GRADUATION THESIS FINAL

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

SCHOOL OF MATERIALS SCIENCE AND ENGINEERING ------o0o------

GRADUATION THESIS

Student: Vu Dinh Thang

Class: Materials Science Engineering, Advanced Program

Student ID: 20113349

Course: K56

Advisor: Assoc. Prof. Le Thai Hung

Hanoi, 2016

Vũ

Đìn

h T

hắn

g

R

esea

rch,

des

ign

, fa

bri

cate

ele

ctr

ical

so

cket

co

ver

by

usi

ng

SM

C m

ater

ials

2

01

4, Ju

ne

HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY

SCHOOL OF MATERIALS SCIENCE AND ENGINEERING ------o0o------

GRADUATION THESIS

“RESEARCH, DESIGN AND FABRICATE ELECTRICAL

SOCKET COVERS BY USING POLYMER MATRIX

COMPOSITE WITH GLASS FIBER REINFORCEMENT

(SMC)”

Student: Vu Dinh Thang

Class: Materials Science Engineering, Advanced Program


Course: K56

Advisor: Assoc. Prof. Le Thai Hung

Hanoi, 2016

MINISTRY OF EDUCATION AND TRAINING

HANOI UNIVERSITY OF SCIENCE AND

TECHNOLOGY

.................................................

SOCIALISTS REPUBLIC OF VIETNAM

Independence – Freedom – Happiness

…………………........

Student‟s name: Vu Dinh Thang


Course: K56

Major: Materials Science Engineering

1. Topic

Research, design, fabricate electrical socket covers by using polymer matrix

composite with glass fiber reinforcement (SMC)

Initial data:

Sheet molding compound materials

Graduation thesis “research about rheological behavior of SMC materials” of

Nguyen Quy Dat – student at School of Materials Science and Technology

2. Content:

Theoretical overview

Design electrical socket cover mold

Simulate compression process

Experimental fabricate electrical socket covers

Test and analyze mechanical, thermal and electrical properties of the products.

Advisor‟s signature

Hanoi University of Science and Technology Graduation thesis

Vu Dinh Thang, MSE-K56 Page 4

CONTENTS

LIST OF FIGURES ........................................................................................................... 6

LIST OF TABLES ............................................................................................................. 8

ABSTRACT ....................................................................................................................... 9

ACKNOWLEDGMENT ................................................................................................. 10

CHAPTER 1: THEORETICAL OVERVIEW ............................................................. 11

1.1 Overview of the research process ........................................................................ 11

1.1.1 Research purposes ......................................................................................... 11

1.1.2 Research methodology and approach ........................................................... 11

1.2 Definition and classification of composite materials ........................................... 11

1.2.1 Definition of composite materials ................................................................. 11

1.2.2 Properties of composite materials ................................................................. 12

1.2.3 Classification of composite materials ........................................................... 12

1.3 Overview of polymer matrix composite .............................................................. 14

1.3.1 Definition ...................................................................................................... 14

1.3.2 Properties ....................................................................................................... 15

1.3.3 Classification ................................................................................................. 15

1.4 Overview of SMC composite materials ............................................................... 15

1.4.1 Definition of SMC composite materials ....................................................... 15

1.4.2 Matrix polymer of SMC composite materials ............................................... 15

1.4.3 Reinforcement ............................................................................................... 17

1.4.4 Properties of SMC materials ......................................................................... 18

1.5 Fabricating SMC materials .................................................................................. 20

1.6 Applications of SMC materials ............................................................................ 23

1.7 History and current research about SMC materials ............................................. 24

1.8 Summary .............................................................................................................. 27

CHAPTER 2: DESIGNING THE MOLD AND SIMULATING COMPRESSION

PROCESS ......................................................................................................................... 28

2.1 Overview about compression molding ................................................................ 28

2.2 Technical demands of a compression mold ......................................................... 29



2.3 Mold manufacturing process................................................................................ 29

2.4 Designing on Solidworks software ...................................................................... 29

2.4.1 Introduction of Solidworks software ............................................................. 29

2.4.2 Mold designing steps ..................................................................................... 30

2.5 Introduction of Deform 3D software ................................................................... 32

2.6 Technical specifications and simulation process ................................................. 32

2.6.1 Simulation steps ............................................................................................ 32

2.6.2 Behavior model of fabricated sheet molding composite ............................... 38

2.6.3 Boundary conditions ..................................................................................... 39

2.6.4 Simulation results .......................................................................................... 40

2.7 Summary .............................................................................................................. 41

CHAPTER 3: FABRICATING ELECTRICAL SOCKET COVER ......................... 42

3.1 Manufacturing the electrical socket cover mold .................................................. 42

3.2 Introduction about equipment .............................................................................. 43

3.3 Material demands of the compression process .................................................... 45

3.4 Technical modes of the compression process ...................................................... 46

3.5 Fabricating electrical socket cover process ......................................................... 50

3.6 Summary .............................................................................................................. 52

CHAPTER 4: TESTING AND ANALYZING PROPERTIES OF ELECTRICAL

SOCKET COVER ........................................................................................................... 53

4.1 Testing mechanical, thermal and electrical properties methods .......................... 53

4.1.1 Testing compressive strength method ........................................................... 53

4.1.2 Testing flexural modulus method.................................................................. 53

4.1.3 Measuring thermal resistance method ........................................................... 54

4.1.4 Measuring breakdown voltage ...................................................................... 55

4.1.5 Measuring surface resistor ............................................................................ 55

4.2 Mechanical, thermal, electrical properties of the socket products ....................... 56

CONCLUSIONS .............................................................................................................. 60

REFERENCES ................................................................................................................ 61

APPENDIX....................................................................................................................... 62



1 LIST OF FIGURES

Figure 1.1: The classification of composite materials based on reinforcement phase ...... 13

Figure 1.2: The classification of composite materials based on matrix phase .................. 14

Figure 1.3: A representative unsaturated (ortho) polyester resin ...................................... 16

Figure 1.4: Oversimplified scheme of a typical compounding line (paste mixing + SMC

machine). ........................................................................................................................... 20

Figure 1.5: Photograph showing chopped glass fiber bundles falling onto the lower paste

film ..................................................................................................................................... 22

Figure 1.6: Applications of SMC composite materials ..................................................... 24

Figure 1.7: Assumption of composite materials in the world ........................................... 25

Figure 1.8: Assumption of composite materials in Vietnam ............................................. 25

Figure 2.1: Compression mold of sheet molding composite materials ............................. 28

Figure 2.2: A Solidworks drawing of electrical socket cover ........................................... 30

Figure 2.3: An electrical socket covert. ............................................................................. 30

Figure 2.4: A 3D model of the socket cover mold. ........................................................... 31

Figure 2.5a: a model 3D of bottom mold .......................................................................... 31

Figure 2.5 b: a model 3D of top mold. .............................................................................. 31

Figure 2.6: A model of complete mold ............................................................................. 32

Figure 2.7: Import Geometry command ............................................................................ 34

Figure 2.8: Insert a behavior model of material ................................................................ 35

Figure 2.9: Mesh for work piece ....................................................................................... 35

Figure 2.10: Movement command .................................................................................... 36

Figure 2.11: Set up temperature ........................................................................................ 36

Figure 2.12: Set up friction coefficient.............................................................................. 37

Figure 2.13: Set up steps for simulation problem ............................................................. 37

Figure 2.14: Database generation command ..................................................................... 38

Figure 2.15: Simulation results .......................................................................................... 38

Figure 2.16: Stress- strain curve of fabricated SMC materials. ........................................ 39

Figure 3.1 (a): A top die of electrical socket cover mold .................................................. 42



Figure 3.1(b): A bottom die of electrical socket cover mold ............................................ 42

Figure 3.2: Hydraulic vertical press .................................................................................. 43

Figure 3.3: System of mold heating .................................................................................. 43

Figure 3.4: Rod resistors .................................................................................................... 44

Figure 3.5: Thermocouples ................................................................................................ 44

Figure 3.6: Thermal resistant plates .................................................................................. 45

Figure 3.7 (a): Grease ........................................................................................................ 45

Figure 3.7 (b): Silicone release agent ................................................................................ 45

Figure 3.8: The second compression result ....................................................................... 47

Figure 3.9: the third compression result ............................................................................ 48

Figure 3.10: The fouth compression result ........................................................................ 49

Figure 3.11: The fifth compression result ......................................................................... 49

Figure 4.1: MTS 809 axial/ torsional testing machine 100kN .......................................... 53

Figure 4.2: Three points bending flexural test .................................................................. 54

Figure 4.3: Thermometer machine US 450 ....................................................................... 55

Figure 4.4: high voltage one direction testing machine model Phenix 4100-10. .............. 55

Figure 4.5: Surface resistor measuring machine ............................................................... 56

Figure 4.6: Stress- strain curve of an socket cover product. ............................................. 57



LIST OF TABLES

Table 1.1: Typical properties of different glass fibers ..................................................... 18

Table 1.2: Typical properties of SMC ............................................................................... 20

Table 2.1: Boundary conditions of simulation problem .................................................... 40

Table 2.2: Simulation results of three boundary conditions .............................................. 41

Table 3.1: the compositions of SMC material ................................................................... 46

Table 3.2: Technical modes of compression process ........................................................ 46

Table 4.1: Flexural strength of the products ...................................................................... 57

Table 4.2: Compression strength of the products .............................................................. 58

Table 4.3: Thermal resistance, break down voltage and surface resistor of the products . 58

Table 4.4: Comparison some properties between manufactured products and standard

properties of SMC materials .............................................................................................. 59



ABSTRACT

In recent years, science and technology in the world is growing greatly, especially in

the study of new materials because of their wide applications in many fields of life. The

highlight is introduction and development of polymer composite materials. Polymer

composite materials have many advanced properties as well as applied widely in real life

such as light, stability, wear resistance, long life cycle, and etc. With many progressive

properties, they will gradually replace traditional materials like steel, iron, wood in all of

our life. Despite this, in Vietnam, polymer composite materials still remain relatively

extraneous to domestic industries because of a shortage in science and technology.

One of the most recently popular polymer composite types is sheet molding

composite material (SMC). The sheet molding composite materials (SMC) is a thermoset

polymer matrix composite, and is usually fabricated by hot compression molding method.

Graduation thesis: “research, design and fabricate electrical socket cover by using

polymer matrix composite with glass fiber reinforcement (SMC)” will contribute to the

research and development of sheet molding composite in Vietnam. This research will

focus on process of fabricating composite materials SMC as well as manufacturing a

practical application of SMC in electrical industry – electrical socket cover. Besides, the

mechanical, thermal and electrical properties of products are evaluated and investigated in

order to satisfy technical requirements in the electrical industry.

Keywords: Sheet molding compounds (SMC), polymer matrix composite, and glass

fiber, electrical socket cover.



ACKNOWLEDGMENT

This project would not have been possible without the support of many people. I

would like to express my gratitude to my professors at School of Materials Science and

Engineering, Hanoi University of Science and Technology, my advisors Associate

Professor Dr. Le Thai Hung for their support and supervision in orienting studies at

HUST and conducting this research.

Particular thanks go Associate Professor Dr. Le Thai Hung for his valuable

comments and helpful advice, scientific guidance and electrical socket cover valuable

feedback throughout the time at HUST, especially with my work.

I would also like to extend my appreciation and gratitude to the Laboratory of

Mechanical Testing Properties and National Key Laboratory for Polymer and Composite

Materials for helping me to carry on some experiments in their laboratories.

Finally, I wish to express my special thanks to my family for their great

encouragement throughout my project and thesis, as well as my friends for their continual

support and encouragement.

Hanoi, June 2016

Student

Vu Dinh Thang



CHAPTER 1

THEORETICAL OVERVIEW

1.1 Overview of the research process

1.1.1 Research purposes

Manufacturing successfully electrical socket cover made from sheet molding

composite materials.

Investigating mechanical properties of sheet molding composite materials in order

to satisfy the demands of manufacturing these products.

Applying simulation tools such as Solidworks, Deform3D to fabricate electrical

socket cover.

Testing mechanical, electrical properties of socket cover products.

1.1.2 Research methodology and approach

1.1.2.1 Research methodology

This research is based on combination of theoretical basics with deformation

simulation process and experimental methodology.

- Theoretical basics about materials: based on the mechanical, chemical

properties of sheet molding composite materials.

- Simulating compression molding process of electrical socket cover on Deform

3D software and then determining the technological parameters and molding

specifications.

- Practical methodology: manufacturing electrical socket cover and testing

mechanical properties of these products.

1.1.2.2 Research content

- Design and manufacture a compression mold to produce electrical socket cover.

- Simulate the mold filling of products by using Deform3D software.

- Manufacture electrical socket cover in a compression mold

- Test and analyze mechanical, electrical and thermal properties of products which is

manufactured; and compared to practical demands.

1.2 Definition and classification of composite materials

1.2.1 Definition of composite materials

Many of our modern technologies require materials with unusual combinations of

properties that cannot be met by the conventional metal alloys, ceramics, and polymeric



materials. This is especially true for materials that are needed for aerospace, underwater,

and transportation applications. For example, recently, aerospace engineers are

increasingly searching for new advanced materials that have low densities, are strong,

impact resistant, and are not easily corroded. Frequently, strong materials are relatively

dense; also, increasing the strength or stiffness generally results in a decrease in impact

strength.

Material property combinations and ranges have been, and are yet being, extended

by the development of composite materials. Generally speaking, composite materials are

combination of two or more constituent materials with significantly distinct properties in

order to produce new materials with aggregate performance exceeding that of its

components.

1.2.2 Properties of composite materials

The technological and commercial interest in composite materials derives from the

fact that their properties are not just different from their components but are often far

superior. Some of the possibilities include:

Composites can be designed that are very strong and stiff, yet very light in weight,

giving them strength to-weight and stiffness-to-weight ratios several times greater than

steel or aluminum. These properties are highly desirable in applications ranging from

commercial aircraft to sports equipment.

Fatigue properties and toughness are generally better than for the common

engineering metals. Furthermore, composites can be designed that do not corrode like

steel in order to apply in maritime industries.

With composite materials, it is possible to achieve combinations of properties not

attainable with metals, ceramics, or polymers alone.

Better appearance and control of surface smoothness are possible with certain

composite materials.

1.2.3 Classification of composite materials

Many composite materials are usually composed of just two phases; one term is the

matrix, which is continuous and surrounded the other phase, often called the

reinforcement because it usually serves to strengthen the composite. The properties of

composites are a function of the properties of the constituent phases, their relative

amounts, and the geometry of the reinforcement phase. The reinforcing phase may be in

the form of fibers, particles, or various other geometries. The phases are generally

insoluble in each other, but strong adhesion must exist at their interface(s). The effective

method to increase the strength and to improve overall properties is to incorporate



dispersed phases into the matrix, which can be an engineering material such as ceramic,

metal or polymer.

The matrix in a composite is the continuous phase providing uniform load

distribution to the reinforcing constituent(s). The matrix material serves several functions

in the composite. First, it provides the bulk form of the part or product made of the

composite material. Second, it holds the imbedded phase in place, usually enclosing and

often concealing it. Third, when a load is applied, the matrix shares the load with the

secondary phase, in some cases deforming so that the stress is essentially born by the

reinforcing agent.

The reinforcing phase may be in the form of fibers, particles, or various other

geometries. The phases are generally insoluble in each other, but strong adhesion must

exist at their interface(s). The effective method to increase the strength and to improve

overall properties is to incorporate dispersed phases into the matrix, which can be an

engineering material such as ceramic, metal or polymer.

Figure 1.1: The classification of composite materials based on reinforcement

phase

Another way to distinguish the composite materials is based on matrix phase below:

Metal Matrix Composites (MMCs) include mixtures of ceramics and metals,

such as cemented carbides and other cermet, as well as aluminum or

magnesium reinforced by strong, high stiffness fibers.



Ceramic Matrix Composites (CMCs) are the least common category.

Aluminum oxide and silicon carbide are materials that can be imbedded with

fibers for improved properties, especially in high temperature applications

Polymer Matrix Composites (PMCs). Thermosetting resins are the most widely

used polymers in PMCs. Epoxy and polyester are commonly mixed with fiber

reinforcement, and phenol is mixed with powders. Thermoplastic molding

compounds are often reinforced, usually with powders

Figure 1.2: The classification of composite materials based on matrix phase

1.3 Overview of polymer matrix composite

1.3.1 Definition

Polymer matrix composites (PMCs) are comprised of a variety of short or

continuous fibers bound together by an organic polymer matrix. Unlike a ceramic matrix

composite (CMC), in which the reinforcement is used primarily to improve the fracture

toughness, the reinforcement in a PMC provides high strength and stiffness. The PMC is

designed so that the mechanical loads to which the structure is subjected in service are

supported by the reinforcement. The function of the matrix is to bond the fibers together

and to transfer loads between them.



1.3.2 Properties

Polymer matrix composite is a class of composite materials, so it inherits many

advanced properties of composite materials. Besides, the advantages of PMCs are their

light weight coupled with high stiffness and strength along the direction of the

reinforcement. This combination is the basis of their usefulness in aircraft, automobiles,

and other moving structures. Other desirable properties include superior corrosion and

fatigue resistance compared to metals. Because the matrix decomposes at high

temperatures, however, current PMCs are limited to service temperatures below about

600° F (316° C).

1.3.3 Classification

A simple classification of polymer matrix composite is based on matrix phase, which

is given in Figure 1.2; the three classes: thermosets, thermoplastics and rubbers.

Thermosets: are composite whose resins react and harden either at room

temperature or on heating because the polymer of thermoset composite is

usually heavily cross-linked.

Thermoplastics: In thermoplastic composites, the individual molecules of

polymer are linear in structure with no chemical linking between them. They

are held in place by weak secondary bond such as van der Walls. Therefore,

these composites may be repeatedly heated, fabricated and cooled and

consequently scrap may be recycled.

Rubbers: the individual molecules of polymer are linear in structure, and there

is linking between them. They cannot be repeatedly heated or fabricated.

This study investigates the SMC composite materials which belong to thermosets

class.

1.4 Overview of SMC composite materials

1.4.1 Definition of SMC composite materials

Sheet molding compounds (SMC) are fiber-reinforced thermosetting semi-finished

products. They are produced in thin uncured and thickened sheets between 1 and 3 mm

thick that can be handled easily.

1.4.2 Matrix polymer of SMC composite materials

The matrix in a composite is the continuous phase providing uniform load

distribution to the reinforcing constituent(s). The matrix, in addition to protecting the

reinforcing constituent(s), safeguards the composite surface against abrasion, mechanical

damage and environmental corrosion.



In this research, the matrix of SMC composite material is made of unsaturated

polyester, catalysts and accelerators, fillers, thickeners and additives.

Unsaturated polyesters are the most versatile class of thermosetting polymers.

They are macromolecules consisting of an unsaturated component, (i.e., maleic

anhydride or its transisomer, fumaric acid; which provides the sites for further

reaction), and a saturated dibasic acid or anhydride with dihydric alcohols or

oxides (typically phthalic anhydride, which can be replaced by an aliphatic acid,

like adipic acid, for improved flexibility). If blends of phthalic anhydride and

maleic anhydride/fumaric acid are used, „ortho resins‟ (Figure 1.3) are produced.

Figure 1.3: A representative unsaturated (ortho) polyester resin

In most cases, the polymer (polyester) is dissolved in a reactive vinyl monomer,

i.e., styrene, to give a proper solution viscosity. The resin is cured by use of a free

radical catalyst, the decomposition rate of which determines the curing time.

Hence, curing time can be decreased by increasing the temperature (for a high

temperature cure, say at 100 ºC, benzoyl peroxide is commonly used; whereas for a

room temperature cure, other peroxides with metal salt accelerators are preferred).

Crosslinking reactions occur between the unsaturated polymer and the unsaturated

monomer, converting the low viscosity solution into a three-dimensional network

system. Crosslink densities can change (by direct proportionality), the modulus, Tg

and thermal stabilities; and (by inverse proportionality), strain to failure and impact



energies. The formation of the cross-link structure is accompanied by some volume

contraction (7%–27%).

Catalysts and accelerators: For polyester-type resins, peroxides are the main

catalysts. Common examples are benzoyl peroxide (BPO) and t-butyl perbenzoate,

which is a high temperature catalyst.

Fillers are used in SMC as low cost inert additives. In addition, fillers can:

o modify the viscosity and act as flow control agents

o reduce the CTE (coefficient of thermal expansion)

o serve as heat sink for exothermal that develop during the curing reaction

o increase hardness, rigidity and dimensional stability.

The most common powder filler is calcium carbonate. Ground clay (kaolin clay) is

also used; however it causes more discoloration and higher shrinkage than calcium

carbonate. Talc is often used for improved electrical strength and resistance to

humidity. Aluminum hydrate is commonly used for fire retardancy as it contains

35% of hydration water, which is released upon exposure to fire. Powdered

polyethylene is used in low profile (low shrinkage) formulations, since it improves

surface quality and impact strength. Antimony trioxide and chlorinated waxes are

also used for self-extinguishing properties.

Thickeners: To ensure controlled moldability, thickeners are used for controlled

increase of the viscosity of the polyester resin. Typical thickeners are magnesium

oxide and hydroxide, calcium oxides and hydroxides.

Miscellaneous additives: In addition to the additives mentioned in the previous

section, stearates are used for internal mold release and as various pigments for

coloring.

1.4.3 Reinforcement

Chopped E glass type fibbers are used as the reinforcing agent.

Glass fiber is simply a composite consisting of glass fibers, either continuous or

discontinuous, contained within a polymer matrix; this type of composite is produced in

the largest quantities. The composition of the glass that is most commonly drawn into

fibers (sometimes referred to as E-glass) is contained 55% wt of SiO2, 16% wt of CaO,

15% wt of Al2O3, 10% wt of B2O3, and 4% wt of MgO; fiber diameters normally range

between 3 and 20 µm.

Glass is an amorphous material composed of a silica network. There are four main

classes of glass used commercially: high alkali (essentially soda-lime-silica: A glass),

electrical grade (a calcium aluminous-borosilicate with low alkali oxide content: E glass),

chemically-resistant modified E glass grade (with calcium aluminous-silicate: ECR glass)



and high strength grade (with magnesium aluminous-silicate and no boron oxide: S glass).

Fibers from any of these can be prepared, however, E glass fiber is the one most widely

used for reinforcement purposes, although S glass fiber has the highest tensile strength

and elastic modulus of these four types of glasses (Table 1.1).

Glass fiber is spun from the melt and it is obtained after cooling it to the rigid

condition without crystallizing. Once the continuous glass fibers are produced, they are

transformed into one of the finished forms, which are (continuous or woven) roving,

yarns (mostly for textile applications), chopped strands, (glass fiber) mats and pre-forms.

Table 1.1: Typical properties of different glass fibers

Material Density,

kg/

Tensile

Strength,

MPa

Young's

Modulus,

GPa

CTE,

/K

Strain to

Failure, %

E-Glass 2620 3450 81 5.0 4.9

S-Glass 2500 4590 89 5.6 5.7

A-Glass 2500 3050 69 8.6 5.0

Glass is popular as a fiber reinforcement material for several reasons:

It is easily drawn into high-strength fibers from the molten state

It is readily available and may be fabricated into a glass-reinforced plastic

economically using a wide variety of composite-manufacturing techniques.

As a fiber it is relatively strong, and when embedded in a plastic matrix, it

produces a composite having a very high specific strength.

When coupled with the various plastics, it possesses a chemical inertness that

renders the composite useful in a variety of corrosive environments.

The surface characteristics of glass fibers are extremely important because even

minute surface flaws can deleteriously affect the tensile properties. Surface flaws are

easily introduced by rubbing or abrading the surface with another hard material. Also,

glass surfaces that have been exposed to the normal atmosphere for even short time

periods generally have a weakened surface layer that interferes with bonding to the

matrix. Newly drawn fibers are normally coated during drawing with a size, a thin layer

of a substance that protects the fiber surface from damage and undesirable environmental

interactions. This size is ordinarily removed prior to composite fabrication and replaced

with a coupling agent or finish that produces a chemical bond between the fiber and

matrix.

1.4.4 Properties of SMC materials

SMC are versatile materials: their formulation can be adjusted and tailored to meet

the requirements of a diverse range of applications. Compression molding of SMC allows



processing complex and large shapes on a rapid cycle time. Features such as inserts, ribs,

bosses, and attachments can be molded in. This process needs little mold preparation and

generates few scraps, thus reducing the cost of trimming operations. Good surface

finishes are obtainable, contributing to lower part-finishing cost. This process can also be

automated.

Compared, for instance, to steels, SMC provide design freedom and flexibility by

accommodating shape complexity and geometric details; reduced manufacturing

complexity through part integration in a single assembly; and combining structural,

assembly, and integration functions (e.g., antennae embedment); substantial weight

reduction (∼20–35% lighter than equivalent steel parts); superior corrosion resistance;

and reduced tooling costs (40% less than tools for steel stamping). SMC also offer

enhanced damage resistance from dents and dings, especially in exterior cladding (body

panels), as compared to aluminum alloys and steels; good harshness properties; and good

noise and vibration properties. The benefits of using SMC are also: in-mold coloring and

powder priming for painted parts with the requirement of high temperature resistance

from 150 to 2000C for e-coat application.

Compared with injection molded parts, particularly those produced using the BMC

process; SMC parts have better mechanical properties. For instance, equivalent parts

exhibit typically an average thickness of 2.5 mm in the SMC case, whereas this thickness

is about 3.5 mm in the case of injection molded BMC to meet the same mechanical

requirements. This is due to the highest length of the fibers used in SMC. Even if fibers

having the same length can be used in both processes, it is known that injection processes

have a clear tendency to damage the fibrous reinforcement resulting in a drastic length

reduction. This shows a limitation and inefficiency in the injection processes. On the

contrary, compression molding allows a lower freedom of design and complex geometry

to be molded. This can be seen as an advantage when comparing SMC with prepreg

fabrics: the latter indeed offer higher mechanical properties, but the parts have simpler

geometry.

For many applications, SMC compete with fiber-reinforced thermoplastic materials.

Those materials can be injection molded or compression molded as GMT. SMC parts

have better mechanical properties, heat resistance, better than usual dimensional stability

and environmental resistance, and cost-effective thermoplastic composite parts. In

contrast, fiber-reinforced thermoplastics generate fewer scraps than SMC, thus lowering

labor costs. Furthermore, SMC have some disadvantages: the continuous thickening of

the paste, the variations of the rheological properties, as well as the emission of styrene,

which impacts the curing reaction, the variations of the basis weight, and the cooling of

molding parts, which may induce some geometrical distortions if not controlled properly,



still remain tricky to control at the industrial scale. But there is no clear trend yet that

SMC will be replaced by composite thermoplastics. Indeed, assembly can be

manufactured from a subset of parts. SMC can be used for the structural parts of the

assembly, whereas visible skins can be composed of thermoplastic composites. This type

of solution is currently implemented in the automotive industry. Nevertheless, painted

SMC body panels are still being produced without major insoluble industrial problems.

Various formulations yield a spectrum of physical and mechanical properties of the

final products.

Table 1.2: Typical properties of SMC

General Purpose High Toughness Low Shrink

Specific gravity 1.14 1.17 1.67

Flex modulus, GPa 4.2 3.9 11.6

Flex strength, MPa 95 150 85

Tensile strength, MPa 70 76 35

Tensile elongation, % 1.8 4.0 -

Barcol hardness 50 45 60

1.5 Fabricating SMC materials

According to a research about sheet molding composite on Dat‟s graduation thesis

[10] and a paper of LAURENT ORGEAS [4], the fabricating process of SMC material is

showed below.

A production line of the most-used SMC, that is, with UP resins, is generally

composed of three units: the paste-mixing unit, the SMC machine, where the fibrous

reinforcement is chopped (in case of continuous fibers or fiber bundles) and paste-

impregnated to form the sheets, and the maturation unit, where the thickening of the paste

is ensured. The first two units are schematized in Fig. 1.4.

Figure 1.4: Oversimplified scheme of a typical compounding line (paste

mixing + SMC machine).



Paste Mixing

In order to minimize possible sources of variability of the paste formulation, a

continuously controlled process is adopted to manufacture the uncured SMC paste.

Usually (Fig. 14), the paste is prepared by using at least two distinct mixing

reservoirs, which are continuously fed with correct proportions of raw materials.

One of them

(e.g., reservoir B) contains a precise dosage of the thickening agents, apart from

the resin, which is put in the other one (e.g., reservoir A). When sufficiently

blended, the resulting batches are then in-line combined to form a complex non-

Newtonian paste (with a steady-state shear viscosity of ≈10–100 Pa s) that is next

carried toward the SMC machine. At this stage, the thickening of the paste is

initiated. Notice that because of the mixing process, the paste may have some

residual voids [14]. Furthermore, it is of great importance that the paste

constituents are homogeneously blended in order to limit subsequent paste

properties gradients in the produced sheets.

SMC Machine:

As shown in the scheme given in Fig. 1.4, the uncured and unthickened paste is

applied from the two doctor boxes (equipped with doctor blades) of the SMC

machine onto a lower and an upper, continuous, impermeable and moving carrier

films (e.g., polyethylene, films). The quantity and the thickness of deposited paste

along the width (≈0.5–2 m) of the carrier films can be tuned from the doctor

blades, the paste-feeding rate, and the velocity of the carrier films along the

machining direction. A dry fibrous bed is then formed by letting the discontinuous

fibers or fiber bundles fall onto the lower carrier film, as illustrated in Fig. 1.5.

Such a fiber placement is central and has to be achieved cautiously, because it

primarily contributes to the future architecture of the fibrous reinforcement inside

the undeformed sheets. Any inappropriate fiber placement will produce

heterogeneous dry fibrous mats, then sheets, followed by unwanted heterogeneous

flows during compression molding and finally undesirable properties of produced

SMC parts. Hence, the fiber placement must produce the most homogeneous dry

fibrous bed, with prescribed and controlled fiber grammage and fibrous

microstructure all along the lower carrier film. The microstructure and the height

of the resulting dry fibrous bed (fiber content, orientation, and connectivity)

strongly depend both on the processing conditions, such as the carrier film

velocity, the reinforcement feeding rate, its height fall, the quality of the chopping

(in case of initial continuous fibrous reinforcement, see below), and on the fiber

properties, such as the fiber sizing (which can affect tribological properties of

fibers), the fiber or fiber bundle geometry, and so on. Figure 1.4 illustrates how



such a fiber placement is achieved in the case of initially continuous fiber bundles.

In this situation, roving rollers feed a chopper with a prescribed network of parallel

and continuous fiber bundles. The chopper, which mainly controls the uniformity

of the fibrous reinforcement, is, for example, made up of two steel cylinders, that

is, a first one with an elastomer skin, and a second one that is equipped with razor

blades (Fig. 1.5). Continuous fiber bundles, which are forced to pass between the

two cylinders, are severely bent locally by the blades that compress the bundles

and the elastomer and then break. The distance between neighboring blades

controls the length of chopped bundles. The geometrical and physical properties of

the bundles, and in particular their sizing (antistatic agents), contribute to the

quality of the chopping. Thereafter, the dry fibrous mat is sandwiched between the

two resin-rich carrier films, and the whole stack „„lower film + paste + fibrous mat

+ paste + upper film‟‟ is progressively squeezed by crossing a series of calendering

cylinders to finally produce the sheets (Fig. 1.4). To optimize the sheet forming,

that is, the compression of the dry fibrous reinforcement and its impregnation by

the paste, the calendering rolls usually display spline profiles that depend on the

considered roll.

Figure 1.5: Photograph showing chopped glass fiber bundles falling onto the

lower paste film

SMC Maturation



After the SMC machine, the produced and collected sheets are often packed by a

thin polymer film (e.g., cellophane). This film limits the loss of styrene before the

end of thickening and compression molding, whereas the PE carrier films also

protect the produced sheets from humidity. These two types of protection films,

together with the strict preconditioning of the raw materials guarantee, in case of

metal oxides or hydroxides thickening agents, the best maturation conditions and

conservation of thickened SMC. Furthermore, to ensure optimal thickening,

packed sheets are stored in a dedicated maturation area, where the temperature

(nominal value ranging between 20 and 30C) together with the relative humidity

(nominal value ranging between 20% and 50% HR) are accurately controlled.

Under such maturation conditions, the thickening of the paste is properly achieved

until the paste viscosity reaches a forming plateau (cf. Fig. 7). Beyond this

maturation time, the SMC can be preserved (in colder rooms) and used for

compression molding for several weeks or months (depending on the paste

formulation)

1.6 Applications of SMC materials

Today, SMC materials are used worldwide and represent a major part of the world‟s

thermoset composites. Globally, the compression molding of SMC is the third most

intensively used technique for the production of polymer composite parts worldwide

(behind the injection of reinforced thermoplastics and the hand lay-up techniques). It

represents about 15% of the total of produced parts and of the total of materials used by

the composite industry. There is a large diversity of fields of applications for SMC. The

automotive and truck industries remain the drivers of the SMC technology, but SMC are

commonly used in the agricultural, rail and marine (interior and body parts, watercraft

parts, etc.), electrical (low voltage and medium voltage energy systems, fuses and

switchgear, cabinets and junction boxes, encapsulation of wirings and electronic circuits,

electrical components with reduced surface resistivity, lamp housings) and energy (parts

for wind turbine and solar power applications, etc.), sanitary (sinks and bath tubs, toilet

seats, drain covers, etc.), domestic appliance (blower housings, drain pans, and heating,

ventilation, and air conditioning (HVAC) systems, vent trims, parabolic mirrors,

swimming pool panels, etc.), building and construction (drinking water tanks, panels,

doors, etc.), and medical (surgery equipment, dental medication systems, antibacterial

components) sectors.

In the automotive and truck industries, SMC parts are used notably in exterior and

interior body panels, painted (class A parts) and unpainted, semi-structural and structural

parts. Basically, class A means that the surface finish has to exhibit an aspect of flatness,

smoothness, and light reflection similar to that of stamped steels. A non-exhaustive list of



automotive parts gives, for instance, bumpers, fenders, trunk divider, hood and door

assemblies, deck lids, body panels, fenders, roof panels, spoilers, step assists, back panels,

wheelhouses, firewalls, grilles, tailboards, cargo lids, stowage tubs, headlamp housings,

and supports. More recently, high temperature under-hood parts have been developed

(e.g., valve covers).

SMC composite materials are widely used to produce assemble parts in short time

curing. Typical applications include demanding electrical applications, corrosion resistant

needs, structural components at low cost, automotive, and transit. SMC delivers high

surface quality. SMC is used for larger parts where higher mechanical strength is needed.

Figure 1.6: Applications of SMC composite materials

1.7 History and current research about SMC materials

In the today industrialized trend of my country, the composite products are used

more and more widely, at the same time the quality requirements for these products are

also enhanced. The below pie charts shows that consumption and applicant fields of

composite materials in the word and in Vietnam (Figure 1.7, 1.8). This requires that

people must seize control of modern technology, of which the two main requirements are

high productivity and stable quality. Therefore, being along with researches about



fabricating composite materials, studies on manufacturing technology of product are

essential necessary.

Figure 1.7: Assumption of composite materials in the world

Figure 1.8: Assumption of composite materials in Vietnam

One of the most effective applications is polymer matrix composite. This material

has many advantages and is used widely not only in industries but also in other areas of

life, thanks to simple manufacturing process and small investment. One of the prominent

braches of the polymer matrix composite is sheet molding composite material (SMC). In

this thesis, I focus on studying about SMC material.

Sheet molding composite material is a form of thermoset polymer matrix composite

material. Compared to metal materials, SMC materials have many advantages as higher

fatigue strength, higher corrosion resistance and lower weight [1, 2]. With the rapid

development of science and technology, the demands for improved performance of these

structural materials as well as producing environmental friendly materials such as



composites made from soy, jute and pineapple are become necessary [3]. Therefore, many

companies and researchers spend a lot of attention to develop this material. In 2012,

LAURENT ORGEAS and his partners had indicated overview about SMC material,

fabricating process and rheology of this material in paper “sheet molding composite” [4].

Tiesong et al studied the effect of fiber content on mechanical properties and fracture

behavior of short carbon fiber reinforced geo-polymeric matrix composites with different

volume fractions [5]. Furthermore, some researchers were interested in investigating the

influence of temperature, pressure and other additive on polymer matrix composite

compression molding process. For example, Kenny and Opalicki concerned the curing

stage by focusing on the influence of the type of granular and fibrous fillers and other

additives [6]. Millischer and Delaunay studied about the influence of the temperature and

confining pressure [7]. Laurent Orgéas and Thai-Hung Le investigated the influence of

lubricate on compression molding of BMC materials [8]. However, up to now, there is a

few researches related to rheology of SMC in the mold filling state. The compression

molding experiments with colored SMC shows that the combination of vacuum assistance

and high mold temperatures should be avoided especially in moldings where undesired

weld lines are expected, since the combination tends to enlarge the weld line [9]. In a

graduation thesis about rheological behavior of sheet molding composite, Nguyen Quy

Dat showed a rheological model of the material in order to explain the rheology of it [10].

Generally, most of most of these researches focus on investigating these influences as

well as mechanical properties of a specific polymer matrix, but they didn‟t indicate a

specific standard applicant process of SMC material in real life.

In Vietnam, these materials are recently interested about a period of 10 years ago.

Some studies also initially approach and research about polymer matrix composites such

as successfully fabricating polymer matrix composite reinforced by glass and bamboo

fibers [11]. Professors of Hanoi University of Science and Technology had initial results

of studying about SMC material manufacturing technology [12]. It can be noticed that the

awareness of the importance of researches on composite materials technology in our

country have improved significantly. Besides, because of the need for a material that can

replace concrete in order to apply in harsh environmental conditions, scientists has

researched successful a steel polymer composite reinforced by glass fiber; this product is

applied in many constructions in Vietnam. However, these researches are based mostly on

experience as well as being only applied in laboratory scale. This limits the improvement

of the quality as well as organization of industrial production of composite products in our

country. According to recent statistical results, most of raw materials to produce SMC

composite in our country are imported mainly from China, Korea and Japan with high

price. Therefore, successful researches and manufacture of SMC composite materials are

essential because of its abundant applications in industries especially in electrical and



automotive industry. Furthermore, researches on the electrical field of manufacturing

polymer matrix composite materials are now mainly focus to fabricate with phenolic

resin. The main disadvantage of this polymer is the longer time of compression process as

well as higher temperature than SMC materials. Also, electrical parts are manufactured by

thermoplastic materials with low cost, but its thermal resistant ability is so low. Moreover,

working life of this material is rapidly declined in outdoor environments. Besides, in

previous research, we have successfully fabricated circuit breaker products by using bulk

molding composite materials [15]. This research will focus on using simulation software

in order to test accuracy of the electrical cover mold as well as indicating a standard

process to manufacture socket cover product.

1.8 Summary

Through this chapter, we can see that SMC materials are used widely in electrical

and automotive industries thanks to its advanced properties such as light, high corrosion.

However, while most of domestic researches are only focused on fabricating SMC

materials and properties of SMC, there are a few researches studying on standard

procedure to apply SMC materials in electrical industry. Therefore, this thesis researches

on using SMC material to manufacture electrical socket cover and investigates

mechanical, thermal and electrical properties of the product.



CHAPTER 2

2 DESIGNING THE MOLD AND SIMULATING

COMPRESSION PROCESS

2.1 Overview about compression molding

Compression molding is a molding method in which the molding material, generally

preheated, is first placed in an open, heated mold cavity. The mold is closed with a top

force or plug member, pressure is applied to force the material into contact with all mold

areas, while heat and pressure are maintained until the molding material has cured. The

process employs thermosetting resins in a partially cured stage, either in the form of

granules, putty-like masses, or preforms.

Materials may be loaded into the mold either in the form of pellets or sheet, or the

mold may be loaded from a plasticizing extruder. Materials are heated above their melting

points, formed and cooled. The more evenly the feed material is distributed over the mold

surface, the less flow orientation occurs during the compression stage.

Compression molding is a high-volume, high-pressure method suitable for molding

complex, high-strength glass fiber reinforcements. Advanced composite thermoplastics

can also be compression molded with unidirectional tapes, woven fabrics, randomly

oriented fiber mat or chopped strand. The advantage of compression molding is its ability

to mold large, fairly intricate parts. Also, it is one of the lowest cost molding methods

compared with other methods such as transfer molding and injection molding; moreover it

wastes relatively little material, giving it an advantage when working with expensive

compounds.

An example of the compression molding is showed in figure 2.1.

Figure 2.1: Compression mold of sheet molding composite materials



In order to product electrical socket cover, a compression mold is applied in this

research.

2.2 Technical demands of a compression mold

Parts or products, which are manufactured by compression molding method, is

demanded to have correct size as well as satisfy technical requirements of product

drawing.

The mold should be designed to manipulate easily.

The working and exposure surfaces of the mold must ensure the glossy and

smoothness in order to decrease the friction and the adhesion of SMC materials

onto the mold.

Components of the mold should be undergone heat treatment so that ensure

toughness of the mold. Besides, we should choose appropriate material for each

component of the mold.

2.3 Mold manufacturing process

The compression mold of socket cover is manufactured by the following steps:

2.4 Designing on Solidworks software

2.4.1 Introduction of Solidworks software

Solidworks is a solid modeling computer-aided design (CAD) and computer-aided

engineering (CAE) computer program that run on Microsoft Windows. Solidworks

utilizes a parametric feature-based approach to create models and assemblies. Parameters

refer to constraints whose values determine the shape or geometry of the model or

assembly. Parameters can be either numeric parameters, such as line lengths or circle

1

• Design a compression mold based on a socket cover product.

2 • Use Deform 3D software to run simulation problem for

the mold in order to test the mold.

3 • Manufacture the mold base on technical drawings.



diameters, or geometric parameters, such as tangent, parallel, concentric, horizontal or

vertical, etc. Design intent is how the creator of the part wants it to respond to changes

and updates. Features refer to the building blocks of the part. They are the shapes and

operations that construct the part.

Solidworks software is applied broadly in mechanical design, construction and

architecture… in order to create details or products with complex shape and surface that

the other software cannot design. Therefore, Solidworks is the most suitable software to

design and manufacture a compression mold.

2.4.2 Mold designing steps

The electrical socket cover mold is designed by following steps:

A drawing of socket cover model is based sizes and shapes of the original one

with 95mm in length, 60mm in width, and 28mm in height (in figure 2.3).

We use Solidworks software to draw this model by using sketch (2D) and

features (3D) toolbars. (Figure 2.2)

Figure 2.2: A Solidworks drawing of electrical socket cover

Figure 2.3: An electrical socket covert.



By using some toolbars in Solidworks such as parting line, shut-off surface,

tooling split, the model of the socket cover mold in 3-dimensions is created in

Solidworks. (Figure 2.4)

Figure 2.4: A 3D model of the socket cover mold.

By using tool split toolbar, we create model of top mold and bottom mold of

the mold. (Figure 2.5)

(a) (b)

Figure 2.5a: a model 3D of bottom mold

Figure 2.5 b: a model 3D of top mold.

Based on specifications of the socket cover product and the compress which

is used to compress, we can design other details of the mold. After that, we

start to assemble them with top die and bottom die in order to create a

complete mold. (Figure 2.6). A drawing of mold and the other details are

showed in Appendix.



Figure 2.6: A model of complete mold

After the mold is designed successfully on Solidwork software, we began to

simulating compressive process of this mold on Deform 3D software, which is showed in

the below section, in order to testing accuracy and fulfill probability of the mold.

2.5 Introduction of Deform 3D software

Simulation is one of the most important parts in manufacturing process. Thanks to

many useful tools of simulation software, we can change technical parameters or

boundary conditions in order to find out the most optimal manufacturing technique.

Moreover, instead of using a lot of time or money to actual test and analyzing, now we

can achieve these results only by simulation, thereby improving productivity. With the

development of science and technology, a growing number of simulation soft wares have

been created so as to engineers and designers can work more efficiently, one of which is

Deform 3D software.

DEFORM™-3D is a powerful process simulation system designed to analyze the

three-dimensional (3D) flow of complex metal forming processes. DEFORM-3D is a

practical and efficient tool to predict the material flow in industrial forming operations

without the cost and delay of shop trials. Typical applications include: closed die forging

– open die forging –machining – rolling – extrusion – heading – drawing – cogging

– compaction – upsetting .

2.6 Technical specifications and simulation process

2.6.1 Simulation steps



The simulation is done on deform 3D software with some basic following steps.

Create geometry model of

product

Build a behavior model of

material

Mesh for a work piece

Set up boundary

conditions: temperature,

friction,…

Run simulation

Analyze

results

True

End

False



1. Creating geometry model of electrical socket cover:

We designed the geometries model of electrical socket cover in Solidworks

software and then use command “import geometry” to import these geometries

into deform3D software.

Figure 2.7: Import Geometry command

2. Building a behavior model of material:

In this step, we set up material for the work piece by using command “general”,

“Object type – plastic” and import the behavior model of material to library of

Deform 3D software. The behavior model is created base on stress- strain graph of

sheet molding composite while the statistic of stress and strain is calculated from

actual compression experiments. Besides, we should suppose that material of top

and bottom die is rigid.



Figure 2.8: Insert a behavior model of material

3. Meshing for the work piece:

In this step, the work piece is divided into small particles with finite number. The

number of particles greatly affect to the accuracy of the simulation problem. The

more work piece is meshed, the higher accuracy is achieved. In contrast, if the

numbers of particles are too large, the time for simulation process will last a lot.

Therefore, depending on the purpose of the simulation problem, we can choose the

number of particles which is meshed so that not only achieve the desired results

but also save time. Based on experience and purpose of simulation problem, the

elements, which are meshed about 50000, are the most suitable.

Figure 2.9: Mesh for work piece



4. Setting up boundary conditions:

Firstly, we decide the movement of top die by using command “movement”. In

this problem, the direction of the top die‟s movement is +Z. Besides, work piece

and bottom die need to be fixed.

Figure 2.10: Movement command

Secondly, we set up temperature by using commend “general – temperature”. We

suppose that the temperature is constant during compression process.

Figure 2.11: Set up temperature

Thirdly, we use command “Inter-object” to adjust the friction coefficient between

dies and work piece.



Figure 2.12: Set up friction coefficient

Fourthly, we go to Simulation Controls in order to set up steps of top die. In this

case, the step is -1 and the time is until the top die meets the bottom die.

Figure 2.13: Set up steps for simulation problem

Finally, we check all above step by using command “database generation”



Figure 2.14: Database generation command

5. Running simulation:

After simulating, we get simulation results below:

Figure 2.15: Simulation results

6. Analyzing results:

In the final step, we investigate simulation results of the mold such as the filling

quality of the mold and shape of the product.

2.6.2 Behavior model of fabricated sheet molding composite

According to the reference [4] and [10], the SMC is a viscosity plastic material.

Hence, in this research, the behavior model of material is used as visco- plasticity.

σ = (ε, ε‟, T)

Where: σ is stress

ε is strain

ε‟ is strain rate

T is temperature.



This behavior model shows that the function of stress depends on strain, strain rate

and temperature, especially properties of the materials. In this research, the model

is an actual curve of stress and strain which is calculated by compression

experiments of sheet molding composite materials (Figure 2.16). This curve is

built at strain rate 0.01, and ratio fiber and matrix of SMC material about 28%-

72%, according to Dat‟s graduation thesis [10].

Figure 2.16: Stress- strain curve of fabricated SMC materials.

2.6.3 Boundary conditions

The boundary conditions of simulation problem are created by the practical working

conditions of SMC materials. In the simulation process, while parameters of the boundary

condition is changed, simulation results are compared to each other in order to indicate

the most suitable condition to manufacture successfully products which have the best

quality. The boundary conditions are showed below.

The distance between top die and bottom die: h= 30mm

The distance has to be large enough to ensure the safety of compression process

and easily take the product out of the mold. However, it cannot be so large that

save time and money in the process. Based on experience and calculating, we

identified that the distance about 30mm is the most suitable.

Velocity of mold: v= 1-2 (mm/s)

The velocity from 1 to 2mm/s is suitable because of the following reasons. If the

top die moves with high velocity, it has a bad effect on the filling of material as

well as can make some defects such as fracture, porous, so the product quality will

become poor. In contrast, if the top die moves with low velocity, not only may the



productivity be negatively affected, but the material can also solidify before the

mold is filled completely.

Compression temperature of the mold: T= 120-160

Based on calculations about solidified temperature in the previous research “Dat‟s

graduation thesis” the working temperature of SMC materials is varied from 120 to

160

Friction coefficient : f = 0.5-0.7

Because the SMC material is applied at temperature from 120 to 180 , and

friction between the mold and materials is sliding friction, the friction coefficient

of simulation process is fluctuated from 0.5 to 0.7.

In the simulation problem, we decided to survey three cases of the boundary

conditions

Table 2.1: Boundary conditions of simulation problem

Boundary condition

1

Boundary condition

2

Boundary

condition 3

Temperature ( ) 120-130 150-160 150-160

Velocity of mold (mm/s) 2 1 1

Friction coefficient 0.5 0.5 0.5

2.6.4 Simulation results



Table 2.2: Simulation results of three boundary conditions

Boundary condition 1 Boundary condition 2 Boundary condition 3

Results: the product doesn‟t

have the full desired shape,

SMC material cannot be

fulfilled the mold

Results: the product has full

shape, but surfaces of

product are not smooth.

Results: the product has

desired shape, and surface

quality is good

Reasons: It may cause the

low temperature, so the

rheology of material is quite

bad.

Reasons: It may cause the

high velocity of the mold.

Because the high velocity

leads to the fulfill property

of material

Base on the simulation results, we indicated the best boundary condition for compression

process as well as testing accuracy and fulfill quality of the manufactured mold.

2.7 Summary

Base on the simulation results, we tested the mold and concluded that the mold is

completely met requirements to produce electrical socket cover. Besides, we indicated the

best boundary condition for compression process (see below).

The distance between top die and bottom die: h= 30mm

Velocity of mold: 1mm/s

Compression temperature of the mold: 150-160

Friction coefficient: 0.5



3 CHAPTER 3

FABRICATING ELECTRICAL SOCKET COVER

3.1 Manufacturing the electrical socket cover mold

After testing the accuracy and fulfilling capacity of the mold by Deform 3D, we

started to manufacturing the mold based on the 2D technical drawings. (Figure 3.1)

Figure 3.1 (a): A top die of electrical socket cover mold

Figure 3.1(b): A bottom die of electrical socket cover mold



3.2 Introduction about equipment

Hydraulic vertical press (Figure 3.2)

Figure 3.2: Hydraulic vertical press

The system of mold heating:

The system is made up of three circuit breakers and two electrical temperature

controllers. Figure 3.3

Figure 3.3: System of mold heating

Rod resistors:



Figure 3.4: Rod resistors

The mold is heated by six rod resistors with dimension Ф12 x 150mm. These

resistors are fitted to heated holes in the mold.

Thermocouples:

Thermocouple is a kind of thermometer consisting of two wires of different

metals that are joined at both ends; one junction is at the temperature to be

measured and the other is held at a fixed lower temperature. (Figure 3.5)

Figure 3.5: Thermocouples

Thermal resistant plates:

In order to decrease heat loss and reduce productivity in compression process,

we use two thermal resistance plates. (Figure 3.6)



Figure 3.6: Thermal resistant plates

Lubricating materials:

(a) (b)

Figure 3.7 (a): Grease

Figure 3.7 (b): Silicone release agent

3.3 Material demands of the compression process

SMC material must be prepared according to standard procedure, which is described

in chapter 1. Besides, the materials should be stored carefully to avoid contacting with

environment as well as being solidified before applying to fabricate electrical socket

cover. The table below shows compositions of the SMC material.



Table 3.1: the compositions of SMC material

Compositions of the material Proportion

Unsaturated polyester polymer 20-23%

E-glass fiber with 25mm length, 14µm

diameter

18-28%

Styrene 1.8-2%

Zinc stearate 1.1-1.3%

Calcium carbonate 32-35%

Impact-resistant plastic PS 14-16%

Benzoyl peroxide 0.1%

3.4 Technical modes of the compression process

Generally speaking, the compressing experimental process is one the most important

process in the processes of manufacturing electrical socket cover. The experimental

process aims to investigate quality of the mold as well as checking shape of fabricated

products in order to ensure technical requirements.

After installing completely the mold onto the hydraulic press, we begin to

compressing experimentally electrical products. Noticeably, the experimental process was

conducted many times to find out the most suitable mode of compression process and

provide standard fabrication process. The experimental compressions are given below.

Table 3.2: Technical modes of compression process

1st time Entered SMC material mass: 130(g)

Temperature: 150

Pressure in the mold: 130 N/

Compression time: 10 minutes

2nd

time Entered SMC material mass: 130(g)

Temperature: 150



3rd


Temperature: 150



Taper of the mold is increased

4th


Temperature: 150





5th


Temperature: 150



The mold is coated by chromium

The first time:

Base on calculating mass of electrical sample and properties of sheet molding

compound materials, we set up technical parameters for compression process:

mass of materials is 130(g), temperature is about 150 ; pressure is 130 N/ ,

and compression time is 10 minutes.

- Results: the mold cannot be opened, and product is stuck in the mold.

- Reasons: The material may not have enough time to transform to solid form,

so it stuck in the mold. According calculating and simulating on Deform 3D

software, the material is solidified in 10 minutes at temperature 150 .

However, in the compression process, heat must to transfer from the mold

to the material, so the material may take some time to reach 150 , and the

compression time about 10 minutes is not enough.

- Fixing methods: Firstly, the mold is dismounted off the press, and defective

product is taken out of the mold. Secondly, the compression time is

increased to 12 minutes in the following compression.

The second time:

In the second compression, the compression time is about 12 minutes and the other

parameters are remained unchanged.

- Results: the product cannot be taken out because the material remains stuck

in the mold

Figure 3.8: The second compression result



- Reasons: lubricated process may not be fulfilled carefully and the taper

of the mold is not enough, leads to material stuck in the mold.

- Fixing methods: Firstly, we take the adhesive materials out of the mold,

and noticeably prevent damage for surfaces of the mold. After that, the

taper of the mold is increased and the mold must be lubricated carefully

to ensure that product is taken out easier.

The third time:

Being different from the second time, in this time the taper of mold is increased

and the mold is lubricated carefully.

- Results: Product is taken successfully out of the mold; however, the

product has not fulfilled completely its shape yet.

Figure 3.9: the third compression result

- Reasons: The material may be lacked, leads to the shape of product

being not fulfilled completely. According theoretical calculating of

sample model, the mass of material is about 130(g), but during

compression process the material may undergo plastic shrinkage, results

in the lack of product shape.

- Fixing methods: After conducting some compressions, the material,

needed to fabricated process, is about 150(g)

The fourth time:

In this time, the mass of material is increased to 150(g); the other parameters are

remained unchanged.

- Results: Products is compressed and taken out easily, but their surfaces

are not good, and smooth.



- Reasons: The surface of mold may not polish and coated, so it affects

quality of product shapes. Besides, the pressure in the mold may not

enough, so it leads to surface of product become blister.

- Fixing methods: The mold is coated with chromium, and the pressure in

the mold is increased to 150 N/

Figure 3.10: The fouth compression result

The fifth time:

In this time, the pressure in the mold was gone up to 150 N/ , the other

parameters are remained unchanged.

- Results: the compression process run smoothly and products have good

shapes and ensure quality of products

Figure 3.11: The fifth compression result

Finally, we indicated the standard technical mode for fabricating electrical socket

cover process:



- Entered SMC material mass: 150(g)

- Temperature: 150

- Pressure in the mold: 150 N/

- Compression time: 12 minutes

3.5 Fabricating electrical socket cover process

Derived from the above technical modes, this thesis proposes the standard procedure

to manufacturing electrical socket cover in the below diagram.

Prepare mold such as cleaning,

lubricating.

Mount the mold on the presses

Heat the mold

Prepare sheet molding composite

materials

Manufacture electrical socket cover

Take products out of the mold

Testing mechanical, thermal, electrical

properties and analyze products



1. Preparing the mold for compression process:

The mold preparing process contains two main stages: cleaning the mold and

lubricating the mold by grease and release agents.

Cleaning the mold: In this stage, we apply a layer of oil onto the surface of

the mold, and then use fine grindstone to polish the mold surface in order to

avoid dirt or crack on the mold which can create defects of the products,

before use a tower to clean the oil layer on the mold.

Lubricating the mold: In this stage, we use a tower which is applied a layer

of grease to polish working surfaces of the mold, and then spray silicone

release agent to the mold so that products won‟t be adhesive to the mold after

compressing.

2. Mounting the mold onto press:

The pressing process is done on one direction- vertical hydraulic press. Firstly, the

mold is put onto a thermal resistant plate which lies on surface of the press by

using crane. Noticeably, the mold should be located in the center of the press.

Secondly, the bottom of the mold is fixed on below table of the press by mold

insert tools, before put the second thermal resistant plate on the top one. Thirdly,

we adjust the press to lift the mold until it contacts to the above table, then fix the

top die on this table. Finally, we control press to open and close the mold in order

to ensure that the top die and bottom die are matched.

3. Heating the mold:

The heating process is divided into two stages: mount the heating system to the

mold and heat the mold.

In the first stage, we put six rod resistors into heating holes, which are

drilled on the mold, before connect them to electrical power of heating

system by using electrical bonding and insulation tape. Then, we connect

the thermocouples of heating system to the mold, while connecting the

heating system to electrical power. Noticeably, we should use electrical

tester pen to ensure safety.

In the second stage, we turn on the electrical power and set up temperature

of heating system to heat up the mold. The most suitable temperature is

about 150-160 . Noticeably, we should monitor the heating process

carefully to avoid heat loss.

4. Prepare sheet molding composite materials:

The SMC material is fabricated before, in this step, the materials should be

prepared during heating mold time. We weight the materials by electronic balance

to ensure the accuracy of mass. The necessary mass of SMC materials is about

150g. Noticeably, the materials should be kept in a plastic bag to avoid contact



with environment in order to eliminate chemical reactions of the material and

environment or dirt, etc.

5. Manufacture electrical socket cover :

When the temperature reaches 150-160 , we start to manufacture electrical socket

cover. Firstly, we control the press to split the mold (the distance between two dies

should be about 30cm to easily put material to the mold). Secondly, after spraying

silicone release agent to the mold, we put the prepared material into the mold,

before closing the mold. We should use insulation gloves to press the material into

the mold so that it can be filled all cavity of the mold. Thirdly, we close the mold

with slow velocity and then set up pressure for the compression machine. In order

to ensure surface quality as well as the filling of the mold, the pressure should be

about 150 kg/ . The compression time should range from 12 to 15 minutes.

Noticeably, temperature and insulation of the mold should be usually checked in

order to ensure safety.

6. Take products out of the mold:

The process of obtaining product is achieved by using pushing system which is

designed on the mold. Firstly, when the below table of the press is gone down

slowly, the mold will be open and the pushing system will gradually push product

out of the mold. After that, we use gloves to take product out of the mold, then

clean and spray silicone release agents to the mold in order to prepare for the next

compression. Finally, we use a file to eliminate excess of the product as well as

perforate holes for product.

7. Testing mechanical, thermal and electrical properties and analyze products:

In this step, the mechanical, thermal and electrical properties of the product such as

tensile strength, fatigue strength are tested in the laboratory by using the MTS 809

axial/ torsional testing machine or measuring surface resistors machine, etc.

Besides, we also analyze the product quality such as investigating surface quality,

shape and filling of product, etc.

3.6 Summary

In this chapter, the thesis indicated the complete socket cover mold and five

technical modes of experimental compressive process in order to determine the most

suitable mode to manufacture electrical socket cover. Furthermore, based on the standard

procedure, we have manufactured successfully electrical socket cover and in the next

chapter they will be tested mechanical, thermal and electrical properties.



CHAPTER 4

4 TESTING AND ANALYZING PROPERTIES OF

ELECTRICAL SOCKET COVER

4.1 Testing mechanical, thermal and electrical properties methods

4.1.1 Testing compressive strength method

The compressive strength is calculated following ISO standard 527-1993, on the

machine MTS 793- 100kN with the compressive velocity about 5mm/minutes,

temperature 25 , humidity being smaller than 70%.

Figure 4.1: MTS 809 axial/ torsional testing machine 100kN

The compressive strength of products is calculated by below equation:

Where: - : is compressive strength, (MPa)

- F is force, (N)

- a is the current length of the product (mm)

- b is the current width of the product (mm)

4.1.2 Testing flexural modulus method

The flexural modulus is calculated according the three points bending flexural test at

condition: velocity 5mm/minutes, temperature 25 , humidity being smaller than 70%, on

MTS 793- 100kN.



Figure 4.2: Three points bending flexural test

The flexural modulus is calculated by below equation:

Where: is flexural Modulus of elasticity,(MPa)

L is support span (mm)

b is width of test beam (mm)

d is thickness of tested beam (mm)

m is gradient of the initial straight-line portion of the load deflection curve

4.1.3 Measuring thermal resistance method

This test is performed on thermometer machine US 450.



Figure 4.3: Thermometer machine US 450

Technical parameters:

- Maximum temperature: Tmax= 1500 0C

- Size of machine : 170x290x170 (mm)

- Electrical power: 380V/50Hz.

- Power capacity: 13kW

4.1.4 Measuring breakdown voltage

The breakdown voltage is measured by high voltage one direction testing machine

model Phenix 4100-10.

Figure 4.4: high voltage one direction testing machine model Phenix 4100-

10.


- Input: 220V-5V, 50/60 Hz

- Output: 0-100 k VDC, 0-10 mA

- Machine accuracy: 0.5% FS

- Measuring voltage range: 0-100 kV

- Measuring current range: 0- 19.99 mA

4.1.5 Measuring surface resistor

The surface resistor of the product is measured by surface resistor measuring

machine ADVANTEST.




- Measurement of Micro Current from 10 fA to 19.999 mA

- Measurement of High Resistance from 10 to 3 1016

- High-Speed Charge/Discharge

- High-Speed Measurement with 100 Samples/Second

- Floating Measurement of 1100 VDC

Figure 4.5: Surface resistor measuring machine

4.2 Mechanical, thermal, electrical properties of the socket products

Figure 4.6 shows the relation between force and displacement of an electrical socket

cover product in a flexural test. According to this figure, the behavior of the socket is

nonlinear elastic deformation, which is totally suitable to the behavior of standard SMC

materials and the maximum force, which can applied, is approximately 1.30 (kN) at

displacement 1.86 (mm).



Figure 4.6: Stress- strain curve of an socket cover product.

The below tables are showed compressive strength, flexural strength of the products.

Table 4.1: Flexural strength of the products

Sample Size of the sample Maximum force

(kN)

Flexural

modulus

(GPa) Length

(mm)

Width

(mm)

Height

(mm)

1 95 60 28 1.22 22.3

2 95 60 28 1.15 21.4

3 95 60 28 1.18 21.5

4 95 60 28 1.22 22.0

5 95 60 28 1.15 22.4

6 95 60 28 1.15 21.5

7 95 60 28 1.20 22.0

8 95 60 28 1.30 23.0

9 95 60 28 1.18 21.5

10 95 60 28 1.27 22.8

Average 1.20 22.04



Table 4.2: Compression strength of the products

Sample Size of the sample Maximum

force

(kN)

Displacement

(mm)

Flexural

modulus

(GPa) Length

(mm)

Width

(mm)

Height

(mm)

1 95 60 28 52.2 70 22.3

2 95 60 28 54.7 70 21.4

3 95 60 28 54 70 21.5

4 95 60 28 56.8 70 22.0

5 95 60 28 56.5 70 22.4

6 95 60 28 57.6 70 21.5

7 95 60 28 55 70 22.0

8 95 60 28 54.7 70 23.0

9 95 60 28 55.8 70 21.5

10 95 60 28 55.4 70 22.8

Average 55.3 70 22.04

The table 4.3 indicated thermal resistance; break down voltage and surface resistor

of the products.

Table 4.3: Thermal resistance, break down voltage and surface resistor of the

products

Sample Thermal resistance( ) Breakdown voltage (kV) Surface resistor (Ω)

1 180 > 30 kV 2.4

2 180 > 30 kV 3.0

3 180 > 30 kV 3.2

4 180 > 30 kV 2.4

5 180 > 30 kV 4.5

6 180 > 30 kV 3.2

7 180 > 30 kV 1.8

8 180 > 30 kV 4.3

9 180 > 30 kV 3.4

Average 180 > 30 kV 2.4

Table 4.1 shows that maximum compressive strength of the products is varied from

145 to 160 MPa, while the flexural modulus is changed from 21.4 to 22.8 GPa, that is

indicated in table 4.2. In addition, table 4.3 shows that the maximum thermal resistance is

180 ; while the breakdown voltage is greater than 30kV and the surface resistor is varied

from 1.8 to 4.3 . These prove that the products have relatively good

mechanical properties as well as might completely apply in electrical industry, especially

in high voltage environment.



After testing some mechanical, thermal and electrical properties of socket cover

products, we compared them with standard properties of sheet molding composite in the

world, according to reference [3].

Table 4.4: Comparison some properties between manufactured products and

standard properties of SMC materials

Properties of SMC Units Properties of products Standard properties

Compressive strength MPa 153.6 151-220

Flexural modulus GPa 22.04 15-25

Thermal resistance 180 190-200

Surface resistor Ω 2.4 1012-1013

As we can see in the table 4.4, most of the mechanical and electrical properties of

products, such as compressive strength, flexural modulus, surface resistor, is in the range

of standard properties of SMC materials. All of these prove that the manufactured

products completely meet technical requirements and can be applied in the electrical

industry.



CONCLUSIONS

Based on the testing mechanical, thermal and electrical results of socket cover

products, we can conclude that:

Manufactured the complete mold of electrical socket cover as well as fabricating

electrical socket cover.

After testing properties of products, we concluded that the manufactured sockets are

totally met technical requirements in order to apply in electrical industry.

Indicated successful fabrication process of electrical socket cover as well as applied in

electrical industry.



REFERENCES

[1] M.M. Schwartz,Composite Materials: Properties, Nondestructive Testing and Repair,

V.1, Prentice- Hall Inc., New Jersey, USA, 1997.

[2] A.A. Baker, P.J. Callus, S. Georgiadis, P.J. Falzon, S.E. Dutton and K.H. Leong, An

affordable methodology for replacing metallic aircraft panels with advanced composites,

Composites: Part A, 33(2002), 687–696.

[3] http://www.bulkmolding.com/

[4] SHEET MOLDING COMPOUNDS, LAURENT ORGEAS AND ´PIERRE J. J.

DUMONTCNRS, Grenoble Institute of Technology, Grenoble,France, 2012.

[5] Tiesong Lin, Dechang Jia, Meirong Wang, Peigang He, Defu Liang // Bull. Mater.

Sci. 32 (1) (2009) 77

[6] Kenny J, Opalicki M (1996) Processing of short fibre/thermosetting matrix

composites. Compos Part A Appl Sci Manuf 27A(3):229–240

[7] Millischer A, Delaunay D (2001) Experimental and numerical analysis of heat transfer

in bulk molding compound injection process. J Reinf Plast Compos 20: 495–512

[8] Laurent Orgéas, Thai-Hung Le// Lubricated compression of BMC, a concentrated and

fibre-reinforced granular polymer suspension

[9] Compression moulding of SMC: Coupling between the flow and the local void

contents. N.E.J. Olsson, T.S. Lundström, and K. Olofsson.

[10] Nguyen Quy Dat, graduation thesis, Hanoi University of Science and Technology,

2015.

[11] Study on fabrication of BMC laminates based on unsaturated polyester resin

reinforced by hybrid bamboo/glass fibers. Tran Vinh Dieu, Nguyen Thanh Liem, Tran

Thi Mai and Nguyen Thanh Tung. s.l. : JSMA Internaltional Journal, series A, 2004,

Vols. 47, N4, p570-573.

[12] Trần Vĩnh Diệu, Phạm Gia Huân, Science magazine, T.42. N3 (2004) 362-365.

[13] Trần Vĩnh Diệu, Phạm Gia Huân, Sience magazine, T.45, N5A (2007) 118-125

[14] Comte E, Merhi D, Michaud V, et al. Polym Compos 2006;27:289.

[15] Lê Thái Hùng, Nguyễn Kim Chính, Nguyễn Đức Thái, Vũ Đình Thắng, Nguyễn

Mạnh Hùng, Tạ Hồng Dương, Chế tạo đế chân cầu dao điện từ vật liệu compozit nền

polyme sợi thủy tinh dạng khối (BMC), Tạp chí Khoa học công nghệ kim loại, No 64,

p34-38, 2016.

http://www.bulkmolding.com/



5 APPENDIX

I. 2D drawing of top die and bottom die of the mold:



II. 2D drawing of mold details:







III. 2D drawing of the mold:

Documents

GRADUATION THESIS FINAL