The Single-Stage ISBM Process

Stretch blow moulding in the single-stage ISBM (Injection Stretch Blow Moulding) process leverages the residual heat from the injection molding phase for the subsequent blowing process, eliminating the need for separate reheating. This integrated method enhances efficiency, reduces energy consumption, and improves container clarity and strength.

Key Stages

1. Material Preparation and Melting:

• Plastic resin pellets (e.g., PET) are precisely fed into the machine’s injection unit, where they are melted and homogenized by a rotating screw under controlled temperature and pressure.

2. Preform Injection Moulding

• The molten polymer is injected under high pressure into specific molds to form the “preforms” (the test-tube-like initial shapes that include the final bottle’s neck finish). These preforms are crucial inputs in the stretch blow moulding process.

3. Preform Conditioning (Integrated):

• While still warm from the injection process, they are internally conditioned to the optimal temperature required for stretching and blowing.

4. Stretching and Blow Moulding:

• The conditioned preforms are transferred to the blow molds within the same machine.
• A stretch rod stretches the preform axially, while high-pressure compressed air is introduced to inflate it against the mold cavity, forming the final bottle shape.

5. Cooling and Ejection:

• The newly formed bottle is rapidly cooled within the mold to solidify its shape and properties. The mold then opens, and the finished bottle is automatically ejected.