5.4.2

Polymers: Specialist Techniques & Processes

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Line Bending, Press Moulding and 3d Printing

Many products are made from polymers. There are a number of processes used for making polymer-based products.

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Line bending

  • Line bending allows polymers to be bent into a shape.
    • Line bending is used for thin pieces of polymers.
  • The polymer is laid onto a line bender or strip heater.
    • The heat softens the area above the heated wire.
  • The polymer can be bent to the desired angle and left to cool.
    • Once cool, it will harden and stay at that angle.
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Press / compression moulding

  • Press / compression moulding involves compressing a sheet of polymer over a 3D shape.
    • The pressure from the yoke / upper mould focuses the sheet to replicate the mould below it.
  • A waste material called flashing is removed from around the edge.
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3D printing

  • 3D printing allows products drawn on CAD to be printed in a 3D form.
    • CAD stands for Computer-Aided Design.
  • The printer takes the image and slices it into layers.
    • The printer can print these layers to build up the shape of the product.
  • 3D printing helps speed up prototyping and idea generation.

Injection Moulding and Vacuum Forming

Injection moulding and vacuum forming are used for making polymer-based products.

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Injection moulding

  • Injection moulding produces complex 3D shapes.
    • For example, plastic chairs and Lego bricks.
  • Injection moulding can run continuously.
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Process of injection moulding

  • Granules are fed into a hopper where an archimedean screw rotates.
    • This moves the granules down the tube.
    • This heats the granules up.
  • The liquid is forced through a sprue gate by a hydraulic ram.
    • This pushes the liquid forward.
  • The mould is filled up with liquid plastic and left to cool.
  • The 3D product is released.
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Vacuum Forming

  • Vacuum forming produces hollow 3D objects.
    • For example, trays and masks.
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Process of vacuum forming

  • A 3D mould is placed into the machine.
  • A sheet of thermoforming polymer is clamped above the mould.
    • HIPS is the thermoforming polymer that is usually used.
  • A heater begins to soften the HIPS, making it malleable.
  • The mould is lifted up into the HIPS, forming the 3D shape.
  • The vacuum removes any air, wrapping the HIPS around the 3D mould.

Jump to other topics

1Core Technical Principles

2Paper & Board: Specialist Technical Principles

3Timber: Specialist Technical Principles

4Metal: Specialist Technical Principles

5Polymers: Specialist Technical Principles

6Textiles: Specialist Technical Principles

7Designing & Making Principles

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