Fabrication of Plastics in polymer technology for B.Tech students in India specially for JNTU K,H&A in Andhra Pradesh Telangana and also for other Indian Universities. By Gurram.Achyuth Kumar A

1. Fabrication of Plastics
BY COMPRESSION,INJECTION,BLOWN FILM & EXTRUSION MOULDING

2. What is Fabrication?
Giving desired Shape to
Plastics is called Fabrication of
plastics.

3. Methods used for Fabrication
 Fabrication is depends upon types of plastics or Resin used.
 i.e Whether thermosetting or thermo plastics.
 Methods of Fabrication:
 1.Compression Moulding
 2.Injection Moulding
 3. Blown Film
 4. Extrusion Moulding
 5.Transfer Moulding
 6.Co Extrusion

4. 1.Compression Moulding
 Compression moulding method is used in fabrication of both thermo plastics and
thermosetting resins.
 In this process, initially, a synthetic plastic material with added fillers and ingredients is placed
between the mould and heated(130-180oC) under pressure(100-500Kg/cm2.
 The plastic material is converted in to fluidized plastic in the mould and gets moulded in to the
required shape after curing.
 Curing is done by cooling in thermoplastics where as heating in thermosetting plastics.
 Hence the required moulded article is taken from the opening of the moulded parts.

6. Compression Moulding
 Advantages:
 The initial Setup cost is low
 It gives good surface finish
 The material loss is less
 Low mould maintenance
 Product has low residual stress.
 Applications:
 It is used in fabrication of electrical parts like switches, switch boards etc.
 It is used in fabrication of buttons, gram phone records, cooker handles etc.
 Rubber products like springs, anti vibration mounting pads.

7. Injection Moulding
 Injection moulding is used in the manufacture of thermoplastics. The setup for
injection moulding of plastics is

8. Injection Moulding
Working of Injection Moulding:
 In this process, the powdered plastic is heated under 90-260o temperature in the presence of
oil or electricity.
 The hot 🔥 softened plastic from hot cylinder is then injected in to a tightly locked mould at a
controlled rate with the help of Screw arrangement or a piston plunger.
 Screw is turned by gear driven by an electric motor.
 The Mould is Kept Cool in order to allow the hot plastic to be cured and become rigid.
 The Sufficiently cured moulded material collected from extraction pins without any
deformation by opening upper part of the mould.

9. Injection Moulding
 Advantages:
 1. The speed of production is high.
 2.The cost of moulding and finishing is less.
 3 The wastage or loss of material 1s very less.
 4.Making complex shapes in single operation.
 Limitations:
 Since, a large number of cavities cannot be filled simultaneously, the design of the articles to be
moulded get affected.
 High Capital cost of injection moulding machine.
 Applications
 1.It is used in fabrication of mugs, bottle caps etc.
 2.It is also used in chairs, buckets, dust bins etc.
 3.Safety Helmets, Ice block trays, mobile phone cases, computer parts, TV Cabinets.

11. Extrusion Moulding
 Extrusion moulding is used to mould thermo plastic
materials continuously in order to make articles of uniform
cross section.
 In this process, the powdered plastic is passed through a
heated chamber to produce hot softened plastic.
 This softened plastic forced into a die by screw conveyor.
 The finished product from the die is cooled by spraying
water or exposing to air.
 Applications:
 This method is used in manufacturing of tubes, electric
cables, optical fibres, pipes etc.

12. Extrusion Moulding

13. Blown Film Moulding

14. Blown Film Moulding
 This method is used in the design of hollow shaped plastic items.
 In this process, the liquid state plastic is injected into blown film machine and
then air is blown through it.
 As a result , vertical shaped bubble will be formed and gets solidified by
cooling and then it is guided and flattened by the guide and pinched rollers
respectively.
 The resulted flattened balloon is called as lay-flat tube
 Applications:
 This method is used in manufacture of plastic bags or plastic sheets etc.