Thermoplastics are polymers that become moldable above a certain temperature and harden upon cooling. Injection molding is a common molding process where thermoplastic is heated, injected into a mold under high pressure, and solidifies. It is used for mass production of parts with complex shapes and high accuracy like toys, containers, and automobile parts. Blow molding uses air pressure to inflate hot plastic into a mold, while thermoforming shapes heated plastic sheets over molds using vacuum or pressure forming. Both processes are used to make packaging and large plastic items.

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

2. THERMOPLASTICS
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
solidifies.

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
2.Clamping unit
-hold two halves
-to keep the mould closed during injection

5. PLUNGER TYPE INJECTION MOULD

6. SCREW TYPE INJECTION MOULD

7. 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.

8. 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.

9. APPLICATIONS

10. 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

12. VACUUM FORMING
 Plastic sheet thickness-0.125 to 3.2 mm
 Temperature- 55 to 90 degree c

13. 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

15. THERMOFOFMING PRODUCTS