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What is 2-axis stretch-blow molding?

The 2-axis stretch-blow molding method uses "a Preform" that is made by the injection molding process beforehand. The Preform is stretched in both the hoop direction and the axial direction by high magnification and is molded into the desired bottle shape by high-pressure air.

The process of 2-axis stretch-blow molding progresses from preform molding to preform heating, stretching, blow molding and finally ejection.

Compared to direct blow molding, 2-axis extension blow molding has several advantages:

  1. It is possible to produce a lot of units resulting in high productivity.
  2. The mouth of the bottle is well made and the accuracy of its size is consistent.
  3. The differences among bottle weight and content capacity are slight.
  4. Since waste material from production of the Preform is minimal, there is potential to reduce production costs.

2-axis Stretch-Blow Molding Processes


Step 1. Preform molding process

Melting resin is injected into the metal mold cavity and the Preform is made.

Step 2. Blow molding process

The Preform is heated to the appropriate temperature and then simultaneously stretched with a stretch stick and placed in a blow metal mold. High-pressure air is used to expand the hot parison and press it into a mold cavity.

Step 3. Ejection process

The air pressure is maintained until the plastic cools and hardens. After which, the metal mold is opened and the bottle is ejected.

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