All credit goes to the creators, my colleagues.

1. INJECTION
MOULDING

2. Process analyzing
•Definition
Injection molding is a manufacturing
process for producing parts from both
thermoplastic and thermosetting plastic or
other materials.

3. Mold designing
• Mold is a hollowed out bock used when component are to be made from
plastic or rubber glass etc. Usually mold is made from metal such as steel or
aluminum.
• main functions of mold
• To give desired shape to the part
• Cool and cure the material
• Eject the part properly
• To distribute the melt
• To withstand clamping forces and injection pressure

4. Types of plastics used
Thermoplastics
Thermoplastics are the plastics that do not undergo chemical
change in their composition when heated and can be molded
again and again.
Thermosetting plastics-
thermosets can melt and take shape once; after they have
solidified , they stay solid . In the thermosetting process, a
chemical reaction occurs that is irreversible.

5. Injection molding machine

6. Main components
• Hopper-
thermoplastic material is supplied in form of small
palates.The gravity fed into the barrel and the screw
assembly.
• Barrel -
This is a chamber in which the reciprocating screw is
located
The barrel us heated by electric heater bands.

7. Nozzle-
The nozzle forms a sealed connection between
the barrel and the sprue bushing of the mold.
Temperature of the nozzle is set near the plastic melt
temperature.
Reciprocating screw-
The reciprocating screw compresses and melt the
plastic material and also moves the material towards
the die.There are three main zones.
-feeding zone
-transition zone
-metering zone

8. Process
• Granulated or powdered plastic is fed from a
hopper into the injection molding machine.
• The rotating screw inside barrel carries the
plastic along the barrel to the mold .
• Heaters surround the barrel melt the plastic as
it travles along the barrel.

9. • The screw is forced back as the melted
plastic collect at the end of the barrel.
• Once enough plastic has collected a
hydraulic ram pushes the screw forward
injecting the plastic through a sprue into
a mold cavity.
• The mold is warmed before injecting and
the plastic is injected quickly to prevent it
from hardening before the mold is full.

10. • Pressure is maintained for a short time to
prevent the material creeping back during
setting (hardening)
• This prevent shrinkage and hollows ,
therefore giving a better quality product.
• The molding is left to cool before
removing(ejected) from the mould .The
molding takes on the shape of the mold
cavity.

11. Advantages
• High production rate
• Can process a wide range of materials.
• Scrap material can be recycled and reused.
• Smooth surfaces can be achieved.
• Full automation is possible with injection molding.
• More uniform melting.

12. Disadvantages
•High initial equipment investment.
•High startup and running costs.
•Contamination of raw material affect the
quality of final product.
•Problems with required heating /cooling of
the plastic material.

13. Applications
• Automotive components
• Cable assemblies
• Computer electronic components
• Medical and dental products
• Toys, hobby
• Beverages
• Laboratory equipment