Plastic Industries

Synthetic plastics: These come from crude oil, natural gas or coal.
 

Bio – based plastics: These are derived from renewable products such as starch, carbohydrates, bacteria, vegetable fats and other organic materials.
Factories make plastic straws, cutlery, cups etc. via injecting plastic into moulds. The process starts with loading polystyrene pellets into a machine called an “extruder”. Pigments are added for coloured plastic. The extruder uses gas to heat the pallets until they melt.
 

For cups: The molten plastic is forced through a machine called “die” to shape a hard plastic sheet. The sheet then passes via a gas fired oven which heats the hard plastic until it is malleable. It then enters a thermal forming machine which vacuums the sheet into the mould cavities from row after row of cups. The cups are then cut of the sheet (the left over plastic is re – melted) and passed on to a conveyer belt which transports them to a machine called the “lip roller”. This machine uses gas to re – heat the cups just enough to make the plastic flexible so the rim can be folded.
 

For cutlery:  Polystyrene and polypropylene pellets are melted and the molten plastic is added to the moulds. A built in cooling system solidifies the plastic in about 10 – 15 seconds.
 

For Straws:  A different kind of gas fired extruder melts the pellets and forces the molten plastic through a circle shaped die. As the long continuous straw exists the extruder, it cools and hardens in a tank of chilled water. As it leaves the tank the knife chops it into individual straws