The plastic extrusion process

How the plastic extrusion process works

The plastic extrusion process is used to make continuous lengths of shapes like tubes and pipes.

Mostly thermoplastics are processed in plastic extrusion process. Some thermosets can be extruded into weather-stripping by adding catalysts to the rubber material as it is fed into the extruder.

Step by step

Plastic extrusion process - Plastics manufacturing - DemaPlasTech

Step 1

Raw plastic materials like granules, pellets, or powder are loaded into a hopper and then fed into a long heated cylindrical chamber called an extruder. It is moved through this chamber by a revolving screw. Some extruders can have either one or two revolving screws.

Step 2

The plastic is melted both by the compacting action of the screw and the heated extruder wall. At the end of the heated chamber, the molten plastic is forced through a small opening called a die to form the shape of the finished product.

Step 3

As the plastic is extruded from the die, it is fed onto a conveyor belt for cooling. Cooling can happen by air or water. The process is similar to the injection moulding process except that the melted plastic is forced through a die instead of into a mould.

Uses for extruded plastics

Examples of extruded products include lawn edging, piping, film, coated paper, insulation on electrical wires, gutter and down pipes, plastic timber, and door and window profiles.

In fact any plastic product with a constant cross-section can be made using the plastic extrusion process.

Extruded plastics piping - Plastics manufacturing process - DemaPlasTech
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