Press Forming is used with thermosetting plastics.
- A 'slug' of thermosetting powder is placed into the 'female' mould.
- A former (or male mould) is pressed into and pushes the plastic into the mould.
- Very high temperatures and pressures are needed to liquefy the powder.
- The plastic is set into a permanent shape.
Vacuum forming is used with thermoplastics.
- a mould is a put on the vacuum bed.
- the bed is lifted close to the heated plastic.
- the air is sucked from under the plastic, creating a vacuum.
- this forces the plastic onto the mould.
Blow moulding is used with thermosetting and thermoplastics.
- A tube of softened plastic is inserted into the mould.
- Air is injected into the mould which expands the plastic into the shape of the mould.
This method produces hollow shapes :)
Die Casting is used with thermoplastics.
- The material is melted and poured into the die (mould). Simples :)
Some plastic resins can be cold-poured into the mould. they harden and set through a chemical reaction.
Injection moulding is used with thermosetting and thermoplastics.
It is similar to die casting but uses a closed mould and high pressure.
The moulds are made from tool steel - quite expensive.
The plastic in melted in built-in heaters.
it is an automatic and continuous process.
Extrusion moulding is used with thermoplastics.
- The material is melted and forced under pressure through a die(mould).
- There is a built-in heater.
- It produces long continuous strips of moulding the same size as the exit hole.