DESIGN AND FABRICATION OF MINI INJECTION MOULDING

MACHINE FOR THERMOPLASTIC WASTE

ABSTRACT

Injection molding is considered to be one of the most prominent processes for

mass production of plastic components. The objective of this project is to design
and fabricate mini injection molding machine to reduce the machine cost by
developing this machine. The main reason behind this project is to reduce the
effect of plastic wastage on the environment and to increase the production rate
with low cost material. Plastic granules which are in very small size can be
easily transformed into any products using injection molding. This machine is
simpler to operate and the weight of the machine is reduced while compared
with the existing machine. The manually operated plastic injection molding
machine, it is cheaper than hydraulic and pneumatic machine. It can solve the
problem of small and medium scale industries to create small plastic
components.

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 TABLE OF CONTENTS

CHAPTER NO. CONTENT PAGE NO.

ACKNOWLEDGEMENT I

ABSTRACT II

LIST OF TABLES III

LIST OF FIGURES III

LIST OF ACRONYMS AND SYMBOLS IV

1 INTRODUCTION 1

2 LITERATURE REVIEW 2

3 MODELLING & EXPERIMENTAL SETUP 3

4 METHODOLOGY 4

5 COMPONENTS AND MATERIALS

5.1 Plastic 5

5.1.1 Types of Plastics 6

5.1.2 Characteristics 8

5.1.3 Specifications of Plastic Materials 8

5.2 Heaters 9

5.3 C-Clamp 10

5.4 Plate 10

5.5 Hollow Rods 10

5.6 Shafts 11

5.7 Nuts And Bolts 11

CHAPTER NO. CONTENT PAGE NO.

5.8 Frame 12

5.9 Paints 12

6 DESIGN,CALCULATION,WORKING MODEL
&COST ESTIMATION 13

7 MECHANISM AND FABRICATION 16

7.1 Mechanism 16

7.2 Fabrication 16

7.2.1 Marking 17

7.2.2 Cutting 17

7.2.3 Lathe Operations 17

7.2.4 Welding 18

7.2.5 Assembly 18

8 DISCUSSIONS 19

8.1 Various Problems 19

8.2 Advantages 19

8.3 Future Scope 19

9 CONCLUSION 20

10 REFERENCES 21
 LIST OF TABLES

TABLE NO TABLE NAME PAGE NO.

Thermoplastic Properties 6

Thermosetting properties 7

Specifications 12

Cost Estimation 15

LIST OF ACRONYMS AND SYMBOLS

Kg - kilogram

m3 - cubic metre

N - Newton

Kg/m3 - kilogram per cubic metre

Π - Pie

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 LIST OF FIGURES

FIGURE NO FIGURE NAME PAGE NO

5.1 Plastics 5
5.2 Heaters 9
5.3 C-Clamp 10
5.4 Hollow Rods 10
5.5 Shafts 11
5.6 Nuts and Bolts 11
5.7 Frame 12
6.1 Design 13
6.2 Working Model 14
6.3 Mold 15

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 CHAPTER 1

INTRODUCTION

The injection – molding machine consists of feeding the compounded plastic

material as granules, pellets or powder through the hopper at definite time
intervals into the hot horizontal cylinder where it gets softened. Pressure is
applied through a manually driven piston to push the molten material through a
cylinder into a mold fitted at the end of the cylinder. The molten plastic material
from the cylinder is then injected through a nozzle material from the cylinder is
then injected through a nozzle into the mold cavity.
Injection molding is a manufacturing process for producing parts by injecting
material into a mold. Injection molding can be performed with a host of
materials mainly including metals, (for which the process is called die-
casting), glasses, elastomers, confections, and most commonly thermoplastic
and thermosetting polymers. Material for the part is fed into a heated barrel,
mixed, and forced into a mold cavity, where it cools and hardens to the
configuration of the cavity. After a product is designed, usually by an industrial
designer or an engineer, molds are made by a mold- maker (or toolmaker)
from metal, usually either steel or aluminum, and precision-machined to
form the features of the desired part. Injection molding is widely used for
manufacturing a variety of parts, from the smallest components to entire body
panels of cars. Advances in 3D printing technology, using photopolymers which
do not melt during the injection molding of some lower temperature
thermoplastics, can be used for some simple injection molds.

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 CHAPTER 2

LITERATURE REVIEW

American inventor John Wesley Hyatt together with his brother Isaiah, Hyatt
patented the first injection molding machine in 1872. This machine was
relatively simple compared to machines in use today: it worked like a large
hypodermic needle, using a plunger to inject plastic through a heated cylinder
into a mold. The industry progressed slowly over the years, producing products
such as collar stays, buttons, and hair combs.
The German chemists Arthur Eichengrun and Theodore Becker invented the
first soluble forms of cellulose acetate in 1903, which was much less flammable
than cellulose nitrate. It was eventually made available in a powder form from
which it was readily injection molded. Arthur Eichengrun developed the first
injection molding press in 1919. In 1939, Arthur Eichengrun patented the
injection molding of plasticized cellulose acetate.
The industry expanded rapidly in the 1940s because World War II created a
huge demand for inexpensive, mass-produced products. In 1946, American
inventor James Watson Hendry built the first screw injection machine, which
allowed much more precise control over the speed of injection and the quality
of articles produced. This machine also allowed material to be mixed before
injection, so that colored or recycled plastic could be added to virgin material
and mixed thoroughly before being injected. Today screw injection machines
account for the vast majority of all injection machines. In the 1970s, Hendry
went on to develop the first gas-assisted injection molding process, which
permitted the production of complex, hollow articles that cooled quickly. This
greatly improved design flexibility as well as the strength and finish of
manufactured parts while reducing production time, cost, weight and waste.
The plastic injection molding industry has evolved over the years from
producing combs and buttons to producing a vast array of products for many
industries including automotive, medical, aerospace, consumer products, toys,
plumbing, packaging, and construction.

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 CHAPTER 3
PROBLEM DEFINITION

The principal advantage of injection molding is the ability to scale production.

Once the initial costs have been paid the price per unit during injection molded
manufacturing is extremely low. The price also tends to drop drastically as more
parts are produced. Other advantages include the following:

Injection Molding produces low scrap rates relative to traditional manufacturing

processes like CNC machining which cut away substantial percentages of an
original plastic block or sheet. This however can be a negative relative to
additive manufacturing processes like 3D printing that has even lower scrap
rates. Note: waste plastic from injection molding manufacturing typically comes
consistently from four areas: the sprue, the runners, the gate locations, and any
overflow material that leaks out of the part cavity itself (a condition called
“flash”).

A sprue is simply the channel that guides molten plastic from the nozzle of the
injection molding machine to the entry point for the entire injection mold tool.
It is a separate part from the mold tool itself. A runner is a system of channels
that meet up with the sprue, typically within or as part of the mold tool that
guides the molten plastic into the part cavities within the mold tool. There
are two principal categories of runners (hot and cold) which you can read about
here. Lastly, the gate is the part of the channel after the runner that leads
directly into the part cavity. After an injection mold cycle (typically only
seconds long) the entirety of the molten plastic will cool leaving solid plastic in
the sprue, runners, gates, part cavities themselves, as well as a little bit of
overflow potentially on the edges of the parts (if the seal isn’t 100% right).

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 CHAPTER 4
METHODOLOGY

The following procedure has been done during the design and fabrication stage:

1. Identify problems and requirements

2. Design

3. Drawing

4. Selection of suitable materials

5. Fabrication and assembly

6. Presentation and Report

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 CHAPTER 5
COMPONENTS AND MATERIALS

PLASTICS

Plastic is material consisting of any of a wide range of synthetic or semi-

synthetic organic compounds that are malleable and so can be molded into solid
objects.
Plasticity is the general property of all materials which can deform irreversibly
without breaking but, in the class of moldable polymers, this occurs to such a
degree that their actual name derives from this ability.
Plastics are typically organic polymers of high molecular mass, but they often
contain other substances. They are usually synthetic, most commonly derived
from petrochemicals, but many are made from renewable materials such as
polylactic acid from corn or cellulosic from cotton linters.

Figure 5.1 Plastics

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 Types of Plastic Material

 Thermoplastics:-Thermoplastics are the plastics that do not undergo

chemical change in their composition when heated and can be
molded again and again. They are easily molded and extruded
into films, fibers and packaging. Examples include polyethylene
(PE), polypropylene (PP) and polyvinyl chloride (PVC)

 Thermosetting plastics:-Thermosetting plastics which are formed by

heat process but are then set (like concrete) and cannot change
shape by reheating. They are hard and durable. Thermo sets can
be used for auto parts, aircraft parts and tires. Examples include
polyurethanes, polyesters, epoxy resins and phenol resins.

Table 5.1 Thermoplastic properties:

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Table 5.2 Thermosetting Properties

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 Characteristics:

 Light in weight

 Excellent resistance to stress and high resistant to cracking (i.e. it has

high tensile and compressive strength)
 High operational temperatures with a melting point of 160°C

 Excellent dielectric properties

 Non-toxic

 Easy to produce, assembly and an economic material

 It is often used in applications where rigidity and stiffness are needed. When
polyethylene is incapable of providing mechanical properties that are
specified, in many cases, it is polypropylene that takes its place.

Specifications of Plastic Material:

 Specific Gravity: 0.90

 Melting Point: 160°C

 Tensile Strength: 31.027 N/mm2

 Hardness: R95

 Rigid

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 HEATERS

Types of Heaters:-

1. Mica band heaters

2. Ceramic band heaters
3. Coil heaters

Band heaters are used in our project as they are economical and easy to use.

Figure 5.2 Band Heaters

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 C-CLAMP:

It is a mechanical apparatus used to fix an object to allow work to be performed on it.

It has two parallel jaws, one is fixed and the other is movable, threaded in and out by a
screw and lever.

Figure 5.3 C-Clamp

PLATE:

These plates are used for base and for support to the injection molding machine. The
die is placed on this plate.
Material: Mild Steel.

HOLLOW RODS:

It is used to store the plastic granules and the granules are heated with the help of
heater which is surrounded to the hollow rod.
Material: Mild Steel.

Figure 5.4 Hollow rod

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 SHAFTS:

A shaft is a rotating machine element, usually circular in cross section, which is used
to transmit power from one part to another, or from a machine which produces power
to a machine which absorbs power. These mild steel shafts are used as a plunger for
pressing the liquid plastic into the mould.
Material: Mild Steel.

Figure 5.5 Shaft

NUTS AND BOLTS:

Bolted joints are one of the most common elements in construction and
machine design. They consist of fasteners that capture and join other parts, a
secured with the mating of threads. These nuts and bolts are used for fixing
our frame of our project.
Material: Mild Steel

Figure 5.6 Nuts and bolts

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 FRAME:

Frames are mainly used for the support of the other components. This frame
gives the total support for the full assembly. It is made of mild steel plates of
required dimensions.
Material: Mild Steel.

Figure 5.7 Frame

PAINTS:

Paint is any liquid, liquefiable, or mastic composition that, after application

to a substrate in a thin layer, converts to a solid film. It is most commonly
used to protect, colour, or provide texture to objects. Paint can be made or
purchased in many colours and in many different types, such as watercolour,
synthetic, etc. Paint is typically stored, sold, and applied as a liquid, but most
types dry into a solid.

Table 5.3 Specifications of Material:

S.no Name Type Length Outer dia Inner dia

1. Plunger MS rod 40cm 33.5cm -
2. Barrel MS 15cm 35cm 34cm
3. Stand MS 40cm - -
4. Heater Mica 10cm 36cm 35cm
5. Die MS 5cm - -

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 CHAPTER-6
DESIGN, CALCULATION,WORKING MODEL &
COST ESTIMATION

Design is done in NX-11.The parts are designed individually in the NX-11

software and assembled in the same software.
The main options used in the software are:
1. Extrude
2. Hole
3. Chamfer
4. Surface modeling.
5. Assembly
6. 3D- view

3D-VIEW

Figure 6.1 Design

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 CALCULATION

Force Applied on Plunger:

Density of plunger (Mild Steel) = 770 kg/m3
Volume of Plunger (V) =πr2h m3
V=π*(0.16)2*0.4
V=0.032 m3
Density = Mass/Volume
Mass=Density *Volume
Mass=770*0.032
Mass=24.64 kg
Force= Mass*Acceleration
Force= 24.64*9.81
Force=241.71 N
WORKING MODEL:
The Working model and the die is shown in the below figures

Figure 6.2 Working Model

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 Figure 6.3 Die

The Detailed cost estimation is shown in the below table 6.1

Table 6.1 Cost Estimation:
S.no Part Quantity Price (Rs)
1 Band Heater 1 350.00
2 Temperature controller 1 350.00
3 C-Clamp 1 500.00
4 Mild steel rod 1 50.00
5 Hollow rod 1 50.00
6 Mild steel plates 4 300.00
7 Mild steel square rod 2 100.00
8 Nuts and Bolts 4 50.00
9 Paints 2 150.00
10 Plastic granules(bottle) 1 100.00
11 Others - 1000.00
12 Total - 3000.00

Total cost of the project is Rs: 3,000/-

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 CHAPTER 7

MECHANISM & FABRICATION

MECHANISM:
The injection – moulding machine is shown in the figure consists
of feeding the compounded plastic material as granules, pellets or powder
through the hopper at definite time intervals into the hot vertical cylinder where
it gets softened. Pressure is applied through a manually driven ram or plunger to
push the molten material through a cylinder into a mould fitted at the end of the
cylinder. The molten plastic material from the cylinder is then injected through
a nozzle material from the cylinder is then injected through a nozzle into the
mould cavity.

FFABRICATION:
Machine fabrication is a value added process that involves the
construction of machines and structures from various raw materials. The
process of fabrication started in the machine shop on the basis of engineering
drawings and the availabilities of the shop with respect to machining (facing,
drilling, welding, taper turning etc...)

Metal fabrication jobs usually starts with drawings including precise

measurements then, to the fabrication stage and finally to the assembly the
project.

The following steps were followed in fabricating this project:

Stage 1: Cost Estimation

Stage 2: Materials selection

Stage 3: Fabrication of individual parts

Stage 4: Final Assembly

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Fabrication process for this project contains the following machining
processes:
1. Marking.
2. Cutting.
3. Lathe operations (turning, facing, chamfering).
4. Welding.
5. Assembling.
Marking:
Marking is the act, process, or an instance of making or giving a mark. So
marking is done to know where to cut, drill, weld, machine, etc. the work
piece with correct dimensions. So initially the work pieces are taken and
marked with the design specifications.

Cutting:
Cutting is the separation of a physical object, into two or more portions, through
the application of an acutely directed force.
Implements commonly used for cutting are the knife and saw, or in medicine
and science the scalpel and microtome. However, any sufficiently sharp object
is capable of cutting if it has a hardness sufficiently larger than the object being
cut, and if it is applied with sufficient force. Even liquids can be used to cut
things when applied with sufficient force.
Lathe operations:
A lathe is a tool that rotates the work piece about an axis of rotation to performs
various operations such as cutting, sanding, knurling, drilling, deformation,
facing, turning, with tools that are applied to the work piece to create an object
with symmetry about that axis.
Lathes are used in woodturning, metalworking, metal spinning, thermal
spraying, parts reclamation, and glass-working. Lathes can be used to
shape pottery, the best-known design being the potter's wheel. Most suitably
equipped metalworking lathes can also be used to produce most solids of
revolution, plane surfaces and screw threads or helices.. The work piece is
usually held in place by either one or two centers, at least one of which can
typically be moved horizontally to accommodate varying work piece length

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 Welding:
Arc welding is a process that is used to join metal to metal by using electricity
to create enough heat to melt metal, and the melted metals when cool result in a
binding of the metals. It is a type of welding that uses a welding power
supply to create an electric arc between an electrode and the base material to
melt the metals at the welding point. They can use either direct (DC)
or alternating (AC) current, and consumable or non-consumable electrodes. The
welding region is usually protected by some type of shielding gas, vapor, or
slag. Arc welding processes may be manual, semi-automatic, or fully
automated.

Assembling:
Assembly of components is the process of combining the part or subassemblies
to form the final product. Individual parts or subassemblies act as a single unit.
For example, a single-part base plate and a multipart air cylinder subassembly
are both components when placed in an assembly.

The behavior and characteristics of a component depend on how it was created.

The principles of assembly are as follows:

 Place the tools and the men in the sequence of the operation so that each
component part shall travel the least possible distance while in the
process of finishing.

 Use work slides or some other form of carrier so that when a workman
completes his operation, he drops the part always in the same place which
place must always be the most convenient place to his hand and if
possible have gravity carry the part to the next workman for his own.

 Use sliding assembling lines by which the parts to be assembled are

delivered at convenient distances.

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 CHAPTER 8
DISCUSSIONS
VARIOUS PROBLEMS AND SOLUTIONS:
 Die Setting
 Stop the molten material leakage in nozzle
 For Diff. die different arrangement of injection mechanism

ADVANTAGES:
 Cheaper and easily available material used
 Quick response
 No fire hazard problem due to over loading
 Continuous operation is possible without stopping
 High Production Rate
 Occupies less floor space
 Fastest cycle time in case of rubber, the rubber is warmed before going
into the mold..
 Alternative for plastic cups and plates

FUTURE SCOPE:
 Plastic injection moulding industry is now facing the very heavy
competition; most of the plastic injection moulding companies is working
on mercy profits and low technologies.
 Even if your machine are high speed, but if you are in shortage of
automation system in your injection moulding plants, then you need a lot of
labor to pick up the moulded plastic components from the machine and you
need to stack or collect them before packing. All these need labors and this
will reduce the production capacity, in the same time the labor cost will be
highly increased.
 In the project we have used manual plunger arrangement for pressing the
molten plastic instead of that we can have hydraulic arrangement for the
automatic control that will reduce production time.
 Also for the batter and quick heating to melt the plastic insulation can be
done which will reduce the heat loss.

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 CHAPTER 9

CONCLUSION

Due to its low cost this working model can be successfully inducted in small
scale molding units and can be used to manufactured small plastic components
at an acceptable cycle rate with in an effective cost component. It is one of the
most important processes for plastic and it has a very wide list of products can
be produced, which makes it very versatile.In injection moulding less material is
wasted and final product is of low cost. Injection molding is an extremely
useful tool for mass-producing polymer parts once the parameters for its ideal
operation have been ascertained. Being a net-shape process, Metal Injection
Molding is most competitive where costly machining operations can be avoided
and where the number of parts required is sufficiently high to justify the cost of
the mould.

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 CHAPTER 10

REFERENCES

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[5] C. Sasikumar, S. Srikanth, S.K. Das. “Analysis of premature failure of

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[6] G. Lucchetta, P.F. Bariani, W.A. Knight. “A New Approach to the

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