Plastic bottles, whether it be a custom plastic bottle, colored bottles, or gallon plastic jugs, have revolutionized the way we use liquids. It only takes two pounds of plastic to carry about 10 gallons of a beverage, where it would take eight pounds of steel, three pounds of aluminum, and more than 40 pounds of glass to deliver that same amount! People in America alone are using two and a half million plastic bottles every hour, and the whole work is making and using 600 billion pounds of plastic in a year. Making plastic bottles is a big business, so how does a plastic bottle company do it?
Making Plastic Bottles: Choosing Materials
The first step in making plastic bottles in choosing the kind of plastic you want to use. The plastic comes in tiny pellets, and it might be recycled plastic from old bottles and other things, or it might be bits of PET, the clear plastic that is most commonly used for beverages. PET is short for polyethylene terephthalate, which is a substance that is particularly lightweight, but also strong. Whatever material is chosen, it is loaded into ovens. These special ovens heat the material to 260 degrees centigrade.
Making Plastic Bottles: Moulding
Injection molding is used throughout the United States in more than 16,000 different facilities across America. This is one of the most common ways of making plastic bottles. The plastic pellets melted in the oven are injected into small molds, and the tubes are re-heated and then put into molds shaped like bottles. Air is then forced in under high pressure, which inflates the plastic in the molds and allows the bottles to take their final shape.
Making Plastic Bottles: Cooling
Once a bottle is shaped in the mold, the nature of plastic is such that it must be instantly cooled or it will droop and lose its shape. The cooling can be done by running cold water all around the molds, or even by using liquid nitrogen. Sometimes the bottles are even cooled just by blowing air around them. At this point, some of the bottles will be taken off the line at random and inspected, to make sure the quality is right.
Making Plastic Bottles: Shipping Out
If the randomly checked bottles have passed the tests, the bottles are ready to be packed up and shipped out. The bottles are sent out to whatever business ordered them, and that business will fill them with some kind of liquid and put caps on them. These steps are almost always accomplished by machine.
Plastic is one of the most useful and versatile materials that humankind has ever invented. However, it does take many hundreds of years for plastic to naturally break down, so it’s important that we recycle plastic so we can take advantage of this useful material without polluting our environment.