15. Polymer processes Flashcards
What are the polymer processes?
- vacuum forming
- thermoforming
- calendering
- line bending
- lamination
- injection moulding
- blow moulding
- rotational moulding
- extrusion
- compression moulding
What is the polymer stock form used for vacuum forming?
thermoplastic sheet up to about 6mm thickness
What are the key features of vacuum forming?
- moulds relatively easy to make
- moulds need a draft angle, air holes and rounded corners
- not cost effective for one off manufacture
- small scale batch and mass production
What products are made by vacuum forming?
- lightweight trays
- box inserts and liners
- takeaway coffee cups
- yoghurt pots
Draw the process diagram for vacuum forming, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for thermoforming?
thermoplastic sheet about 6mm thickness
What are the key features of thermoforming?
- like vacuum forming, but additional mould is pressed onto the surface of the polymer sheet at the same time as the vacuum is applied
- good for fine detail such as moulding in logos
- slow process
- used in industrial production
What products are made by thermoforming?
- bath
- food packaging (fruit punnets, cake boxes, sandwich boxes)
Draw the process diagram for thermoforming, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for calendering?
thermoplastic pellets
What are the key features of calendering?
- heated rollers squash and stretch the polymer to make it thinner
- industrial production method, carried out by specialist manufacturers
- used for continuous production
What products are made by calendering?
thin polymer sheet and film
Draw the process diagram for calendering, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for line bending?
thermoplastic sheet
What are the key features of line bending?
- uses an electrically heated element that provides heat along a line
- quite slow and labour intensive
- used in school or college workshops
- suitable for one-off or limited batch production
What products are made by line bending?
acrylic boxes, shelves or point-of-sale displays
Draw the process diagram for line bending, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for lamination?
fibre based composite sheets (GRP, CFRP)
What are the key features of lamination?
- requires a former to mould around
- polyester resin used as the polymer
- top gelcoat is applied which may contain pigment
- CFRP requires an autoclave for the product to cure
What products are made by lamination?
- boat hulls
- kayaks
- train carriages
- theatre and film props
- theme park rides
Draw the process diagram for lamination, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for injection moulding?
thermoplastic granules
What are the key features of injection moulding?
- complex 3D shapes can easily be made
- fast industrial production method
- high initial tooling cost
- used for large scale mass or continuous production
What products are made by injection moulding?
electrical product casings (computers, TVs, vacuum cleaners, calculators)
Draw the process diagram for injection moulding, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for blow moulding?
thermoplastic tube ‘parison’
What are the key features of blow moulding?
- produce hollow thin walled components
- high initial tooling cost
- used for continuous production
What products are made by blow moulding?
- drinks bottles
- shampoo bottles
- detergent bottles, etc
Draw the process diagram for blow moulding, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for rotational moulding?
thermoplastic powder or granules
What are the key features of rotational moulding?
- seamless hollow components with a large wall thickness
- mould continuously rotated through heating and cooling
- large scale batch or mass production
What products are made by rotational moulding?
- traffic cones
- kayaks
- water tanks
- kerosene tanks
- children’s play equipment
Draw the process diagram for rotational moulding, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for extrusion?
thermoplastic granules
What are the key features of extrusion?
- like injection moulding, except polymer is forced through a die
- industrial production method
- continuous production
What products are made by extrusion?
- solid rods
- tubing
- angle sections
- curtain track
Draw the process diagram for extrusion, with labels.
See in person flashcards with pics on.
What is the polymer stock form used for compression moulding?
thermoset polymer charge ‘slug’
What are the key features of compression moulding?
- uses a pre-weighed ‘slug’ of polymer
- polymer removed from moulds while still warm
- large scale batch production
What products are made by compression moulding?
- electrical light fittings
- switches
- plugs
- picnic plates and cups
