How Does Stretch Blow Molding Work?

stretch blow molding machine

When it comes to manufacturing, many companies rely on various services yet have little knowledge about the processes themselves. Take the stretch blow molding machine as a perfect example. Although different industries depend on it to produce finished products based on exact specifications and tolerances, they don’t fully understand how it works.

Keep in mind there are several unique types of stretch blow molding machines, including the all-electric and continuous motion L Series. However, the goal is always to produce precision plastic bottles and containers used for things like water, juice, tea, cooking oil, sauces, condiments, alcoholic beverages, and even cosmetics. For superior quality and cost-effective products, it’s essential that you work with one of the top stretch blow molding manufacturers.

The Process Using a Stretch Blow Molding Machine

As for the process itself, all stretch blow molding machines work in relatively the same way. Most often, this manufacturing method creates PET bottles used for the various products mentioned, plus more. Although experts have relied on the stretch blow molding machine for more than 30 years, the technology continues to advance. As a result, the process is ideal for both standard and customized solutions.

There are two categories for stretch blow molding machines, single-stage, and two-stage.

Single-stage
The single-stage machine has an extruder that injects a parison into a preformed mold that cools the preform rapidly to produce the desired form. After cooling down, this stretch blow molding machine reheats the preform, followed by placing it in the bottle mold. As the parison softens, it stretches to roughly twice its original length.

At that point, the machine forces compressed air into the now stretch parison, expanding it to the mold size and shape. Again, the product cools and the lid of the mold opens, revealing a plastic bottle with a hollow interior. For specialty products like wide-mouthed jars and lower production rates, stretch blow molding manufacturers typically use the single-stage machine.

Two-stage
Unlike single-stage stretch blow molding machines, those in the two-stage category work with an already made preform. Starting off with a manufactured and cooled preform, compressed air stretches out the plastic to the size and shape of the mold, after which time the machine ejects it.

Of the two options, this one is the most expensive. For that reason, stretch blow molding manufacturers use it for high production runs. Some examples of the types of products this machine makes are narrow-mouthed water bottles, liquor bottles, and wide-mouthed peanut butter jars.

Outstanding Machinery
When researching different stretch blow molding manufacturers for your project, select one that uses outstanding machinery. At Pet All Manufacturer, we provide our customers with state-of-the-art equipment that ensures precision finished products.

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