How Are Plastic Water Bottles Made?
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Two-Step Process: Step 1
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Plastic water bottles are manufactured in two ways. The first method involves a two-step process with the use of preforms or parsions which are shaped like a test tube. This is called the Injection Stretch Blow Molding (ISBM).
The first step begins with the injection of liquefied polyethylene terephthalate (PET) into a cavity where the test-tube shape is formed. This preform is then cooled down. It is then taken to the conditioning station, where it is reheated and softened in preparation for the second step.
Two-Step Process: Step 2
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The second step is the stage in which the preform takes its final shape. It involves the process of blowing where the preform is heated rapidly and placed in a stretch-blow molding Hot air is introduced into the hollow plastic which will inflate it to its finished product. The company name and the design number is found at the bottom of the bottle. This is encrypted during the blowing stage before it is ejected for cooling.
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One Step vs. Two Step
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In the second method, all processes involved in making water bottles are done in a single machine. This reduces the need for manpower, energy and space required for the machinery.
The two-step method is advantageous for water bottlers that want to stock on preforms or prefer to buy them from a supplier. If ample preforms are available, this system would prove to be faster than using the single step process. One blowing-ejection cycle can produce an average of 1300 to 1500 plastic water bottles, depending on bottle volume.
Rate of Production
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Rate of production is determined by the wall thickness of the bottle and the number of cavities in the machine. Bottles with wall thickness of 3.0mm to 3.6mm will take about 14 to 16.5 seconds to blow the preform into its full sized shape.
Recycling PET
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Recycling plants can revert used bottle to raw materials through chemical processes like hydrolysis where high water pressure on supercritical conditions is applied to the PET. Users of plastic water bottles are encouraged to recycle them because decomposition of plastic take hundreds of years.
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