How to Manufacture PET Bottles
PET bottles are the preferred containers for most soft drinks as well as for light household cleaners and other consumer goods. Small manufacturers can make custom PET bottles using virgin or recycled PET flakes and a simple, easy-to-obtain manufacturing apparatus. With more and more specialty consumer products manufacturers launching new products, the need for custom-designed PET bottles is increasing. Therefore, entrepreneurs in the consumer products industry are turning to small packaging manufacturers to obtain these bottles. Since the cost of entry is not great and the process is relatively simple, PET bottle manufacturing represents an exciting small business opportunity.
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Things You'll Need
- Virgin or recycled PET flakes
- PET preform molding device*
- PET preform mold
- Injection molding device*
- Custom PET bottle mold
- * A single machine which holds both molds and completes the entire process is now available instead of two separate molding devices.
Instructions
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Obtain PET from a reliable supplier. PET is manufactured by polymerizing, or reacting, the chemicals terephthalic acid and ethylene glycol so as to produce pellets of a raw material called polyethylene terephthalate, which is abbreviated to PET. However, because PET is not biodegradable, it is possible to obtain raw PET for bottle manufacturing from shredded recycled plastic bottles. Some small manufacturers use a bottle manufacturing line that actually shreds bottles to produce the necessary raw material.
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Mold the raw PET pellets or recycled shredded PET into a preform, which resembles a test tube in appearance.This is done using either a separate preform molding machine or a combined one-step apparatus that includes the preform and final molding within one machine. The preform can be made to include the bottle threads, even though it is too thick to serve as an actual bottle until it is stretch molded.
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Stretch mold the preform. The preform is placed into a mold that corresponds to the shape of the bottle and is contained within the injection molding device. In some cases the original preform tube is cut into shorter lengths before being placed in the stretch-molding device. Hot, pressurized air is blown through a steel tube that pushes the heated preform tube against the mold so that crystallization takes place as the heated preformed PET is forced to take the shape of the inside of the mold.
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Trim the bottles as necessary to remove excess PET, and then cool them with compressed air before they are either filled on-site or shipped to the location where they will be filled. Hot filling bottles is only possible when they will be used for the sale of foods of a certain degree of acidity, and this should be done only with proper equipment. In addition, pay attention to all pertinent health and safety laws when filling completed PET bottles.
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Label the bottles as necessary once they are filled. Labels are produced with separate equipment and are not usually provided by PET bottle manufacturers unless the manufacturer also fills the bottles.
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Tips & Warnings
For small businesses and newcomers to PET bottle manufacturing, a custom one-step injection device, which combines preform molding with stretch molding, is recommended. Such machines are more cost-effective for small runs and are easier to use with custom bottle molds. It is now possible to purchase a single-step molding device for PET bottle manufacturing at a reasonable price from factories in the Far East that specialize in this type of machinery. Used machinery is also available and may be the best way for new manufacturers to test the market for their custom PET containers.
Whenever possible, use recycled PET. PET creates problems when disposed of in landfills, and more and more localities are promoting PET recycling. Since PET from used bottles can be shredded and reused in place of virgin PET pellets, recycling is very efficient; it truly eliminates the dangers to the environment and disposal problems that PET bottles create.
Keep in mind, however, that some recycled PET may not meet a client's standards. This is the case when recycled PET contains shredded bottles of different colors that will not produce the color of bottle that the client needs for specific products.
References
Resources
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