Extrusion of plastic is a method of manufacturing many common products that are made in industry. The basic concept behind extrusion is that its melted forced through the extruder. It works in a way that is similar to how many kinds of pasta are made. When it exits the machine after being forced through, it has been given a specific shape depending on the product being manufactured. This shape could be almost anything from mono-filament fishing line, to water pipes, to siding for a house. The number of different products that can be made using extrusion is almost unlimited. It is pretty safe to say that the US would not be the same if it weren’t for extruded plastic. Let’s examine more closely some of the details that are involved.
The raw plastic that you start with before it is melted down is called resin. This is small particles like beads. The resin is loaded into the hopper of the extruder. In the hopper, colorants can be added to it to change the color of the end product. UV inhibitors can also be added, which will protect it from being damaged by the sun.
The screw does a lot of the work of the extruder machine. First, the screw feeds the plastic resin into the barrel of the machine. The barrel heats up gradually, until it is molten. Once its molten, the screw also serves to mix it all together with the colorant and other additives. Then the molten plastic is fed through a screen that acts like a filter. The screen catches any particles that have been mixed in like stones or pieces of metal possibly.
Once the plastic has been melted and screened, it is then forced into the die. The die gives its shape. A very common shape that is used is a wide, thin film. This can be made into sticky tape, wrap, bags, or any number of products. A film of plastic can also be further formed into other things like siding, with the use of rollers. Tubes and pipes can be extruded using a special die that allows the center of the tube to stay open. This is how things like drinking straws, tubes, hoses, and plumbing pipes are manufactured.