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  2. 2. TOPIC OF PRESENTATION Injection molding process 2
  3. 3. “Group Members” • • • • Noman Asif (2010-IM-112) Ramiz Raja (2010-IM-132) Ali Muhammad (2010-IM-149) Ali Zulfiqar (2010-IM-152) 3
  4. 4. Contents: • • • • • • • • Introduction of the industry Introduction to the process Equipment and tools used Parts manufactured Materials used Alternative materials Process on the job Summry 4
  5. 5. Industry visited: • Sharp Electric industry G.T Road Gujranwala Pakistan. • Vendor of Boss industry. • Categories: Washing Machine & parts manufacturing. 5
  6. 6. Process Studied "Injection molding” DEFINITION: Injection molding is a manufacturing process for producing parts from both thermoplastics and thermosetting plastic or other materials. For this purpose injection molding machine is used. Used for manufacturing of variety of parts from small components to entire body panel of cars. 6
  7. 7. Typical parts are fittings, containers, bottle tops, housings, and more. For glass rubber also injection molding is used. Most common plastic “finishing” process. Injection molding process is primary manufacturing process. 7
  8. 8. MOLD Mold is a hollowed out block used when components are to be made from plastics or rubber glass etc. The mold is made from metal, usually either steel or aluminium. Designing and making mold for injection molding is more complicated than making extrusion die 8
  9. 9. Mold of REHL 9
  10. 10. Mold for Chair 10
  11. 11. 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  11
  12. 12. Types of plastics: Thermoplastics Can be reused e.g. PP Thermosetting plastics Can not be reused 12
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  15. 15. VIDEO: 15
  16. 16. Steps: • 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 travels along the barrel. 16
  17. 17. • The screw is forced back as the melted plastic collects 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 mould cavity. • The mould is warmed before injecting and the plastic is injected quickly to prevent it from hardening before the mould is full. 17
  18. 18. • Pressure is maintained for a short time to prevent the material creeping back during setting (hardening). • This prevents shrinkage and hollows, therefore giving a better quality product. • The moulding is left to cool before removing (ejected) from the mould. The moulding takes on the shape of the mould cavity. 18
  19. 19. Advantages: • • • • • • • • • High production rate Can process a wide range of materials Relatively low labor Less or no finishing of parts required Scrap material can be recycled and reused Low operation cost Smooth surfaces Full automation is possible with injection molding More uniform melting 19
  20. 20. Disadvantages: • • • • High initial equipment investment High startup and running costs Difficulty in designing molds Contamination of raw material affect the quality of final product • Requires high pressures • Problems with required heating/cooling of the plastic material 20
  21. 21. Parts manufactured: • Rehl for The holy Quran • Table • Chair 21
  22. 22. Raw material used: • Polypropylene PP 22
  23. 23. RECYCLING • Used broken tables, chairs etc. are crushed in crusher. • Crushed parts are melted. • Small grains are made. 23
  24. 24. What is polypropylene?? Thermoplastic polymer used in a wide variety of application including packaging and labeling chairs, tables etc. Melting point 130-171C 266-340 F 24
  25. 25. Why polypropylene???? • • • • • • • Low cost Flexible Tough Light weight Low moisture absorption Easy to maintain and clean Can be recycled 25
  26. 26. Alternatives of PP • polystyrene (low-cost material) • ABS or acrylonitrile butadiene styrene (a co-polymer or mixture of compounds used for everything from Lego parts to electronics housings) • Nylon (chemically resistant, heat-resistant, tough and flexible - used for combs) • PVC (more common in extrusions as used for pipes, window frames, or as the insulation on wiring where it is rendered flexible by the inclusion of a high proportion of plasticizer). 26
  27. 27. FINAL PRODUCTS: 27
  28. 28. Material wasted: Less material is wasted Can be used again after melting 28
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  31. 31. Summary • Injection molding process is a manufacturing process used to manufacture parts from plastic, rubber and glasses. • First of all raw material is melted then injected in the mold and product is ready. • Polypropylene is used for table chair and rehl as raw material. • Polypropylene is cheap, has low melting point can be recycled. • In injection molding less material is wasted, and final product is of low cost. 31
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