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Stretch Blow Molding Defined

Perfect shaping of light weight bottles. No partling lines, no distortion. 

What is stretch blow molding and should you make your own bottles?

Stretch blow molding is the process of creating bottles (usually PET) that will be used for packaging various products, such as juices, dairy, water, etc. There are two main types of stretch blow molding: single-stage and two-stage. The following information will deal with two-stage stretch blow molding.

One of the main advantages of two-stage stretch blow molding is the process stretches the container in two directions. This biaxial stretching has several advantages. It increases the barrier properties, tolerance for drop impact, clarity, tensile strength and top load of the container. This increase in strength also allows for the reduction in material used while maintaining overall container strength. The result is a savings of 10% – 15% in material which translates into saving money.

The final bottle shape results from the combined actions of the longitudinal and circumferential stretches within the mold.


Why Are PET Bottles So Popular?

Light weight, durable, distinctive
Pet plastic containers are a popular choice for fillers due to the numerous benefits they provide both to manufacturers and consumers, in terms of design, costs reduction and convenience.

  • Lightweight: PET is lightweight reducing fuel requirements and greenhouse gas emissions during transportation.
  • Cost effective: reduction in the price point of PET versus other material such as high density polyethylene.
  • Convenient: because they are safe, lightweight, squeezable, they are also convenient for on-the-go consumptions.
  • Re-sealable: suitable for multi-serve packs.
  • Sustainable: increasing numbers of PET plastic bottles are made from recycled PET.
  • Distinctive: can be molded into different shapes, colors, or clear packaging to display the product enabling brands to use them to build identity.
  • Flexible: manufacturers can switch from one bottle shape or size to another, meaning a high level of efficiency and freedom of material choice.
  • Design flexibility: Suitable for containers of all shapes, sizes, neck finish, design and color
  • Crystal clear: Products look good, Sparkling PET bottles attract attention. Brilliant glass-clear presentation of your products.
  • Good barrier: The low permeability of PET to oxygen, carbon dioxide and water means that it protects and maintain the integrity of products gibing a good shelf life.
  • Recyclable: Most widely recycled plastic in the world with widespread collection and separation for further processing and end use.
  • Shatterproof: Compared to glass, the unbreakable nature of PET is unbreakable helping to make home a safer place.

Container Range

  • Large range of volume available
  • Liquid chilled products
  • Any shape of bottle
  • Preferential heating
  • Bottle with handle
  • Any color (transparent, white,blue, red, etc…)

Target Uses

  • Milk 
  • Fruit
  • Personal Care
  • Sauce
  • Vegetable Oils
  • Water

Making the Right Choice

Choosing the right equipment for your packaging needs can be a daunting task. There are many factors that need to be considered when selecting the optimal solution. Serac has been designing and building filling and capping equipment for over 45 years and we have the experience and the know how to design and build a machine specifically for your needs.

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