Plastic processes

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Steps of processes

1. Plastic granules are placed in the hopper. The granule mixture falls through the hopper onto the Archimedean screw.

2. The screw is rotated via the motor and gearbox. This ation forces the polymer forwards towards the heaters, where it becomes softened to the point where it is ready to be injected into the mould.

3. The hydraulic ram forces the softened polymer through the feed hole into the mould. Pressure from the ram ensures the mould cavity has been filled.

4. When sufficient time has passed to allow the polymer to cool and solidify, the mould halves are opened. as they open, ejector pins are activated to release the product from the mould

5. Once emptied, the mould is then closed ready to begin another cycle

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Advantages and disadvantages


  • Very complex 3-D shapes can be produced
  • High voloumes can be produced with consistent quality
  • Metal inserts can be included in the item being produced


  • initial set-up costs are high
  • Moulds are expensive
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Steps of processes

1. A tube of heated and softened polymer is extruded vertically downwards. This tube is called a Parison

2. The mould halves close, trapping the upper end of the Parison, effectively sealing it.

3. Hot air is then blown in to the Parison forcing it out to follow the shape of the mould

4. The mould effectively cools the polymer allowing it to be released from the mould

5. The mould halves are opened and the product is extracted

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Advantages and disadvantages


  • Once set up, blow moulding is a rapid method of producing hollow objects with narrow necks
  • Non-circular shapes can be produced


  • Moulds can be expensive
  • It's diffucult to produce re-entrant shapes i.e. shapes that do not allow easy extraction from the mould
  • Triangular-shaped bottles are difficult to produce
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Steps of processes

1. Once the moulds have been loaded with a precise weight of the thermoplastic powder the mould halves are clamped together

2. The moulds are then rotated about the arm spindle and the whole arm is rotated towards a heated to its melting point. The continously rotating mould ensures that the thermoplastic covers all of the mould.

3. The next stage of the process is the cooling chamber where the material is cooled ready to be extracted from the mould

4. the mould is then returened to the starting point where the mould halves can be seperated and the product removed

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Advantages and disadvantages


  • One-piece mouldings can be produced
  • It is ideal for both rigid, tough shapes and flexible shapes
  • A large range of sizes is possible
  • Surface textures can be applied to the finished products from textures applied in the mould.
  • Moulds tend to be cheaper than those for injection or blow moulding, since high pressures are not required
  • Cheaper moulds allow lower prduction runs


  • Only hollow shapes can be produced in this way. More complex 3-D shapes would either be blow moulded or injection moulded
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Sheet material is heated to just above its softening point and then held securely in a frame between the two mould halves.

The mould halves close and at the same time a vaccum is applie through the lower mould.

The upper mould ensures the required amount of detail is acheived.

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Advantages and disadvantages


  • It's a low-cost process
  • It' s good for smooth shapes with additional detail


  • Deep moulds result in a thinning of the wall thickness where it has been stretched
  • Its limited to simple designs
  • Trimming is usually needed
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Steps of processes

1. Thermoplastic powder is placed in the hopper; this powder then falls onto the rotating Archimediean screw, which in turn pushes the material towards a heated section of the extruder

2. The heaters soften the plastic, which is then forced through the die by the rotating screw

3. On exiting the die, the plastic product is then cooled using a water jet.

4. Further along the transfer table, the product is cut to the required length

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Advantages and disadvantages

  • Extrusion has the advantage of generally being a low-cost process that requires only simple dies.
  • Its main disadvantage is that it can only produce continous cross-sectional shapes
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Steps of processes

1. The rollers are heated to just above the softening point of the thermoplastic

2. During the rolling process, the plastic 'dough' is forced through the gap roller. These rollers determine the thickness of the material

3. The final roller is the 'chill' roller that cools the material

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Steps of processes

1. A performed 'slug' (compressed powder) of material is placed between the two halves of the mould

2. The mould is heated to a temperature that will allow the cross-links to form withing the material

3. The mould is closed onto the preform and the pressure used will force out any excess material. The moulds are held closed under pressure at the required temperature for a period of time that is sufficient to allow all of the material to be 'cured' i.e. all cross-links formed

4. When the mould is opened the product can be ejected while it is still hot and the process can begin again

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Advantages and disadvantages


  • Moderately complex parts can be produced over long production runs.
  • Although there is some heavy machinery involved, start-up costs are relatively low; moulds are less expensive than those in injection moulding
  • There is little watse material


  • It is necessary to amnufacture a preform
  • The process is restricted to products with low complexity
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it's nice but you don't have any headers as to what exactly these are the advantages and disadvantages to. for example, we don't know if you're talking about injection molding or something else.

shame really, I thought this was going to be really good..

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