THERMOPLASTICS

MADE BY – ROHIT SINGH S . E MECHANICAL(2013-2017) ARMY INSTITUTE OF TECHNOLOGY

THERMOPLASTICSA thermoplastic, also called a thermosoftening plastic is a polymer which becomes pliable or moldable above a specific temperature and returns to a solid state upon cooling.

METHODS OF MOULDING

INJECTION MOULDING

THERMOFORMING

EXTRUSION

BLOW MOULDING

INJECTION MOULDING PROCESS

Injection moulding is the process in which a polymer is heated to a highly plastic state and forced to flow under high pressure in mould cavity , where it solidifies.

Granulated material is fed from hooperTemp. – 150 to 300 degree c Pressure-100 Mpa to 150 MpaMoulding die is water cooledTwo principal units—

1.Plastic injection unit

-melt and homogenize the polymer

-inject the liquid plastic into mould cavity

2.Clamping unit

-hold two halves

-to keep the mould closed during injection

PLUNGER TYPE INJECTION MOULD

SCREW TYPE INJECTION MOULD

ADVANTAGES and application s OF INJECTION MOULDING

Advantages:- Faster process. Higher speed (Used for mass production) Complicated shape with high accuracy. Material wastage is low. Applications:- Cups, Chairs, Toys, Container, Knobs,

Automobile parts, Air conditional parts, Eletrical fitting.

BLOW MOULDING It is a moulding process in which air pressure

is used to inflate soft plastic into a mould cavity.

Blow moulding performed in two steps:

1). Fabrication of starting tube of molten plastic which is called as parison.

2). Inflation of the tube to the required foundation. Pressure :- 400 – 800 kPa.

APPLICATIONS

THERMOFORMING It is a series of processes for forming thermo

plastic sheet or film over a mould. With the application of heat and pressure.

Used in packaging of consumer product and to fabricate large parts like bath tubs , internal door liners etc.

Two methods of Thermoforming

1. Vacuum Forming

2. Pressure Forming

VACUUM FORMING

Plastic sheet thickness-0.125 to 3.2 mmTemperature- 55 to 90 degree c

PRESSURE FORMING

ADVANTAGES OF THERMOFORMING Initial setup cost is low. Intricate shapes are easily formed.Production cost is low.Less thermal stress during process.Holes less than equal to 0.5mm.Cost of tooling is low.Aluminium moulds are used.Example:- Jelly containers, luggage

belts,Refrigerator inner pannels

THERMOFOFMING PRODUCTS

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