mould

can be used in this project.

This project intends to review the major problems encountered on the existing

product and propose possible solution to make the product more viable and

competitive. The investigation scope will also include material selection, as it has been

identified as one of major problems uncounted on the existing product. Beside that, in

this study a simulation of flow analysis (Moldflow) has been utilised to investigate filling

image, temperature reaction, weld lines and air trap phenomena in cooperating the

new mould design.

In simulation of flow analysis (Moldflow) we also study on best selected locating

gate. From the result we can do analysis and compared with the other results use

dtfferent locating gate.

TABLE OF COf.JTENT

CHAPTER TITLE

Title of the project

Oath

Dedication

Acknowledgement

Abstract

List of content

List of table

List of symbols and abbreviation

List of appendix

List of figure

Chapter 1 1.0 Introduction

1.1 The Flow Pattern Method Pointed the Way Forward

Chapter 2 2.0 Literature Review

2.1 Cable Ties History

2.2 The First Cable Tie

2.3 Modem Cable Tie

2.4 Cable Tie Characteristics

2.5 Three Types Of Nylon For Specific Applications

2.6 The Need For Plastic Flow Analysis

2.7 Advantages Of Flow Analysis

2.8 Injection Moulding Machine

2.9 The Injection Moulding Process

2.10 Melt Flow Analysis Theory

2.11 The Moldflow Software

Vl

PAGE

ii

iii

iv

v

vi

ix

x

xi

xii

1

1

4

5

5

6

6

7

8

10

12

17

22

Chapter 3 3.0 fVlethodoiogy

3.1 The Model

3.2 Part Geometry

3.2.1 What the Mesh?

3.3 The Analysis

3.3.1 Analysis Divide For The 3 Stage

3.3.2 Step Of Analysis

3.3.3 Material Used

3.3.4 Best Gate Locating

3.3.5 Type Of Mould

3.4 Machine Specification

3.4.1 Processing Parameter

Chapter 4 4.0 Results and Analysis

4.1 Explanation On Software Results Display

4.1 .1 Fill TIme Result

4.1.2 Temperature Result

4.1.3 Pressure Result

4.1.4 Air Trap Result

4.1.5 Weld Line Result

4.1.6 Clamp Force Result

4.1.7 Pressure At Injection Location Result

4.1.8 Shear Stress Result

4.1.9 Freeze Time Result

4.2 Best Material Selection

4.2.1 Injection Result

4.2.2 Comparison Material Result With One

Injection And Two Injections At The Part

4.2.3 Picture Result With One Injection

4.3 Best Locating Gate Analysis

4.3.1 Comparison Locating Gate Result With

Different Material

4.3.2 Comment And Results

4.4 Type Of Mould

4.4.1 Three Plale Moulds

4.4.1.1 Ejector Movement By Stripper Bolt

VII

27

27

30

30

32

32

35

40

41

44

44

45

45

45

46

46

46

46

47

47

47

48

49

50

54 - 55

56 - 58

57

58

58

58

58

viii

Chapter 5 5.0 Discussion

5.1 Fill Time Result 60 5.2 Temperature Result 61

5.3 Instant Temperature Result 61 5.4 Pressure Result 62

5.5 Air Traps Result 62

5.6 Weld Line Result 63 5.7 Clam Tonnage 64

5.8 Sink Mark 64 5.9 Flashing 64 5.10 Part Weight 65

Chapter 6 6.0 Conclusion and Recommendation

6.1 Conclusion 66

6.2 Recommendation 67

7 References 68 8 Appendix 69 - 114

IX

List of Tables

TABLE TITLE I PAGE !

2.1 I

Important considerations for simplifications 23

2.2 Type of flow analysis 26

4.1 Injection Location Results 50

4.2 Best Locating Gate Result 57

CAE

CAD

CAM

STL

IGES

MPI

Deg C

Mm

Mpa

Cucm

G Min

J Kg

Sec

S

List of Symbols and Abbreviations

Computer Aided Engineering

Computer Aided Design

Computer Aided Manufacturing

Stereo lithography

Intemational geometric exchange standard

Moldflow Plastic Insight

Degree Celsius

Millimetre

Mega Pascal

Cubic centimetre

Gram

Minute

Joule

Kilogram

Second

second

x

APPENDIX

2

3

4

5

6

List of Appendix

i nTLE I I

i lOne injection analysis output

Two injection analysis output

Pin point gate analysis output

Edge gate (side) analysis output

Edge gate (front) analysis output

Picture Results For Different Material And Gate

Locating

PAGE

69 75 80 87 93

99

\1

xii

List of Figure

FIGURES TITLE PAGE

1.0 Flow pattern method I

2 2.1 Injection end of reciprocating screw machine 11

2.2 The injection moulding cycle 14

2.3 Viscosity function of cross-linking moulding compound 16

processing limits

2.4 Weld line 18

2.5 Plastic flow behaviour through thin wall 19

2.6 Basic theoretical flow diagram 20

2.7 Translate to Moldflow mesh format 24

3.1 Solid model 28

3.2 Complete system (Edge front gate) 28

3.3 Complete system (Pin Point Gate) 29

3.4 Complete system (Edge side gate) 29

3.5 Fusion (mesh) 30

3.6 3D Solid (mesh) 31

3.7 Midplane (mesh) 31

3.8 Edge Gate (side) 33

3.9 Pin Point gate 34

3.10 Edge gate (front) 34

3.11 Gating layout 40 & 41

3.12 Two plate mould 41

3.13 Three Plate Mould 43

4.1 Injection Location on part 48

4.2 Weld line result 49

4.3 Fill Time Results 51

4.4 Pressure Results 52

4.5 Shear Stress Results 53

4.6 Temperature Results 54

CHAPTER!

1.0 INTRODUCTION

Development work on the simulation of the injection moulding process started in

the mid-1970s when the first simple programs for programmable pocket calculators

became available for calculating the pressure loss in specified flow channels. The

geometry options then available were cylinders for the gate system and plates and

circular segments for the moulded part, depending on whether the melt flowed through a

constant or a divergent channel.

1.1 THE FLOW PATTERN METHOD POINTED THE WAY FORWARD

Even 20 years ago, injection moulders and mould builders were already

confronted with the same problems as today, namely: where should the gates be

located, how many gates should there be, and where can weld lines or even entrapped

air occur. At that time, the so-called flow pattern method had been developed by the IKV

Plastics Processing Institute of the Technical University of Aachen, which made it

possible to simulate cavity filling with a compass and pencil on the basis of a developed

view of the moulded part. Once the flow pattern had been compiled, the developed view

was cut out and glued to give the 3D moulded part. A new flow pattern had to be

compiled for each new gate position and this was naturally very time consuming.

Working on from this, a joint research project was set up with industry under the

name CADMOULD with the aim of developing a calculation model for use in the

rheological, thermal, and mechanical layout of an injection mOUld. Those involved in the

project were raw materials producers, machine producers, injection moulders and

producers of standard mould components. At the same time, MOLDFLOW in Australia

also developed a system for theological simulation. These inltial programs simply

produced tables showing the prevailing pressure losses, viscosITies, shear rates and

temperatures, by way of a result. This nonetheless marked the start of computer-aided

simulation for injection mOUlding. [9]

Figures 1.0 : Flow pattern method

Simulation of mould filling through a developed view of the moulded part, diagram

of wheel lining

Midway through the 1980s, computers were able to calculate flow pattems.

Following this, the pace of development of simulation programs increased, and it was

soon possible to calculate not only the filling phase, but also the holding pressure phase,

as well as the fibber orientation, shrinkage, and warpage.

The product design study shall be strongly focused on the viabilrty,

competitiveness and marketability of the product itself. Unlike any other investigations

that are involved in survey analysis, this study suggests innovative products that are

based mainly on function, features and material to be used.

The product that has been selected is an injection-moulded part. In fact, the tasf;

of designing such parts can be extremely difficult due to the complexities of both the part

geometry and the moulding process. It is also difficult for experienced designers to work

with new plastic material grades that require many processes and perform in a different

manner than those materials previously used.

Injection moulding is the most important plastics processing process for

engineering & precision parts. The process are considered as a complex process as it

involved a lot of variables such as polymer material, complexities of part design, type oi

the moulds and processing condition set on the machine. Time for tool development and

manufacturing are extremely important in this industry. [10]

The development of the tool and the product has to be fast without neglecting

their quality. Quality, consistency of the process and cost of the part playa major role in

this industry. By adapting what is known as concurrent engineering such as

incorporating Plastics CAE / Simulation from the early conceptual design stage it can

optimise the result. Computer aided engineering (CAE) is the process of using a

computer and appropriate software to assist in the design and engineering of

components.

The benefrts of using CAE software to design and engineer components include:

improved and consistent component quality. Lower costs associated with the need for

less prototyping, rework and lower product development cycle time. Improved produC1

design before the commencement of manufacturing lower manufacturing cycle times.

[12]

For plastics CAE technology to be widely used in industry, it should provide that it

have an acceptable balance of the time, effort, resources used in preparing and running

the analysis and most important a reasonably accurate simulation result. Currently, there

are two methods used for the plastics CAE or simulation of shell type's plastics structure.

This thesis paper attempts to find best material, best locating gate and type of mould can

be used in the project. The pre-processing work involved from obtaining the CAD data

until completing is also discussed.

4

CHAPTER II

2.0 LITERATURE REVIEW

We have agreed to dIvide the tasks according to our discussion. My tasks focus

more on Moldftow analysis. The idea is to design and development new product so that

the detail design can be thoroughly tested before we prepare to manufacturing. A idea

new product calls for a feasibility study, not only about whether or not it is possible to

realize a product, but also to identify structural and material problems, liability and

safety issues well ahead of time so that all surprises are eliminated. Rather, the

identification of problems becomes a part of the product planning.

2.1 CABLE TIES HISTORY

The need to collect, contain and control multiple wires into tightly organized

bundles appeared with the invention of the first products that contained electrical wiring

systems. Electrical wiring had to be bundled and routed within the equipment to

prevent or reduce damage to wiring, isolate wires from moving parts and to provide

consistent, organized and efficient wiring layouts to facilitate tracing and servicing of

internal wiring systems. [1)

5

2.2 THE FIRST CABLE TIE

The first device that was used to bundle and route wires effectively were similar

in appearance and function to today's standard cable tie. It had a steel pawl or barb

inserted at an angle inside its head. Although this design provided fine adjustment and

self-locking it required two separate, time consuming manufacturing operations -

moulding the tie and insertion of the steel pawl. In addition, there was the possibility

that the steel pawl could work loose or break off, with potentially disastrous resutts if it

fell into printed circuits or closely spaced relay contacts. [1]

The next major development was a two-component, self-locking cable tie

completely produced from nylon material. Atthough it was finely adjustable, it still

maintained the time-consuming, two-step manufacturing process. Because of its

design, this improved cable tie provided better hand-eye coordination and reduced

installation time. Over time cable tie design improved steadily and eventually led to the

development of a one-piece moulded self-locking nylon cable tie. [1]

2.3 MODERN CABLE TIE

Since the development of the first one-piece, self-locking cable tie its design

was steadily refined to improve the effectiveness of the product as a wire bundling

device. The basic one-piece, self-locking cable tie now comes in many sizes and styles

for a diverse range of applications. It has also been modified into specialty ties with all

the qualities of the basic tie, plus added features for different uses. [1)

6

2.4 CABLE TIE CHARACTERISTICS

A cable tie is a band or length of strap manufactured from a class of polymeric

materials known as polyamides (Nylon 6/6). The width, length and head area employ

ratcheting mechanisms to bundle and then lock items together. Commercially

introduced in 1938, nylon was the first synthetic semi-crystalline polymer whose

physical properties compared favourably to some metals. Nylon possesses an

outstanding balance of properties, combining strength, moderate stiffness. high service

temperature and a high level of toughness. Particularly resistant to repeated impact.

nylon has a low coefficient of friction and excellent abrasion resistance. It is resistant to

fuels, lubricants, and most chemicals, but is attacked by phenols, strong acids and

oxidizing agents. Nylon is inherently susceptible to environmental conditions. However.

many cable ties are moisturized to attain optimum performance levels. Nylon products

should be stored in a cool, dry area, out of direct sunlight, and sealed in the original

packaging material to extend performance levels indefinitely.

2.5 THREE TYPES OF NYLON FOR SPECIFiC APPLICATIONS

2.5.1 General-purpose nylon is suitable for most applications at a continuous

temperature up to 1500 F. Nylon 6/6, the grade most often used for cable ties. meets

UL 94V-2 flammability ratings. Its working temperature range is 400 F. to 1850 F.

2.5.2 Heat Stabilized Nylon 6/6 is used for applications with continuous or extended

exposure to high temperatures, up to 2500 F., and thereby meeting UL standards for

electrical applications. HST cable ties contain specially-formulated heat stabilizers to

provide additional thermal endurance.

2.5.6 UV Stabilized Nylon 6/6 is used in applications of continuous or extended

exposure to outdoor elements. The weather-resistant grade. able to endure additional

7

ultraviolet (UV) light, is produced by incorporating stabilizers in the nylon resin. HST's

UV Stabilized Nylon cable ties are available only in black. [6]

2.6 THE NEED FOR PLASTIC·FLOW ANALYSIS

The field of flow analysis has gained increasing importance in injection

moulding. Flow analysis has provided rational solution to many of the hard-to

understand effect that cause problem in the moulding process. These effects have

included warping, moulded-in stress, excessive fill pressure, part flashing and other.

The interrelationship between part design and moulding process parameters that

cause problems of this nature were not well understood in the industry.

Practical experience often was insufficient to identify potential problem and too

kneed to have encountered the full range of moulding problem that can be address by

techniques such as flow analysis. Hence, much prototyping and mould fine-tuning were

necessary before successful moulded product could be achieved.

Computerized flow analysis has emerged as a powerful tool to aid in the

implementation of applying injection moulding as the production process of choice to

widening spectrum of products. The ability of modem digital computer to perform

complex calculation in short periods of time has been the breakthrough that makes

flow analysis a tool applicable to increasing number of new parts.

Computer simulation of the injection moulding process is not new. In fact,

virtually since the introduction of the computer attempts have been made to develop

simulations. However, according to basic flow laws, the flow rate into each section or

element must equal the flow rate out each section. This gives a boundary condition Mat

allows the flow pattem to be calculated. The divided flow method has proved very

successful in practice, enabling a wide range of complex parts to be analysed. The

mould is first divided into number of flow paths, then each flO\N path broken into

sections. This modelling has to be done manually, usually by the mould designer.

Some skill is required to recognize the various flow paths and to be able to align the

section in the direction of flow. [12)

8

2.7 ADVANTAGES OF FLOW ANALYSIS

There are multitudes of factor that must be considered when creating a plastics

part or mould design. Key influence such as component geometry, wall thickness, the

number and position of the gates, material choice, shrinkage allowances and mould

design are all interrelated. Part and mould design cannot be based purely on form and

function but must also consider the effect of manufacturing. [2]

The CAE simulation provides engineers, designers, moulders with a visual and

numerical feedback about what actually happens inside the mould cavity during the

injection moulding process.

2.7.1 ADVANTAGES TO PRODUCT DESIGNER

Product designer will always be concerned if the part that he produced can be

injected or will the part fin at all especially with the larger injection moulded component.

The relationships among material structural properties, cosmetic properties and

processing properties are generally hazy in the designer mind, and flow analySis

provides a way to evaluate different materials in the design stage and the processing

related characteristic in a scientific manner.

What will be the part wall thickness was another primary consideration for the

cost of the moulded product. The ability to thin wall on the product result in obvious

saving in material (comprises 40% of finish product cost). By assigning thin wall

thickness indirectly it will reduce the cycle time of the moulded part. This will increase

productivity of the moulded plant and it will reflect the cost of the product. [3]

The ability of plastic materials to be form into attractive styled has long been

recognized. This has led to an increasing use of plastic materials for application

requiring high degree of aesthetical appeal. Proper use of flow analysis tool can help

assure product designer that sufficient latitude exists in the design to allow gates to be

position to protect the aesthetic properties of the design, while at the same time

allowing production of the item at reasonable cost.

9

2.7.2 ADVANTAGES TO MOULD DESIGf\lERlMOULDMAKERS

Good fill pattern is very important in any injection moulded component. A good

fill pattern for a moulding is one that is unidirectional and consistent molecular

orientation in the moulded product. Flow analysis helps to avoid warpage problem

caused by differential orientation, an effect that is the best demonstrated by warpage

that occurs in thin centre gated disks. [3]

In order to achieve a controlled fill pattem, the mould designer must select the

number and location of gates that will result in the desire pattem. Flow analysis can

help by allowing the designer to try multiple of gate location and evaluate the impact on

the moulding process.

Normally the balance runner systems are certainly desirable but it may lead to

problem in mould cooling or increase the cost due to excessive runner-tOopart weight.

By using flow analysis it allow the best designs of runner to balance for pressure,

temperature, or combination of both. They also allow an evaluation of the shear rate

and degree of frictional heating that will be produced in the runner system, which can

avoid the problem of material degradation or excessive mett temperature variation

delivered to the mould cavity. [3J

One of the major benefits of the flow analysis is the increased probability that

the mould run successfully the first time in the trial. This will save lot of time and money.

2.7.3 ADVANTAGES TO INJECTION MOULDER

Flow analysis can provided an objective view of the impact of changes of

primary injection moulding process parameter such as melt temperature, mould

temperature, injection speed and injection pressure.

Optimisations of the process parameter allows the moulder to produce parts

with minimal levels of residual stress, which can result in post moulding warpage or

even mechanical failure of the product. [3]