A 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
3. 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
4. Granulated material is fed from hooper
Temp. – 150 to 300 degree c
Pressure-100 Mpa to 150 Mpa
Moulding die is water cooled
Two principal units—
1.Plastic injection unit
-melt and homogenize the polymer
-inject the liquid plastic into mould cavity
-hold two halves
-to keep the mould closed during injection
7. ADVANTAGES and application s OF INJECTION
Higher speed (Used for mass production)
Complicated shape with high accuracy.
Material wastage is low.
Cups, Chairs, Toys, Container, Knobs,
Automobile parts, Air conditional parts,
8. BLOW MOULDING
It is a moulding process in which air pressure
is used to inflate soft plastic into a mould
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
Pressure :- 400 – 800 kPa.
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
14. 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