The document discusses the injection molding process used at Sharp Electric industry in Gujranwala, Pakistan. It describes how plastic parts like chairs, tables, and religious items are manufactured. The process involves melting plastic raw materials like polypropylene and injecting them into molds under high pressure to form the desired shapes. The document outlines the key steps, equipment, materials used, and advantages of the injection molding process.

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2. TOPIC OF PRESENTATION
Injection molding
process
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3. “Group Members”
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Noman Asif (2010-IM-112)
Ramiz Raja (2010-IM-132)
Ali Muhammad (2010-IM-149)
Ali Zulfiqar
(2010-IM-152)
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4. Contents:
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Introduction of the industry
Introduction to the process
Equipment and tools used
Parts manufactured
Materials used
Alternative materials
Process on the job
Summry
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5. Industry visited:
• Sharp Electric industry G.T Road
Gujranwala Pakistan.
• Vendor of Boss industry.
• Categories:
Washing Machine & parts manufacturing.
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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.
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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.
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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
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9. Mold of REHL
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10. Mold for Chair
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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
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12. Types of plastics:
Thermoplastics
Can be reused e.g. PP
Thermosetting plastics
Can not be reused
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15. VIDEO:
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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.
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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.
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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.
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19. Advantages:
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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
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20. Disadvantages:
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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
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21. Parts manufactured:
• Rehl for The holy Quran
• Table
• Chair
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22. Raw material used:
• Polypropylene PP
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23. RECYCLING
• Used broken tables, chairs etc. are
crushed in crusher.
• Crushed parts are melted.
• Small grains are made.
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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
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25. Why polypropylene????
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Low cost
Flexible
Tough
Light weight
Low moisture absorption
Easy to maintain and clean
Can be recycled
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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).
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27. FINAL PRODUCTS:
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28. Material wasted:
Less material is wasted
Can be used again after melting
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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.
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