Next process, extrusion, is popularly used in the plastics industry. This is a machinery process where raw plastics are shaped into ribbon or other desire profiles.
For better understanding the whole process below is the short video:
This one explains the basics and shows the process more into details:
Plastic granules are supplied through a hooper inside the extruder machine. The granules in the screw melt into a liquid and are moved forward. The liquid is forced through a die. The die is located at the end of screw. The shape of the die influences the shape of the coming liquid plastic. The extruded shaped material is cooled and forms a solid shape.
The main parameter in extrusion is temperature
Materials used in extrusion are thermoplastic materials such as polystyrene, nylon, polypropylene and polythene. Temperature changes the state of the thermoplastic material and as we have seen the desired shape can be easily obtained.
A very important part of the extruder is the screw. Most of the screws have three zones:
Feed zone/solids conveying zone: provides the resin into the extruder.
Melting/transition/compression zone: The channel depth decreases and the biggest percentage of the material is melted due to the pressure and also the high temperature.
Metering/melt conveying zone: the last particles of thermoplastics are melted here. They are also mixed in order to get the uniform temperature and composition. This channel part keeps the same width.
The main products we can obtain are pipes, tubing, pallets, weather stripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
Simple, isn’t it?