Injection Moulding

INJECTION MOULDINGSurjit Singh, Satnam Singh, Sanjeev Kumar, Paramjeet Kaur

PROJECT SELECTION

There is great awareness among Indian middle class & upper class for comfortable life style considering the requirements of modernlife style where plastics play & important role , we have selected this technique name “Injection molding ˝ which is use widely world wide.

By the help of this technique, we can manufacture component of different design while choosing this product and technique we have considered some special feature lie design, durability, cart etc.

We have selected this technique because there is no such as technique available in industrial market, so it will be a great technique in industrial market & will have considerable expert potential.

This technique is known as injection molding .This technique is much cheaper than other .

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INTRODUCTION OF INJECTION MOULDING

Injection molding is a manufacturing technique for making

part from plastic material. Molten plastic is injected at

higher pressure into a mould which is inverse of the

desired shape. The mould is made by mould maker from

metal, usually either steel or aluminum, and precision

machined to from the features of the desired part. Injection

molding is very widely used for manufacturing a variety of

parts, like cosmetic,food & medicine packaging etc.

Considerable thought is put into the design of

molded parts & there moulds , the ensure that the parts

will not be trapped in the mould , that the moulds can be

completely filled before the molten resin solidities , & to

minimize imperfection in the parts which can occur due to

peculiarities of the process.

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Moulds separate in to at least two halves called the

core & the cavity to permit the part to be extracted ; in

general the shape of a part to be extracted; in general the

shape of a part must be such that is will not be locked in to

the mould . For example, sides of objects typically can not

be parallel with the direction of draw the direction in which

the core & cavity separate from each other. They are

angled slightly; examination of must house hold objects

made from plastic will show this accept of design, known

as draft. Parts that are ˝ bucket – like ˝ tend to shrink on to

the core while cooling & after the cavity is pulled away are

typically ejected using pins. More complex parts are

formed using more complex moulds , which may require

moveable sections which are inserted in to the mould to

form particular features that can not be formed using only

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a core & a cavity , but are than with drawn to allow the part

to be released.

The resin, or raw material for injection molding, is usually

in pellet from, and is electrically melted shortly before

being injected in to the mould . The channels through

which the plastic flow towards the chamber will also

solidify, forming & attached frame. This frame is

composed of the sprue , which is the main channel from

the reservoir of molten resin, parallel with the direction of

draw , & runners , which are perpendicular to the direction

of drawn , & the used to convey molten resin to the gates,

or points of injection. The sprue & runner system can be

cut off & recycled . Some moulds are design such that it is

automatically stripped from the part through action of the

mould .

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The quality of the moulded part depend on the quality of

mould , the care taken during the moulding process, and

upon details of the design of the parts it self . It is essential

that the molten resin be at just the right pressure and

temp. , so that it flow easily to all part of the mould . The

part of the mould must also come together extremely

precisely , otherwise small leakages of molten plastic can

from a phenomenon known as flash . When filling a new or

unfamiliar mould for the first time , where shot size for that

particular mould is unknown , a technician should reduce

the nozzle pressure so that the mould fills , but dose not

flash . Then , using that now - known shot volume

pressure can be raised with out fear of damaging the

mould .

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Injection molding process

Injection moulding is the process of forcing melted plastic

in to a mould cavity. One injection moulding often used in

mass production & prototyping injection mould. The first

injection moulding m/cs were built in the 1930 s.

There are six major steps in the injection moulding

process:

1. Clamping: - In an injection moulding machine

clamping is the important part. Its main function to

closing the mould adds the time of the injection.

2. Injection :- During the injection phase ,

plastic material , usually in the from of pallets , are

low pallets feed in to the cylinder where they are

heated until they reach molten form the heating

cylinder there is a motorized screw that mixes the

molten pallets and material has accumulated in front

of the screw , the injection process being . The

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sprue, while the pressure and speed are controlled

by the screw.

3. Dwelling: - The dwelling phase consists of a

pause in the injection process. The molten plastic is

applied to make sure all of the mould cavities are

filled.

4. Cooling: - The plastic is allowed to cool to its

solid form with in the mould.

5. Mould opening: - The clamping unit is

opened, which separates the two halves of the

mould.

6. Ejection: - An ejecting rod and plate eject the

finished piece of the mould. The unused space

future mould.

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ADVANTAGES OF INJECTION MOULDING

High production rates

Low Power Consumption

Good Accuracy

Low Maintenance Charge

High tolerances are repeatable

Wide range of materials can be used

Low labour costs

Minimal scrap losses

Little need to finish parts after moulding

DISADVANTAGES OF INJECTION MOULDING

Expensive equipments investment

Running cost may be high

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Parts must be designed with moulding consideration

INJECTION MOULDING

The process is used to produce large quantities of

identical plastic items. One of the most common types of

thermoplastics used in injection moulding is

polypropylene.

Injection moulding is the most important plastics

manufacturing process. It produces such small products

as bottle top; sink plugs, cosmetic products,&

pharamaseutical products. It is also used to manufacturer

larger items such as buckets & milk crates. Familiar

products manufactured by injection moulding include

cosmatic products ( like fair & lovely cap, gulabri container

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cap & base, veet spatulla, himamiwashar cap & food

packazing products like bornvita cap, horlicks cap,

Jemsball top & bottom etc.

The process can be even mould such large

items as 1Kg Cap of Bouranvita & medicines box.

Injection moulding used to be operated by

people on the factory floor but these days it is a form of

highly automated from of production. The whole process is

controlled by a central processing unit.

Stage 1:-

Granulated or powdered thermoplastic is fed

from a hopper in to the injection moulding machine.

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Stage 2:-

The injection moulding machine consists of a

hollow steel barrel, containing a rotating screw. The screw

carries the plastic along the barrel to the mould. Heaters

surround the barrel melt the plastic as it travels along the

barrel.

Stage 3:-

The screw is forced back as the melted plastic

collects at the end of the barrel .once enough plastic has

collected a hydraulic ram pushes the screw forward

injecting the plastic through a sprue in to a mould cavity .

The mould is warmed before injecting and the plastic is

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injected quickly to prevent it from hardening before the

mould is full.

Stage 4:-

Pressure is maintained for a short time (dwell

time) to prevent the material creeping back during setting.

This prevent shrinkage and hollows, therefore giving a

better quality product. The moulding is left to cool before

removing (ejected) from the mould. The moulding is takes

on the shape of the mould cavity. The image below shows

an injection moulding machine.

A mould used for injection moulding may cost

thousands of moulding can be produced from a single

mould. This results in the low cost of each moulding.

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It used to be the case that when a new type of

casting was needed a brand new die heads to be made.

Modern dies and moulds are made from a number of inter

changeable parts. This allows the shape of the mould to

be altered.

The dies or moulds used in the process are made

from ally stainless steel. These special alloy steel moulds

are made in a number of parts to allow the moldings to be

easily removed. Plastics that are used in injection

moulding include low density polyethylene (LDPE), high

density polyethylene, Polypropylene (PP).

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Key suppliers of raw material

Reliance India ltd. PP Haldia petro chemical HDPE Helene HDPE IPCL PP Indian Oil LDPE

Grades of material :-

Material Grades

PP H110MAPP B120MAPP R120MKHDPE 5818-5201LDPE SRM100NCPE PE060,CMC PNT

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SPECIFICATION OF MACHINE

1) Ferromatic Omega 550

2) Ferromatic Omega 660

3) Polo 250

4) Windser 50/180

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Conclusion

Injection moulding machine has been available as a

processing method for big plastic products for about 40

years.

With in last 10 to 15 years there has been

dramatic change.

Engineers and designers are taking a fresh interest in the

process because of the scope it offers for the production

of relatively inexpensive, complex shape with low levels of

molded in stress. Material suppliers are continually

developing new grades of plastics as well as a wider

selection of material suited to the process. In addition,

machinery suppliers are producing more sophisticated

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moulding equipment so that the molder now has control

over the process that was thought impossible.

The article of bigger size is to be moulded the

heating , cooling time will be rised significantly. Heating

little but more time will be while cooling time will be around

6-8 sec. The total time for full cycle will be nearly 18 sec.

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Documents

Injection Moulding