INDUSTRIAL TRAINING REPORT

AALL--FFEELLAAIIJJ PPLLAASSTTIICCSS

BY

BBIIBBIINN KK BBAABBYY

Final Year B.Tech

(Mechanical Engineering)

2013-14

DEPARTMENT OF MECHANICAL ENGINEERING

SAINTGITS COLLEGE OF ENGINEERING Kottukulam Hills, Pathamuttom P .O, Kottayam 686532, Kerala.

Tel : +91-481-2436169, 0481-2436170, Fax : 0481-2430349

E-mail : saintgitsengg@sify.com, Website : www.saintgits.org

ACKNOWLEDGEMENT

I would like to begin by expressing my whole heated gratitude to God the Almighty for being

the light in my journey to complete this Industrial training with satisfaction.

I am highly grateful to Mr Fredy Fernandes, Production Manager for his valuable guidance,

Mr Ravi for enriching me about the working of the factory and to all the supervisors and staff

for taking their valuable time to explain the various processes

CONTENTS

SERIAL NO. TITLE PAGE NO.

1 Raw Materials 1

1.1 Polypropylene (PP) 1

1.2 High Density Polyethylene

(HDPE) 1

1.3 Polystyrene (Ps) 1

2 Process Layout 2

3 Blending 3

3.1 What Is Blending? 3

3.2 Why Blend? 3

3.3 Blenders Used 4

4 Injection Molding 5

4.1 Introduction 5

4.2 Process And Equipment 5

4.3 Cycle For Injection 7

4.4 The Mold 8

4.5 Injection Molding Machines 9

5 Blow Molding 11

6 Factory Layout 13

7 Screen Printing 14

8 Safety Precaution

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1

CHAPTER 1

1 RAW MATERIAL

1.1. Polypropylene (PP)

Also known as polypropene is a thermoplastic polymer used in a wide variety of applications

including, plastic parts and reusable containers of various types.

Features

Food Contact Acceptable, Good Impact Resistance, Good Stiffness, High Flow, High Impact

Resistance, High Stiffness, Resistant to Fatigue

Polypropylene is most commonly used for plastic moldings, wherein it is injected into a mold

while molten, forming complex shapes at relatively low cost and high volume; examples include

bottle tops, bottles, and fittings.

1.2. High Density Polyethylene (HDPE)

High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene

thermoplastic made from petroleum.

Known for its large strength to density ratio, HDPE is commonly used in the production of plastic

bottles, and corrosion-resistant piping . HDPE is commonly recycled.

Features

It’s stronger than standard polyethylene, Acts as an effective barrier against moisture, Resists

insects, rot and other chemicals, It is easily recyclable

The two main grades:

Injection Grade and Blow Grade

1.3. Polystyrene (PS)

Polystyrene (PS) is a synthetic aromatic polymer made from the monomer styrene, a liquid

petrochemical.

As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if

heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled

Features

Polystyrene can be rigid or foamed, general purpose polystyrene is clear, hard and brittle,

Polystyrene can be naturally transparent, but can be colored with colorants

The two main grades :

High Impact Polystyrene (HIP) and b. Styrene Acrylonitrile (SAN) Plastic

2

CHAPTER 2

PROCESS LAYOUT

BLENDING

PROCESS MACHINING

PACKING/STORAGE

LOADING FOR DISPATCH

EXPORT

3

CHAPTER 3

3 BLENDING

3.1 What is blending?

Blending is an efficient, thorough and automated way to combine material ingredients, in pre-

determined proportions, and then mix them together in preparation for the production of plastic

parts or products. Materials to be blended may be metered into the blend by quantity (volumetric

blending) or by weight (gravimetric blending).

3.2 Why Blend?

Every processor has a choice in how to feed material to their process in order to produce saleable

product with the characteristics they require.

In the past, most processors purchased materials that were pre-compounded into specialized pellets

to produce the specific colour and properties that they needed. It was a very simple process then, to

simply feed these customized compounds into their process. However, the cost of these custom

compounds was significantly higher than the cost of the individual raw ingredients. In addition,

since many processors changed the material, the colour and the characteristics of the products they

produced, keeping quantities of all the uniquely compounded materials they processed created an

inventory nightmare.

The solution? Blending.

By using a precision device for mixing materials together, as needed, inventories are reduced to

only the necessary raw materials for the process, there is no costly pre-compounding step and

reground material can be rolled directly into the process as required, with no disruption in the

process flow. This results in significantly lower material costs, less inventory of materials, more

efficient usage of reground material and, if the correct blending/dosing device is utilized, an

increase in part or product quality and 100% repeatable results.

4

3.3 BLENDERS USED AL – FELAIJ PLASTICS.

The Blenders used here have two Slow rotating drum, that makes the product slide down gently on

the smooth internal walls, performing a mixing effect.

The blenders here are used for mixing the Colour with the raw material.

It is also used to add materials to raw material to increase strength.

Each container has a capacity of about 100kg, 4 Bags(Each of 25 kg)

1 and half cup of colouring material is added

The compound added – Colour and additive master batches - EMKOLOR

The drums are rotated till its mixed thoroughly.

5

CHAPTER 4

4.1 INJECTION MOLDING

Injection molding is a process in which a polymer is heated to a highly plastic state and forced to

flow under high pressure into a mold cavity, where it solidifies. The molded part, called a molding,

is then removed from the cavity. The process produces discrete components that are almost always

net shape. The production cycle time is typically in the range 10 to 30 seconds, although cycles of

one minute or longer are not uncommon. Complex and intricate shapes are possible with injection

molding. The challenge in these cases is to design and fabricate a mold whose cavity is the same

geometry as the part and which also allows for part removal. Part size can range from about 50 g (2

oz) up to about 25 kg (more than 50 lb).

4.2 PROCESS AND EQUIPMENT

Equipment for injection molding evolved from metal die casting.

An injection molding machine consists of two principal components:

(1) The plastic injection unit and, (2) The mold clamping unit.

The injection unit is much like an extruder. It consists of a barrel that is fed from one end by a

hopper containing a supply of plastic pellets. Inside the barrel is a screw whose operation surpasses

that of an extruder screw in the following respect: in addition to turning for mixing and heating the

polymer, it also acts as a ram which rapidly moves forward to inject molten plastic into the mold. A

nonreturn valve mounted near the tip of the screw prevents the melt from flowing backward along

the screw threads. Later in the moulding cycle the ram retracts to its former position. Because of its

dual action, it is called a reciprocating screw. To summarize, the functions of the injection unit are

to melt and homogenize the polymer, and then inject it into the mold cavity

The melting of the polymer in the injection system is obtained by zones of electric heaters

surrounding the barrel containing a supply of plastic pellets. The temperature in each zone is set

according to the requirement in the Temperature controller or Pyrometer. Each zone is provided

with a Thermocouple that sends electric signals to the temperature controller. The temperature

controller then controls an electromagnet that’s used to open or close the contactor that is

connected to the Electric heater in each zone.

Each zone is represented as HN, H1, H2, H3, H4, etc.

6

The clamping unit is concerned with the operation of the mold. Its functions are to:

(1) Hold the two halves of the mold in proper alignment with each other;

(2) Keep the mold closed during injection by applying a clamping force sufficient to resist the

injection force; and

(3) Open and close the mold at the appropriate times in the molding cycle.

The clamping unit consists of two platens, a fixed platen and a movable platen, and a mechanism

for translating the latter. The mechanism is basically a power press that is operated by hydraulic

piston or mechanical toggle devices of various types

7

4.3 CYCLE FOR INJECTION

The cycle for injection molding of a thermoplastic polymer proceeds in the following sequence. Let

us pick up the action with the mold open and the machine ready to start a new molding:

(1) Mold is closed and clamped.

(2) A shot of melt, which has been brought to the right temperature and viscosity by heating and by

the mechanical working of the screw, is injected under high pressure into the mold cavity. The

plastic cools and begins to solidify when it encounters the cold surface of the mold. Ram pressure

is maintained to pack additional melt into the cavity to compensate for contraction during cooling.

(3) The screw is rotated and retracted with the nonreturn valve open to permit fresh polymer to

flow into the forward portion of the barrel. Meanwhile, the polymer in the mold has completely

solidified.

(4) The mold is opened, and the part is ejected and removed.

8

4.4 THE MOLD

The mold is the special tool in injection molding; it is custom-designed and fabricated for the given

part to be produced. When the production run for that part is finished, the mold is replaced with a

new mold for the next part.

Two-Plate Mold. The conventional two-plate mold consists of two halves fastened to the two

platens of the molding machine's clamping unit. When the clamping unit is opened, the two mold

halves open, as shown in (b). The most obvious feature of the mold is the cavity, which is usually

formed by removing metal from the mating surfaces of the two halves. Molds can contain a single

cavity or multiple cavities to produce more than one part in a single shot. The figure shows a mold

with two cavities. The parting surfaces (or parting line in a cross-sectional view of the mold) are

where the mold opens to remove the part(s).

In addition to the cavity, there are other features of the mold that serve indispensable functions

during the molding cycle. A mold must have a distribution channel through which the polymer

melt flows from the nozzle of the injection barrel into the mold cavity. The distribution channel

consists of (1) a sprue, which leads from the nozzle into the mold; (2) runners, which lead from

the sprue to the cavity (or cavities); and (3) gates that constrict the flow of plastic into the cavity.

There are one or more gates for each cavity in the mold.

An Ejection system is needed to eject the molded part from the cavity at the end of the molding

cycle. Ejector pins built into the moving half of the mold usually accomplish this function. The

cavity is divided between the two mold halves in such a way that the natural shrinkage of the

molding causes the part to stick to the moving half. When the mold opens, the ejector pins push the

part out of the mold cavity.

A cooling system is required for the mold. This consists of an external pump connected to

passageways in the mold, through which water is circulated to remove heat from the hot plastic.

Air must be evacuated from the mold cavity as the polymer rushes in. Much of the air passes

through the small ejector pin clearances in the mold. In addition, narrow air vents are often

machined into the parting surface; only about 0.03 mm (0.001 in.) deep and 12 to 25 mm (0.5 to

1.0 in.) wide, these channels permit air to escape to the outside but are too small for the viscous

polymer melt to flow through.

9

4.5 INJECTION MOLDING MACHINES :

Injection molding machines differ in both injection unit and clamping unit. The name of the

injection molding machine is generally based on the type of injection unit used.

Injection Units. Two types of injection units are widely used today. The reciprocating-screw

machine is the most common. This design uses the same barrel for melting and injection of plastic.

The alternative unit involves the use of separate barrels for plasticizing and injecting the polymer.

This type is called a screw-preplasticizer machine or two-stage machine. Plastic pellets are fed

from a hopper into the first stage, which uses a screw to drive the polymer forward and melt it. This

barrel feeds a second barrel, which uses a plunger to inject the melt into the mold. Older machines

used one plunger-driven barrel to melt and inject the plastic. These machines are referred to as

plunger-type injection molding machines.

Two alternative injection systems to the reciprocating screw: (a) screw preplasticizer, and (b)

plunger type

10

Clamping Units. Clamping designs are of three types: toggle, hydraulic, and hydro- mechanical.

Toggle clamps include various designs. An actuator moves the crosshead forward, extending the

toggle links to push the moving platen toward a closed position. At the beginning of the movement,

mechanical advantage is low and speed is high; but near the end of the stroke, the reverse is true.

Thus, toggle clamps provide both high speed and high force at different points in the cycle when

they are desirable. They are actuated either by hydraulic cylinders or ball screws driven by electric

motors. Toggle-clamp units seem most suited to relatively low-tonnage machines. Two clamping

designs:

(a) one possible toggle clamp design (1) open and (2) closed; and (b) hydraulic clamping (1) open

and (2) closed. Tie rods used to guide moving platens not shown.

Hydraulic clamps are used on higher-tonnage injection-molding machines, typically in the range

1300 to 8900 kN (150 to 1000 tons). These units are also more flexible than toggle clamps in terms

of setting the tonnage at given positions during the stroke. Hydro-mechanical clamps are

designed for large tonnages, usually above 8900 kN (1000 tons); they operate by (1) using

hydraulic cylinders to rapidly move the mold toward closing position, (2) locking the position by

mechanical means, and (3) using high pressure hydraulic cylinders to finally close the mold and

build tonnage.

11

CHAPTER 5

BLOW MOLDING

Blow molding is a molding process in which air pressure is used to inflate soft plastic into a mold

cavity. It is an important industrial process for making one-piece hollow plastic parts with thin

walls, such as bottles and similar containers. Since many of these items are used for consumer

beverages for mass markets, production is typically organized for very high quantities. The

technology is borrowed from the glass industry with which plastics compete in the disposable or

recyclable bottle market.

Blow molding is accomplished in two steps: (1) fabrication of a starting tube of molten plastic,

called a parison (same as in glass-blowing);the material has a MFI – 4(Melt Flow Index) and (2)

inflation of the tube to the desired final shape. Forming the parison is accomplished by either of

two processes: extrusion or injection molding.

Extrusion Blow Molding. This form of blow molding consists of the cycle illustrated below. In

most cases, the process is organized as a very high production operation for making plastic bottles.

The sequence is automated and usually integrated with downstream operations such as bottle filling

and labelling. It is usually a requirement that the blown container be rigid, and rigidity depends on

wall thickness among other factors.

Extrusion blow molding: (1) extrusion of parison; (2) parison is pinches at the top and sealed at the

bottom around a metal blow pin as the two halves of the mold come together; (3) the tube is

inflated so that it takes the shape of the mold cavity; and (4) mold is opened to remove the

solidified part.

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Materials and Products. Blow molding is limited to thermoplastics. Polyethylene is the polymer

most commonly used for blow molding; in particular, high density and high molecular weight

polyethylene (HDPE and HMWPE). In comparing their properties with those of low density PE

given the requirement for stiffness in the final product, it is more economical to use these more

expensive materials because the container walls can be made thinner. Other blow moldings are

made of polypropylene (PP), polyvinylchloride (PVC), and polyethylene terephthalate.

Disposable containers for packaging liquid consumer goods constitute the major share of products

made by blow molding; but they are not the only products. Other items include large shipping

drums (55 gallon) for liquids and powders, large storage tanks (2000 gallon), automotive gasoline

tanks, toys, and hulls for sail boards and small boats. In the latter case, two boat hulls are made in a

single blow molding and subsequently cut into two open hulls

13

CHAPTER 6

FACTORY LAYOUT

14

CHAPTER 7

SCREEN PRINTING

Screen printing is used to print the required advertisement or images on the plastic bottles

depending on the requirements of the customer. Two types of paints are mainly used in this

process:

15

1. UV paint and 2. Normal paint

The different steps that are used in screen printing on bottles are:

1. Preparation of screen

- The screen which is made of a special type of cloth material called Silco and is attached to a

wooden frame using CSP FRAME ADHESIVE , 2- COMPONENT.

- The screen shampoo 711 is used for cleaning the screen

- A DUAL CURE EMULSION UR 720 HV is used to coat the screen, three times outside and two

times inside .

2. A negative image is placed on a light source.

3. The screen with the coating is placed on the Negative image over the light source for 4 minutes.

4. The image is then formed on the screen and is then mounted on the machine for printing.

5. The bottles to be printed are fed into a storage compartment.

6. They then pass through a conveyer section and are arranged in lines.

7. A laser and Photo sensor that is used for the correct alignment of the bottles before printing.

8. Air section plugs is used to turns the bottle depending upon the signal given by the laser and

photo sensor.

9. The bottles pass through a gas heater that is used to heat the bottles before the screen printing so

that the paint sticks on properly.

10. The first brush is used to accumulate the paint and the other brush to print it on the bottles.

11. The bottles are brought into UV chamber and exposed to UV Radiation.

12. The bottles are the packed and stored.

16

CHAPTER 8

SAFETY PRECAUTION

1. Always contact machine builder before altering electrical or hydraulic system.

2. Do not operate the machine unless thoroughly instructed on safety rules and operation.

3. When working on machine for other than molding operations shaft of motor and turn disconnects to

“OFF” position.

4. DANGER- Do not operate with guard removed.

5. High Voltage before servicing turn off and lock main power disconnect and all circuits powered by

an external source. Do not modify electric or hydraulic circuits unless authorized buy manufacturer.

This machine may be under remote control. Earth ground the machine and electric power before

turning on power.

6. Additional guards, ventilation system and other safety equipment may be required. The employer

must add guarding to provide protection from potential pinch points created by injectors, cores and

other mold components.

7. WARNING FOR INJECTION MOLDING:

Rotating screw – don’t operate with hopper removed or put hand or feet into opening.

High pressure molten material , stand clear and wear protective gear when purging and servicing

injector system.

High voltage, high temperature, shutoff power when working on covers chamber bands and wiring.

Operating and service personnel must:

Always: Read and obey all instructions on the machine and in the user’s manual.

Always: Wear approved safety glasses or face shield safety shoes, and any other personnel protective

equipment specified by your employer.

Always: Stop the machine before making adjustments, cleaning the part drop area or any other area,

performing maintenance or service, or if you suspect a malfunction.

Always: Open the operator’s gate before reaching into the machine or to remove molded part or runners.

Never: Operate or service the machine if affected by alcohol, drugs or other substances or conditions

which decreases alertness or judgment.

Never: Reach over , under or around guards while the machine is in operation.

Never: Wear a ring or other jeweler necktie, or loose fitting clothing, or a long unrestrained hair style.

Never: Climb on machine.

Never: Operate the machine unless all operation instructions are understood and all guards, interlocks,

covers, safety devices or circuits and protective components are in place and functioning properly.

Don’t remove or Disfigure any instruction plates. Failure to follow these instructions may result in

serious personal injuries.

17

THANK YOU