Polymers

• Polymer classifications:

  • thermoplastic
  • thermosets
  • elastomers
• Urea Formaldehyde (UF) - Thermoset

  Uses - buttons, toilet seats, electrical fittings
• Polyvinyl Chloride (PVC) - Thermoplastic

  Uses - rain, water, and sewage pipes
• Polyethylene terephthalate (PET) - Thermoplastic

  Uses - signs, drink bottles, and bank/smart cards
• Epoxy resin - Thermoset

  Uses - adhesives, sealants, coatings
• Polypropylene (PP) - Thermoplastic

  Uses - chemical containers and tanks
• Polyester resin - Thermoset

  Uses - light fittings, toys
• Advantage of CAD/CAM?

  Time and cost efficient

  Improved client accessibility

  Improved machining capabilities
• Disadvantage of CAD/CAM?

  Expensive to set up

  Needs a skilled workforce of engineers

  Downtime required for maintenance
• Vacuum forming:

  • heating a plastic sheet until soft
  • drape it over a mould
  • a vacuum is applied, sucking the sheet into the mould
  • sheet is then ejected from the mould
• Injection moulding:

  • thermoplastic polymer is heated above its melting point
  • the molten fluid is then injected into the mould
• Blow moulding:

  • inflate/blow a thermoplastic molten tube "parison" into the mould's cavity