
The full form of ISBM is "Injection Stretch Blow Molding."
The procedure of ISBM is used to create polymer-based primarily hollow and rotationally symmetric objects. A preform is initially created using an injection molding procedure in this tiered process. The following stage involves heating this prototype and stretching it in all directions to give it its final shape.
The thermoplastic has a relatively low flexibility since the blow molding method only gently heats the material. In any case, the inorganic makeup of effect pigments prevents them from being elastic. Between the stretched polymer and the non-stretchable effect pigments, stretching creates the void.
The more pronounced the spaces are, the greater the pigments and the higher the stretching ratio. It is possible to utilize effect pigments at stretching ratios up to 3:1. In addition, because the plastic is still semi-viscous, 1-level or 1.5-level procedures are better.
In order to create the "frost effect" in PET bottles, this void effect is employed. The surface appears to have just emerged from the refrigerator, thanks to the frost effect.
The two primary methods for injection stretch blow molding are –
Single Stage Process
Preform production and bottle blowing are carried out in the same machine in the one-stage process. The costlier 3-station process avoids the reheat stage and utilises latent heat in the preform, saving on energy costs and using 25% less tooling than the traditional 4-station technique of injection, reheat, stretch blow, and ejection.
Two-Stage Process
The plastic is initially formed into a "preform" using the injection molding technique in the two-stage injection stretch blow molding procedure. These preforms are made using the bottlenecks, which have threads on one end.
These preforms are bundled before being put into a reheat stretch blow molding machine after cooling. In the ISBM process, the preforms are generally heated with infrared heaters above their glass transition temperature before being blown into metal blow mould bottles with high-pressure air. The method always includes stretching the preform using a core rod.
Advantages:
Disadvantages:
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