How are PET plastic bottles made?


There are many methods used to make PET plastic bottles […]

There are many methods used to make PET plastic bottles, but the most common method can be broken down into the following steps:

Step 1: First heat the PET to melt it into a molten state, and then put it into a tubular mold. This process is called injection molding. Once the PET becomes the same shape as the mold, it is called a parison. After the system has cooled, the parison is cut to the correct length.

Step 2: The parison is then reheated and placed in a mold shaped like the bottle being manufactured. Then, a steel rod is placed inside the parison itself, and high-pressure air is blown to stretch the parison into the shape of the mold surrounding it. The molecules inside the PET are then polarized, and the stretching process leaves you with a plastic bottle.

Step 3: Then the bottle must be quickly cooled and removed from the mold. Manufacturers often use several different methods to quickly cool bottles. Some of these methods are direct, others are indirect. For example, water can be pumped through pipes surrounding the mold to indirectly cool plastic bottles. Alternatively, the plastic can be cooled by directly applying carbon dioxide.

Step 4: Then reduce most of the bottles produced by the manufacturer to a certain size. If the bottle is made in a continuous molding process, you need to trim a bottle from the bottle next to it. If the bottle is made in a discontinuous molding process, some excess plastic may infiltrate. This will require pruning.

Step 5: Now the bottle can be delivered to the destination.

What is the role of the compressor when making PET plastic bottles?

No matter which method the manufacturer uses to produce PET plastic bottles, compressors, there is a common problem. Many different types of compressors are used throughout the industry, and compressors are the hardware that needs the most attention.

The compressor is responsible for injecting high-pressure air into the parison to stretch the parison until it fits perfectly in the bottle-shaped mold surrounding it. This means that the compressor must be good enough to accurately control the overall air flow into the parison, otherwise it will not form a shape.

Traditionally, reciprocating compressors are used in the manufacturing process of PET plastic bottles. These compressors use pistons to generate a lot of pressure, but in terms of cost efficiency, they are not very good. Therefore, most new companies prefer to use centrifugal compressors. These compressors are cost-effective and use less pressure.

Is there a quality test?
During the manufacturing process of PET plastic bottles, quality tests must be carried out regularly. These tests are steps to ensure the safe use of the bottle, while also checking such things as impact resistance and permeability to carbon dioxide.

Remember that PET has a high recycling rate and sustainability is demonstrated in the manufacturing process. Now, many PET plastic bottles are manufactured using bottles that were previously recycled.