PLASTICS TYPES, MOULDING MACHINES

1. MANUFACTURING OF PLASTIC
COMPONENTS
UNIT - 5

2. ORGANIC MATERIALS
 Natural – Wood, Coal, Petroleum &
Natural Rubber
 Synthetic – Plastics, Synthetic rubber,
Ceramics & Glass
 Organic material - Polymers

3. Polymers
 Poly means ‘Many’ & ‘Mers’ means
‘Parts’
 Polymer built of several repeating
units(Monomer)
 Monomer – small molecules
 Polymer is made up of thousands of
monomers jointed together to form
large molecule.
 Plastics – Organic polymer

4. Polymerization process
 A Polymer is made up of linking thousands
of monomer and thus obtaining large
molecule is called Polymerization process
 Additives – Plasticizers (liquid form) –
Water, Organic solvents & resins
 Catalyst – Promote faster & complete
Polymerization
 Dyes – Impart desired colour
 Initiators – Initiate the reaction (H2O2)
Hydrogen peroxide

5. Plastics
 Can be moulded into required shape
with the help of pressure or heat or
both heat and pressure
 Resin – liquid form of plastics, also raw
material for making plastics
 Types of resin: acrylic resin,
Polyethylene resin & amino resin –
Produced by polymerization process
 Catalysts, Binders & Lubricants added
with resin to form plastics

6.  Modifiers – To improve the mechanical
properties of plastics
 Lubricants – To reduce friction during processing ,
Avoid sticking to mould walls(Oils, Soaps and
waxes)
 Solvents – Dissolve fillers or Plasticizers & Allow
the processing in fluid state(Alcohol)
 Fillers – Mica, Cloth fiber
 Elastomers – To enhance the elastic properties

7. Properties of Plastics
 Elongation
 Heat resistance
 High rigidity
 Surface hardness
 High viscosity
 Density
 Chemical resistance

8. Thermosetting Plastics
 Thermosetting - Plastics which are hardened by
heat effecting non reversible chemical change .
Molecules are formed by condensation
polymerization process.
 All the molecules have three dimensional
network and very strong binding force between
molecules
 Bakelite, Polyester resin, Epoxy resin(Araldite),
Silicones, Urea formaldehyde(Amino resin) &
Alkyds

9. Thermo Plastics
 Have separate long and large size molecule arranged
side by side
 When thermoplastics are heated it becomes very soft
and rehardens on cooling
 During heating the linear bonding links between
molecules are breakup and separated. Relinking takes
place on cooling and retains their hardness.
 Cellulose nitrate – pen bodies, Table tennis balls, Frames
 Ethyl cellulose – Jigs, Fixtures, hose nozzles
 Cellulose acetate - Radio cabinets, steering wheels,
Insulating tapes

10. Synthetic resins
 Polyethylene – Fabrics, tray, pipes, tubing chemical
containers & corrosion resistant coatings
 Polystyrene - Battery boxes, radio parts, toys
 Vinyles(PVC) – Tarpaulin, Water roofing, raincoats, tubes
 Polytetra fluroethylene (Teflon)- Gaskets, Greaseless
bearing, Electrical insulators, Chemical containers
 Polyamide(Nylon) – Gears, wire insulation, combs,
Bearings and couplings

11. S.
No
Thermoplastics Thermosetting plastics
1 Softened by heating Cannot be softened by
heating
2 Structure is made of linear
chain molecule
Structure is made of cross-
linked molecule
3 Produced by addition
polymerization process
Produced by condensation
polymerization process
4 Can be reproduced by
heating and cooling
Cannot be reproduced
5 When the temp increases
the plasticity also
increases
Plasticity is stable at high
temperature
6 Softer and less strong Harder and strong
7 Scrap can be reused Scrap can not be reused

12. INJECTION MOULDING
1) RAM OR PLUNGER TYPE INJECTION MOULDING

13. THERMOPLASTICS - INJECTION MOULDING
2) SCREW TYPE INJECTION MOULDING

14. THERMOPLASTICS – INDUSTRIAL APPLICATION
2) BLOW MOULDING

15. THERMOPLASTICS – INDUSTRIAL APPLICATION
3) ROTATIONAL MOULDING

16. THERMOPLASTICS – INDUSTRIAL APPLICATION
4) FILM BLOWING

17. THERMOPLASTICS – INDUSTRIAL APPLICATION
5) SHEET MAKING

18. THERMOPLASTICS – INDUSTRIAL APPLICATION
6) EXTRUSION PROCESS

19. THERMOPLASTICS – INDUSTRIAL APPLICATION
7) VACUUM FORMING PROCESS ( THERMO FORMING)

22. THERMOSETS
1) COMPRESSION MOULDING

23. THERMOSETS
2) TRANSFER MOULDING

24. BONDING OF THERMOPLASTICS

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